# Welcome to FTC WIKI We hope you enjoy your stay.... **This Wiki’s Purpose** This initiative is designed for current or aspiring *FIRST* Tech Challenge mechanical members. This guide will outline the beginner and intermediate aspects of *FIRST* Tech Challenge mechanics. This encyclopedia has been designed for individuals with some experience in building and assembling things, but who are stuck between skill levels where resources are either too basic or just a little above their heads. Hopefully, by the end of this guide, you will have a deeper understanding of the mechanical aspects of robotics.
**About us** We are FTC Alumni from Scotch Plains, New Jersey, veteran members of Team 17670 for 4 years, and Team Captains. We’ve both been building for 4 years and are active members in the online FTC community. We have experience with multiple build systems, including Tetrix and Gobilda, and have created many iterations of Swerve drive. # Get Started We highly recommend starting here so you have a good idea of what website features to look out for! If a [phrase or word is underlined](#user-content-fn-1)[^1], you can hover your cursor over it to learn more about it. The purpose of the annotations is to help with understanding technical phrases to novice members, without disturbing the flow of each article. internal references will bring you to another page on FTCWIKI while external references will open a different website, which we find helpful and relevant, in another tab. ### Featured Documentation


Manufacturing and Assembly	/spaces/GYXJbpT6JALoSE3QEojT/pages/pW8CgE1IVYW2nrRxOl6S	/files/J4vDkHiO3ArRrC3MNKP4
Design Style	/spaces/oV5kYQdtEQXrvJysnhMt	/files/uTyemudAWjNqLDHnkbvv
Transmitting Power	/spaces/D2GXZ5NUEk64Zn6lJiL2	/files/JboctGsoBagynMN9AcNb
Mechanism Design	/spaces/AeKUxXLHBM2YwMTaNP9G	/files/HzlCeZ4zJMNKb4dUHUvA
Intro to CAD	/spaces/43zldy7bQi3nWvvIl7LZ	/files/5e48Fa6xejmMy2OP5Q0p

[^1]: Feel free to hover over any technical terms to learn more about them # How to Compete To create a competitive robot, we will need to cover both the fundamentals and advanced techniques in FTC robot design. While examples are given in Onshape, the content can be used in any CAD software, including Fusion360 and Solidworks. # Strategic Design ### Strategic Design Strategic Design in the most fundamental starting point to building a performing chassis. It can boost any team's performance . Strategic design in summary is the factors that go into what robot your team decides to build, creating a successful build season schedule for getting it done, and executing it well for competitions. It's about priorities and tradeoffs. It's about designing a robot and playing the game within your capabilities. Without a proper strategy and team structure, you cannot succeed. Once you’ve grasped the fundamentals of [robot architecture](https://www.ftcwiki.org/design-style/), the next step to building a truly competitive FTC robot is refining your design process and engineering workflow. Top-performing teams go beyond basic functionality—they emphasize efficiency, precision, and adaptability from the earliest planning stages.

FTC 18438 Wolfpack Machina Powerplay game strategy

Understanding and outlining your game strategy is key to developing a productive design process. Starting from as simple as a whiteboard and marker, highlighting your goals and organizing what aspects of your robot archetype to focus your efforts on.

Parallel Plate Mecanum example with servo linkage PTO

# Design Workflow ### Design Workflow One of the most important habits to develop is a CAD-first workflow. Rather than cutting parts and experimenting physically, strong teams model their entire robot in CAD before building anything. This includes not just major systems like drivetrains and lifts, but also fine details like screw clearances, cable routing, and range-of-motion constraints. Designing in CAD allows you to check for part collisions, run mechanical simulations, and iterate quickly without wasting time or materials. Platforms like Onshape are especially popular due to their collaboration features, and built-in hardware libraries.

Prototyping is still essential, but it should be fast and intentional. The goal of prototyping isn’t just to build something that works—it’s to answer specific design questions. Effective teams use cardboard, foam board, or scrap polycarbonate to test geometry and mechanism concepts before committing to a final version. Each prototype should focus on validating a single factor, such as roller spacing, gear ratios, or sensor placement. Teams that document their results thoroughly, using photos, videos, and notes, are better equipped to justify decisions in their engineering portfolio and iterate with purpose. # Design Philosophy ### Design Philosophy Modular design philosophy also plays a key role in competitive success. Instead of hard-mounting everything to a central chassis, design your robot in layers or sections—drivetrain, intake, lift, and outtake—that can be independently removed or replaced. This approach simplifies troubleshooting and makes it easier to iterate between competitions. Standardizing mounting hole patterns and using quick electrical disconnects (like Anderson Powerpoles or JST connectors) can dramatically reduce pit repair time and improve robot reliability. Strategy should always guide design. The most successful teams don’t just build the “coolest” robot—they build the robot that best executes their chosen scoring path. That might mean prioritizing cycle speed and reliability over complexity or designing for field control tactics like freight hoarding, zone blocking, or rapid parking. A robot that runs a consistent four-cycle pattern every match will often outperform a robot that *can* do seven cycles but frequently fails. Finally, serviceability is critical. Your robot should be designed for easy maintenance between matches. Color-coded wiring, clean cable management, and accessible fasteners make a huge difference when time is short in the pit. Use thread locker or nylon lock nuts on high-vibration areas like drivetrains or intakes to reduce the chance of loosening bolts. Design with the assumption that something *will* break, and ask yourself: how quickly can we fix it? By combining these advanced design strategies with the core mechanical principles outlined above, your team can build not just a functional robot—but a consistently competitive one. # Custom Mechanisms Pushing the Boundaries of Robotics

*FTC 7244 Out of the Box Robotics 8 Wheel Drive Parallel Plate Gearbox*

As you experience FTC and finish a successful kitbot[^1], you will naturally want to experiment and create more unique, interesting, and complicated mechanisms to complete game tasks more efficiently, or reliably. This is a great decision! Custom Mechanisms have shown huge upside potential for teams all over the world, but creating practical systems is no simple task.

New mechanism ideologies are being tested everyday from teams all over the world who have the resources, mentorship, and backbone to support advanced development. A popular example of this is Swerve Drive, which is a drivetrain archetype which has become the norm in FRC. Teams in FTC try to literally reinvent the wheel in the name of uniqueness and ambition. If your goal is to create competitive robots which can perform at the State/National and World Championship level, the key to developing custom mechanisms is to balance tried and tested methods along with innovative solutions to game challenges. You can explore each section of this website to learn more about each aspect of FTC Mechanics in order to take your bot from a good starting point to a masterpiece of engineering. [^1]: A robot build out of assemblies designed by companies for rookie design teams to get started in competition. If it comes with an instruction booklet, It's a Kitbot # Introduction to Manufacturing and Assembly **What is Manufacturing and Assembly?** F**rom Concept to Competition-Ready** Welcome to the **Manufacturing and Assembly** section. This resource is designed to guide FTC teams through the [machining](/manufacturing-and-assembly/machining/tolerances) and [assembling](/manufacturing-and-assembly/assembly-order) their [custom robots](/how-to-build-competitive-robots/custom-mechanisms). Whether you're new to robotics and looking to integrate small custom end effectors, or a more experienced ambitious team looking to build their first custom chassis, this section offers valuable insights into the machining, [materials](/manufacturing-and-assembly/materials/material-choice), and assembly essential for robust reliable robot construction.

FTC 19099 H-Tech Into the Deep Chassis CAD

H-Tech fully built robot running in Romanian Competition

*** #### Key Topics Covered * **Ideal Manufacturing Techniques** * Overview of the best methods of making custom parts used in FTC * Which methods to apply to which parts * **Tools and Equipment** * Overview of common tools used in FTC robot construction * helpful tips to ensure assembly efficiency * **Materials Selection** * Comparison of materials like aluminum, steel, and plastics, as well as 3d printable filaments * Criteria for choosing materials based on robot requirements * Sources for procuring quality materials * **Fastening and Joining Techniques** * Methods for securely connecting robot components * Use of screws, nuts, bolts, and alternative fastening methods * Tips for ensuring structural integrity during matches * **Assembly Best Practices** * Assembly order Ideology * Alignment and calibration techniques * Strategies for modular design to facilitate easy repairs *** #### Explore the Subsections * Tools and Equipment * Materials Selection * Fastening and Joining Techniques * Assembly Best Practices * Quality Assurance *** #### Featured Tutorials * * * *** #### Manufacturing Testimonials > ""\ > — Team > ""\ > — Team # Assembly Order The way you assemble your robot can make or break both the quality of your build and how long it takes to troubleshoot and iterate. A well-thought-out assembly sequence ensures that subsystems are easy to service, mechanisms align as expected, and you're not forced to disassemble the entire robot just to tighten one bolt. Taking the time to plan and build in the right order will save your team many hours down the line.

{% stepper %} {% step %} ### Frame The first major step in assembly should always be the drivetrain and base frame. This is the structural backbone of the robot, so it must be perfectly square, stable, and dimensionally accurate. Tolerances matter—leave a small amount of play (typically 0.2–0.5 mm for bolt-clearance holes) to allow for easy part insertion, especially with laser-cut metal or CNC parts. Tight tolerances may look clean in CAD, but they often lead to binding or difficulty in assembling real-world parts. {% endstep %} {% step %} ### Drivetrain Once your base is solid, the next step should be mounting major motion components like motors, gearboxes, and drive assemblies. These parts are often hard to reach once upper mechanisms are installed. Get your wheels spinning freely, your axles supported with proper bearing mounts, and ensure there’s no misalignment before continuing. {% endstep %} {% step %} ### Scoring Systems From here, build upwards by attaching key mechanisms in a bottom-up, inside-out fashion. For example, install inner lifts or center pivots before outer intakes or side-mounted arms. Doing this makes everything accessible and reduces the chance you’ll need to undo progress to add a screw. If your robot has vertical stacking—like an arm above an intake, or a turret above a lift—always mount the lower or inner mechanism first. This order also allows you to independently test mechanisms during assembly and fix any issues while they’re still easy to reach. {% endstep %} {% endstepper %} It’s also wise to design and assemble your robot with **modularity** in mind. Subsystems like arms, intakes, or depositors should be detachable with only a few screws or nuts, allowing for quick swaps or repairs between matches. If every part is bolted directly to the chassis with no separation, your team will struggle to maintain the robot under pressure. Use standoffs, slots, and clean mounting planes so that each mechanism is its own self-contained unit. {% hint style="danger" %} ADD THESEUS MODULAR PARTS HERE {% endhint %} During assembly, take care to avoid stacking tolerances across multiple parts. Even a 0.5 mm mismatch per plate can lead to severe alignment issues when stacked across five components. Add shims or slots when needed to absorb this error, and always test-fit as you go. A part that looks right in CAD may not account for laser kerf, 3D print warping, or material inconsistencies.

Finally, keep an eye on serviceability. If you can’t reach a screw without a 6-inch hex driver or disassembling a gearbox, your assembly order—or your design—needs revisiting. The best builds make sense not only in competition but also in the pits, when you need to repair or replace parts quickly. Always assemble as if you’ll need to disassemble. By building from the base up, mounting mechanisms in an order that prioritizes accessibility, and thinking modularly, your FTC robot will not only come together more smoothly but stay reliable throughout the season. # Additive vs Subtractive Manufacturing Additive vs. Subtractive Manufacturing Custom parts can be as simple as a battery mount to something as large as a parallel plate chassis. The key to designing successful functioning mechanisms is to balance custom and off the shelf parts. Custom Parts can be made in many different ways. You should always design parts while keeping in mind how you will manufacture them. There are 2 different types of manufacturing techniques. Additive and Subtractive Manufacturing.\
{% tabs %} {% tab title="Additive Manufacturing" %} Additive Manufacturing involves adding successive layers of material to create an object. *** Additive Manufacturing works by either * melting or fusing powders * curing liquid polymer materials * melting spools of composite materials These methods are used to form final parts based off of technical sketches. Some services online even take CAD files and post process them in-house to manufacture your design. *** The surface finish is not as smooth as subtractive manufacturing, and the tolerances aren’t as precise. These processes are ideal for lighter parts, material efficiencies, rapid prototyping, and small to medium-batch manufacturing. Complex geometries, including the printing of articulating joints with additive manufacturing, are available. The geometries are more complicated, and set-up is quick and easy, with no operator required during the printing process. The most common materials used in additive manufacturing are plastics and metals. The equipment cost is less than subtractive manufacturing, and various material colors are available for most 3D printing operations. {% endtab %} {% tab title="Subtractive Manufacturing" %} Subtractive manufacturing removes material to create an object. *** Subtractive manufacturing works by material removal by * Milling * Drilling * Grinding * Cutting * Boring The material is typically metals or plastics, and the end product has a smooth finish with tight dimensional tolerances. A wide variety of materials are available. *** Change-overs are longer, but automatic tool changers help reduce time-consuming delays. The processes can be fully automated, although an attendant may oversee two or more machines.
The equipment costs are higher and usually require additional jigs, fixtures, and tooling. It is best suited for large production with reasonably fast manufacturing time but lengthy changeovers. Material handling equipment helps both processes with material loading and removal. Geometries are not as complex as additive manufacturing processes. {% endtab %} {% endtabs %} # Material Choice ### Aluminum Aluminum is lightweight and corrosion-resistant. It is easy to machine, stamp, weld, and drill, making it a popular choice for a wide range of applications, from parallel plates to electronics. It is very popular with FTC teams since it has one of highest strength to weight ratios for the price range. [See Aluminum Alloys >](/manufacturing-and-assembly/materials/aluminum-alloys) ### Steel Laser cut steel is a popular choice since it's the most cost effective metal for laser cutting. It's significantly denser than aluminum which makes it less popular for whole chassis, but it's still usable for a strong end effector part. [See Steel Alloys >](/manufacturing-and-assembly/materials/steel-alloys) ### Stainless Steel Stainless steel is a popular choice for a wide range of applications, its food safe, corrosion resistant, and easy to clean. Learn more about stainless steel and what sizes we can cut and form. ### Titanium Titanium is a high-performance metal known for its incredible strength-to-weight ratio and corrosion resistance. It’s stronger than aluminum and lighter than steel, though far more expensive. It’s best used in applications where strength and durability are critical, and weight is a constraint.\ [See Titanium Alloys >](/manufacturing-and-assembly/materials/titanium) ### Carbon Fiber Carbon fiber is a composite material that combines extremely high tensile strength with ultra-lightweight construction. While expensive and brittle under certain conditions, its strength-to-weight ratio is unmatched. Best suited for structural components where minimal weight is essential.\ [*See Carbon Fiber Options >*](/manufacturing-and-assembly/materials/carbon-fiber) ### 3D Printing Filaments Filaments offer unique flexibility for rapid prototyping and functional parts. From standard PLA and PETG to advanced materials like TPU or carbon-reinforced nylon, the right filament can provide strength, elasticity, or heat resistance depending on your design.\ [*See Filament Types >*](/design-style/optimizing-design-for-3d-printing/filaments) # Aluminum Alloys {% tabs %} {% tab title="5052" %} [Stock Sheet Supplier](https://www.midweststeelsupply.com/store/5052aluminumsheet) 5052 aluminum is a popular choice for FTC teams fabricating custom metal parts, especially with laser cutting. What sets 5052 apart from other aluminum alloys—like 6061—is its superior corrosion resistance and excellent bendability without cracking. While 6061 may be stronger in some applications, 5052 is easier to form and better suited for parts that require tight bends, curves, or precision tabs and slots. Its high fatigue strength and moderate-to-high strength make it ideal for structural brackets, chassis panels, and load-bearing supports. Additionally, 5052 performs exceptionally well in environments where moisture or oxidation may be a concern—an advantage over more brittle or corrosion-prone alloys. For teams looking for a balance of strength, formability, and durability, 5052 is one of the most versatile and cost-effective choices available. ### Physical Properties of 5052 Alloys

Characteristics	5052-O	5052-H32	5052-H34
Density	0.098 lb/in3	0.098 lb/in3	0.098 lb/in3
Ultimate Tensile Strength	28 ksi	33 ksi	38 ksi
Yield Tensile Strength	13 ksi	28 ksi	31 ksi
Fatigue Strength	16 ksi	17 ksi	18 ksi
Shear Strength	18 ksi	20 ksi	21 ksi

{% endtab %} {% tab title="6061" %} [Stock Sheet Supplier](https://www.midweststeelsupply.com/store/6061aluminumsheet) 6061 aluminum is one of the most widely used aluminum alloys in the world—and for good reason. It offers an excellent balance of strength, corrosion resistance, and machinability, making it ideal for structural components in FTC robots. Unlike 5052, 6061 can be heat-treated through a process called precipitation hardening, which significantly increases its strength while preserving its other valuable properties. In FTC applications, laser-cut 6061 aluminum excels in load-bearing structures such as drivetrains, arms, and lift systems. It handles high-impact forces well and has strong fatigue resistance, making it a smart choice for parts exposed to vibration or repeated stress. Another advantage of 6061 is its excellent weldability and compatibility with post-processing methods like anodizing, which adds a protective layer to the metal surface. While it’s less formable than 5052, 6061’s superior rigidity and versatility make it the go-to alloy for custom frames, brackets, and mounting plates. If your team needs durable, high-performance parts that can withstand competition wear and tear, 6061 is a top-tier material to consider. ### Physical Properties of 6062

	-O	-T4	-T6	-T651	-T6511
Density	0.1 lb/in3	0.1 lb/in3	0.1 lb/in3	0.1 lb/in3	0.1 lb/in3
Ultimate Tensile Strength	18 ksi	35 ksi	45 ksi	46 ksi	42 ksi
Yield Tensile Strength	8 ksi	21 ksi	40 ksi	39 ksi	40 ksi
Fatigue Strength	9 ksi	14 ksi	14 ksi	14 ksi	15 ksi
Shear Strength	12 ksi	24 ksi	30 ksi	30 ksi	25 ksi

{% endtab %} {% tab title="7075" %} [Stock Sheet Supplier](https://www.midweststeelsupply.com/store/7075aluminumplate) 7075 aluminum is one of the strongest aluminum alloys available and is often referred to as “aircraft grade.” Its high strength comes from its zinc and copper content, which give it mechanical properties comparable to, or even exceeding, some mild steels—especially in the T6 temper. 7075 is ideal for FTC teams building components that must handle extreme loads with minimal flex, such as arms, structural brackets, or drivetrain elements where rigidity is critical. While it doesn’t match the weldability or formability of 5052 or 6061, its strength-to-weight ratio is among the best of any aluminum alloy used in robotics. Although its corrosion resistance and machinability are rated as average to good, 7075 is not recommended for welded parts. It can be anodized, though with less consistency than 6061. Its lack of weldability makes it more suitable for bolted or riveted assemblies rather than fully custom-welded structures. ### Physical Properties of 6062 | | -O | -T6 | -T651 | -T73 | -T7351 | | ----------------------------- | ------------------------------------ | --------------------------- | ---------- | ---------- | ---------- | | **Density** | 0.1 lb/in3 | 0.1 lb/in3 | 0.1 lb/in3 | 0.1 lb/in3 | 0.1 lb/in3 | | **Ultimate Tensile Strength** | max. 40 ksi(bare); max. 39 ksi(clad) | 83 ksi(bare); 76 ksi (clad) | 80 ksi | 72.2 ksi | 73.2 ksi | | **Yield Tensile Strength** | max. 21 ksi | 73 ksi(bare); 67 ksi(clad) | 67 ksi | 63.1 ksi | 63.1 ksi | | **Fatigue Strength** | 18 ksi | 23 ksi | 23 ksi | 20.8 ksi | 21.8 ksi | | **Shear Strength** | 22 ksi | 48 ksi(bare); 46 ksi(clad) | 48 ksi | 42.5 ksi | 43.5 ksi | | {% endtab %} | | | | | | | {% endtabs %} | | | | | | # Steel Alloys {% tabs %} {% tab title="1008 Steel" %} Cold-rolled steel is a popular material for FTC teams who need strong, precise, and easily workable components. It starts as hot-rolled steel but undergoes additional processing at room temperature, which refines the surface finish, increases dimensional accuracy, and slightly boosts its strength and hardness. Compared to hot-rolled steel, cold-rolled steel has cleaner edges and tighter tolerances, making it easier to use in parts that require exact fits or precise bending. These properties make it ideal for custom brackets, mounts, or other fabricated components where strength and consistency are critical. Mild steel, a common form of cold-rolled steel, is widely used by prototyping teams and builders for its ease of machining, welding, and forming. If you're looking for a reliable material that combines strength with workability, cold-rolled carbon steel is a dependable choice for many FTC fabrication needs. ### Physical Properties of 1008 Alloys

Characteristics		5052-H32	5052-H34
Density	0.098 lb/in3	0.098 lb/in3	0.098 lb/in3
Ultimate Tensile Strength	28 ksi	33 ksi	38 ksi
Yield Tensile Strength	13 ksi	28 ksi	31 ksi
Fatigue Strength	16 ksi	17 ksi	18 ksi
Shear Strength	18 ksi	20 ksi	21 ksi

{% endtab %} {% tab title="A36 Steel" %} A36-HRPO steel is a versatile and durable material used by teams that need strong structural parts with improved surface finish. It begins as standard hot-rolled steel, but undergoes a pickling process to remove surface scale, followed by an oil coating to prevent rust and improve handling. While not as dimensionally precise as cold-rolled steel, A36-HRPO retains the strength and toughness of hot-rolled steel while being easier to work with due to its cleaner surface. This makes it well-suited for cutting, welding, and basic fabrication tasks, especially when extremely tight tolerances are not required. For FTC teams building frames, brackets, or support structures that need strength without sacrificing manufacturability, A36-HRPO provides a reliable middle ground—offering solid mechanical performance along with easier post-processing compared to untreated hot-rolled steel. ### Physical Properties of 1008 Alloys

Characteristics		5052-H32	5052-H34
Density	0.098 lb/in3	0.098 lb/in3	0.098 lb/in3
Ultimate Tensile Strength	28 ksi	33 ksi	38 ksi
Yield Tensile Strength	13 ksi	28 ksi	31 ksi
Fatigue Strength	16 ksi	17 ksi	18 ksi
Shear Strength	18 ksi	20 ksi	21 ksi

{% endtab %} {% endtabs %} # Stainless Steel Alloys {% tabs %} {% tab title="304-2B" %} 304 stainless steel is a strong, corrosion-resistant material commonly used in projects where long-term durability is essential. It is one of the most versatile stainless steels available, offering excellent weldability, good formability, and resistance to rust and oxidation. For FTC teams, laser-cut 304 stainless steel can be a reliable option for components exposed to moisture, wear, or outdoor conditions. Its corrosion resistance makes it especially useful for parts that must maintain strength and appearance over time, such as structural supports or hardware on demo robots used outside the competition environment. While it is heavier and more difficult to machine than aluminum or mild steel, 304 stainless is unmatched in durability and cleanliness. It's widely used in industries like food service, marine construction, and architecture for the same reasons. For applications requiring even higher corrosion resistance—such as exposure to saltwater or chemicals—316 stainless steel may be a better alternative, offering enhanced protection in the harshest environments. {% endtab %} {% endtabs %} # Titanium Titanium is an advanced engineering material known for its exceptional strength-to-weight ratio, making it a premium choice in aerospace, defense, and high-performance applications. Titanium sheets are significantly stronger than aluminum while weighing about 45% less than steel, offering excellent mechanical performance without unnecessary weight. For FTC teams, titanium is an interesting—though niche—option. Its standout features include: | Advantages | Disadvantages | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | |

High Strength-to-Weight Ratio: Titanium is nearly as strong as some steels but much lighter, making it useful when you need durability without adding excessive mass to your robot.
Corrosion Resistance: Titanium naturally resists rust and oxidation, making it ideal for environments with high moisture, exposure to elements, or even chemically corrosive conditions.
Temperature Resistance: Aerospace-grade titanium alloys can withstand extreme heat, which makes them ideal in contexts like high-speed motors or thermal isolation plates (though rare in FTC).
Biocompatibility: Although not relevant to FTC, titanium is used in medical devices for its compatibility with the human body—a testament to its safety and chemical stability.
Long-Term Durability: It doesn’t fatigue or wear down easily, so components made from titanium are built to last over many seasons or repurposings

Cost: Titanium is expensive—significantly more than aluminum or steel. For most FTC teams working with limited budgets, this is a major limiting factor.
Difficult to Machine: Titanium is notoriously tough on tools. It requires specialized equipment and slower cutting speeds, making it less practical for teams without access to advanced fabrication tools like CNC mills or waterjets.
Limited Availability in FTC Scale: It’s less commonly available in standard robotics formats (like extrusion profiles or pre-cut brackets), and sourcing custom titanium parts often takes more time and effort.
Weight Compared to Aluminum: While it’s lighter than steel, titanium is still heavier than aluminum, which is typically a better material when weight savings is the top priority.

| # Carbon Fiber Carbon fiber is a high-performance composite material made from woven strands of carbon atoms, typically reinforced with resin. It belongs to a class of materials known as **fiber-reinforced plastics** and is formed by weaving carbon filaments into fabric, cutting it into shape, infusing it with resin, and curing it using processes like carbonization or graphitization. The result is an incredibly strong, lightweight material with one of the highest strength-to-weight ratios of any substance used in manufacturing. | Advantages | Disadvantages | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | |

Exceptional Strength-to-Weight Ratio: Carbon fiber is stronger than steel and significantly lighter, making it ideal for parts where both rigidity and low mass are essential.
High Modulus and Tensile Strength: With tensile strengths around 4,000 MPa and a modulus of \~400 GPa, it performs extremely well under load, especially in tension.
Chemical and Corrosion Resistance: Carbon fiber does not rust or degrade under most environmental conditions, making it suitable for use outdoors or in humid climates.
Thermal and Electrical Properties: It is resistant to high temperatures and, depending on the resin used, can be made electrically conductive—useful in grounding or shielding applications.
No Fatigue or Creep: Carbon fiber holds its shape over time even under constant stress, making it reliable in long-term, load-bearing designs.

High Cost: Carbon fiber is still expensive compared to aluminum or steel, limiting its use to specialized parts where weight reduction or stiffness are absolutely necessary.
Brittleness: While strong, it can be brittle—meaning it doesn’t deform before breaking. If overloaded, it may snap without warning.
Difficult to Machine: Carbon fiber is abrasive and wears down tools quickly. Cutting it typically requires carbide or diamond-coated tooling, and dust from cutting is hazardous to breathe.
Layer Direction Matters: Unlike metals, carbon fiber is anisotropic—it’s stronger in the direction of the fibers. Improperly oriented layers can lead to unexpected weak points.
Delamination Risk: Improper bonding or damage to the laminate layers can cause delamination, reducing strength and integrity.

| #### When to Use It in FTC: Carbon fiber is best suited for ultra-lightweight structural parts, such as arm extensions, sensor mounts, or camera booms, especially when weight is a design constraint. While not common due to cost and machining needs, carbon fiber can offer a performance edge if used thoughtfully and fabricated with care. # Tolerances Proper tolerancing is essential for ensuring parts fit correctly. If a hole is designed to be exactly 1/4” for a dowel pin and cut using a waterjet or laser cutter, the fit may be inaccurate. * Waterjets produce tapered cuts, making the hole too small, while laser cutters often cut on the line, resulting in a slightly oversized hole. * Traditional CNC machines, like mills or lathes, achieve much tighter tolerances when properly configured. * Similarly, FDM 3D printing introduces dimensional inaccuracies due to extrusion variations, thermal expansion, and layer adhesion inconsistencies. Factors like nozzle diameter, print speed, and material shrinkage can cause holes to be slightly larger or smaller than intended.

Slip Fit

A slip fit is a type of clearance fit where parts can slide or "slip" together without force. This is useful when components need to be assembled and disassembled easily, such as shafts in bushings or spacers on bolts. In FDM 3D printing, achieving a reliable slip fit can be difficult due to inconsistencies in extrusion and dimensional accuracy. As a rule of thumb, a clearance of 0.2–0.5 mm around the mating part diameter often results in a functional slip fit, but this varies by printer, material, and orientation. Printing test pieces with incremental offsets is the best way to dial in the right gap for your printer and application.

Press Fit

A press fit, or interference fit, is when two parts are designed to be slightly larger than the other, requiring force to assemble. This creates a tight, often permanent connection without adhesives or fasteners—common for installing bearings, gears, or dowel pins. With FDM printers, reliable press fits are harder to achieve due to print variability, so testing different offsets is critical. A typical starting point is designing the hole 0.1–0.3 mm smaller than the shaft or insert. Heat can also assist in assembly: gently heating the printed part (e.g., with a heat gun) can help expand the hole slightly for a cleaner press.

Structural Backlash

Backlash is the unwanted play or looseness in a mechanical system, typically associated with gears, but it can also occur when two or more components are bolted or mounted together imprecisely. In assemblies involving 3D-printed parts or laser-cut panels, bolt holes that are too large can introduce slop between parts, affecting structural integrity and precision. To minimize backlash in mounted components, parts should be designed with tighter hole tolerances and, where possible, use dowel pins or alignment features to ensure consistent positioning. For motion systems, especially those involving belts or gears, minimizing backlash is critical for repeatable movement and accuracy. See: gear backlash

Manufacturing Tolerances

A common way for teams to deal with prints interacting with each other and hardware is to form a table with a list of commonly used hole sizes for your various applications and then use these hole sizes in their CAD. Numbers depend on your printer and nozzle size, so we would recommend making test prints to see how hardware can fit best in order to form this table. An example test print would be a print with a 2.8mm, 2.9mm, 3.0mm, 3.1mm, and 3.2mm hole to see which best creates an M3 through hole. This method is generally acceptable if kept well maintained and updated per printer, but it does mean that you have inconsistent hole sizes in CAD that would seem arbitrary to anyone looking at your team’s CAD.

# 3D Printing Optimizing 3d Print Machining for FTC A 3D printer creates parts by printing a part in many layers. There are many different types of 3D printers that all use different methods for printing their layers; the most common examples are [FDM](/manufacturing-and-assembly/additive-manufacturing/3d-printing/fdm), [SLA](/manufacturing-and-assembly/additive-manufacturing/3d-printing/sla), and [SLS](/manufacturing-and-assembly/additive-manufacturing/3d-printing/sls). 3D printing can be used to create parts that have complex geometry that would be impossible to create on a mill or other machine. # FDM The most common 3d printing method **FDM (Fused Deposition Modeling) >** A 3D printing method in which a thermoplastic [filament ](/design-style/optimizing-design-for-3d-printing/filaments)is melted and extruded through a nozzle to print an object layer by layer. This is the most common type of 3D printer because of its affordability, ease of use, and versatility. \ There are two types of FDM Printer: Bedslinger and Core XY.

What is a Bedslinger Printer?

In a bedslinger printer, the print head moves along the X-axis and sometimes the Z-axis, while the print bed moves back and forth along the Y-axis. This relatively simple system has contributed to its popularity, especially among hobbyists and beginners.

What is a Core XY Printer?

The CoreXY mechanism is a type of 3D printer design known for its lightweight and fast-moving print head. The defining characteristic of CoreXY is that the belts crisscross, allowing the print head to move independently of the print bed, which remains stationary during the printing process.

*Bambu Lab X1-Carbon with AMS (*Automatic Material System)


	Bed Slinger	Core XY
Price	Generally cheaper due to lower material cost and simpler design.	Generally, more expensive due to the complexity and cost of high-quality materials.
Maintaince	The design is simpler, making them easier to build, maintain, and repair.	The assembly and maintenance are complex, requiring regular upkeep.
Print speed	Slower due to the movement of the entire bed.	Faster due to the stationary motors and lighter moving parts.
Quality	The moving bed causes more vibration, which creates lower-quality prints.	It minimizes vibration-induced errors, leading to highly accurate prints
Size of bed	As the size of the print bed increases, the issues with speed and vibration become worse.	The movement along the X- and Y-axes allows for larger prints.

# SLA **SLA (Stereolithography)>** A 3D printing method that uses a laser to cure layers of a liquid photopolymer resin together. This is often used to create high-quality, accurate prints with smooth surfaces and intricate details. Using an SLA 3D printing gives a versatile range of materials available.
Depending on the formulation and chemistry, some resins can be leveraged to produce pure silicone, polyurethane, or ceramic parts. Resin 3D printing also offers the broadest spectrum of biocompatible materials, opening up doors in end-use products, medical equipment, 3D printing at the point of care, and medical procedure innovation. **How Does SLA 3D Printing Work? >** SLA 3D printing uses a light source to cure liquid resin into three-dimensional objects by exposing a vat or tank of resin to a light source, which hardens it

# SLS **SLS (Selective Laser Sintering)>** A 3D printing method that uses a laser to fuse powdered materials, usually nylon, together to create parts. This process is known to create strong, durable parts with complex geometries. **How Does SLS 3D Printing Work? >** * Printing: In this 3D printing process, a thin layer of powder is spread over a platform in the build chamber, preheated to just below its melting point. A laser then selectively heats specific areas, fusing particles to form solid parts while the surrounding powder acts as support. The platform lowers after each layer, repeating the process until the part is fully formed. * Cooling: After printing, the build chamber needs to slightly cool down inside the print enclosure and then outside the printer to ensure optimal mechanical properties and avoid warping in parts. * Post-processing: The finished parts need to be removed from the build chamber, separated, and cleaned of excess powder. The powder can be recycled and the printed parts can be further post-processed by media blasting or media tumbling.

# Into to CNC Machining All Types of precision subtractive machining Computer Numerical Control (CNC) machining is a manufacturing technique that uses computer software to control the movement of machinery and tools. This technology can manage a wide variety of advanced machines, including grinders, [lathes](/manufacturing-and-assembly/subtractive-manufacturing/lathes), [mills](/manufacturing-and-assembly/subtractive-manufacturing/cnc-mills), and CNC routers, enabling complex three-dimensional cutting operations with just one set of instructions.
Once a CNC system is started, the programmed instructions guide the tools and equipment to perform the required operations—similar to how a robot functions. CNC programming involves a code generator that typically assumes the machines will operate without fault, although errors can increase when cutting in multiple directions at once. The positioning of each tool is determined by a sequence of commands known as the part program. \ Traditional numerical control machines received instructions via punch cards, while CNC machines use keyboards to input programs directly into a computer. These programs are stored digitally and can be written and modified by programmers. CNC systems offer greater computing power and flexibility, allowing updates or new commands to be added to existing programs through code revisions. Additional CNC References \
# CNC Mills CNC milling machines operate using programmed commands made up of letters and numbers, which guide tools along various paths. These programs can be based on standard G-code or custom languages developed by specific manufacturers. Basic CNC mills have three axes (X, Y, and Z), but more advanced models can include up to three additional axes for greater flexibility.

*Worthy Hardware's* *image of a CNC Mill*

# Laser Cutters The most common subtractive machining in FTC ## **Types of Laser Cutters** * ### Diode Lasers These compact and affordable cutters use a small laser diode and are best suited for cutting paper, cardboard, and thin wood. They are useful for quick prototypes and engraving designs or team information. * ### CO₂ Lasers CO₂ machines use mirrors to direct a high-powered beam from a laser tube. These cutters are enclosed and capable of cutting wood and many plastics. They are particularly useful for making functional custom parts for FTC robots. * ### Fiber Lasers Fiber lasers combine multiple laser diodes into a fiber optic cable, allowing them to cut metal with high precision. These machines are typically expensive and have small working areas, making them less common among FTC teams.

## **Materials You Can Cut** * ### Wood Thin wood sheets are easily cut and great for prototypes or low-stress parts. Some types of wood may release fumes or present fire risks depending on their composition. * ### Acrylic Acrylic is popular for decorative elements and lightweight guides. While easy to laser cut, it can crack under mechanical stress. * ### Delrin (Acetal Delrin is a strong, versatile plastic that can be cut safely with proper ventilation. It is well-suited for functional robot components such as motor mounts and structural inserts. ## Materials You Should Avoid * ### PVC Releases toxic gases that are harmful to both users and the machine. * ### Polycarbonate Discolors and burns rather than cuts cleanly, while also emitting harmful fumes. * ### ABS and HDPE These plastics tend to melt instead of producing clean cuts. * ### Unidentified Plastics Different plastics can look similar but behave differently under a laser. Avoid cutting any plastic unless you’re sure it’s safe.
# Plasma Cutters These machines use a plasma torch to cut through materials, typically metals. The plasma is generated by combining compressed air with electrical arcs to produce the heat and speed required for cutting.
# Water Jet Water jets use high-pressure streams of water—sometimes mixed with abrasive substances—to cut hard materials like metal or granite. This method is ideal for materials that can’t withstand the heat of traditional cutting techniques. Industries such as aerospace and mining use water jets for precise, heat-free cutting that preserves the material’s properties. # Lathes CNC lathes rotate workpieces and use indexable tools to perform precise cuts. This technology enables high-speed, accurate machining of complex shapes that would be difficult or impossible to achieve manually. Like mills, CNC lathes typically use G-code or proprietary programming, though they usually operate on two axes—X and Z. # Threading and Tapping Fasteners are critical in FTC manufacturing, holding together everything from chassis rails to motor mounts. Common FTC fasteners include socket head screws, hex bolts, nuts, washers, and standoffs—most using **M4** threads.

Thread Tapper for a Drill press, used to thread holes

Threaded Plate from Gobilda - SKU: 2803-0023-0007

Threading refers to the spiral grooves inside a hole or on the outside of a shaft that allow a fastener to grip and hold. In FTC, this is usually done by **tapping** holes—cutting threads into a drilled hole using a tool called a **tap**. Tapping allows you to secure fasteners without needing a separate nut, which saves weight and space. * **Tapping Holes**: Start by drilling with the correct *tap drill size* (e.g., #36 drill for 6-32 threads). Use a tap handle and cutting fluid if possible, turn slowly, and back off frequently to avoid breakage. * **Threaded Inserts**: If you’re working with 3D-printed parts, threaded inserts (heat-set or press-fit) provide durable threads that won't strip out under torque. # Fasteners Screws are one of the most commonly used fasteners in FTC and are essential to structural integrity and modularity. Choosing the right screw type can affect weight, strength, ease of maintenance, and durability under vibration.

Screw Material Guide

* **Steel (Black Oxide or Zinc-Plated)**\ Strong and affordable. Black oxide provides mild corrosion resistance. Commonly used in frame and drivetrain construction. * **Stainless Steel**\ Corrosion-resistant and durable but heavier. Good for exposed or long-lasting assemblies. * **Aluminum Screws**\ Extremely lightweight but weaker. Rarely used outside of aerospace-style applications or weight-optimized robots. * **Nylon Screws**\ Lightweight and non-conductive. Useful for electronics mounting, but unsuitable for load-bearing use.

### Threadlocker **Threadlocker** is a type of adhesive that’s applied to screw threads to prevent loosening due to vibration or shock. FTC robots undergo constant motion—especially in drivetrains and arms—so threadlocker is essential for keeping screws from backing out during matches.

* **Blue Threadlocker (Removable)**\ This is the most commonly used threadlocker in FTC. It prevents loosening but still allows you to remove the screw later with hand tools. Ideal for drivetrain components, mounting plates, motor screws, and anywhere vibrations are common. * **Red Threadlocker (Permanent)**\ This is much stronger and usually requires heat to remove. It’s *not recommended* for FTC unless you're securing something you **never** plan to take apart (like press-fit bearings or permanent inserts). * **Purple Threadlocker (Low Strength)**\ Good for small screws (like M2 or M3) or delicate parts. Easier to remove than blue but still provides some vibration resistance. ### Washers {% tabs %} {% tab title="Flat Washers" %} The most common washer type. They distribute the screw’s force over a larger area, which protects softer materials like plastic or aluminum from being crushed or deformed. Also useful in slotted holes to prevent slipping. {% endtab %} {% tab title="Lock Washers" %} Designed to resist loosening. They come in split-ring or star (internal/external tooth) varieties. These are **less common in FTC**, where blue threadlocker or nylon-insert nuts are typically preferred. {% endtab %} {% tab title="Fender Washers" %} Extra-large washers that spread force across a wide surface. Useful for mounting electronics, covering oversized holes, or protecting soft materials like polycarbonate. {% endtab %} {% tab title="Nylon Washers" %} Non-conductive and slightly compressible. Used for isolating electronics or protecting fragile surfaces. Common in mounting sensors, batteries, or REV hubs. {% endtab %} {% endtabs %}

# Tooling ### Allen Keys Used for nearly every screw in FTC. Make sure to have metric 2.5mm and 3mm depending on the hardware you use. Get T-handle or ball-end hex keys for comfort and speed. Ball end Allen Keys are a gift from heaven, they allow you to screw in screws from awkward angles, for when you didn't think the mounting through... ### Screwdrivers A good set of **Phillips and flathead** drivers is still useful for electronics, mounts, and quick fixes. Consider stubby or precision drivers for tight spaces. The flathead screwdriver can also double as a pry bar and as a wedge when disassembling old systems. ### Pliers A few types are worth having: * **Needle-nose pliers** for small parts and tight spots. * **Slip-joint or lineman's pliers** for general gripping. * **Flush cutters** for zip ties and small wires. * **Locking Wrench** is a great tool to remove siezed, crossthreaded, or stripped fasteners # Design Style The design of a robot is more than just putting parts together. It's about how all the parts work as a system. The way you approach your robot’s design has a huge impact on how easy it is to build, iterate, fix, and compete with.

This section dives into the principles that make FTC robots clean, consistent, and competition-ready. Whether you're designing your first bot or refining your 10th, having a clear design style improves reliability and efficiency across the board. Clean, modular, and serviceable robots are not accidents. Every benefit is the result of intentional design choices. Every bracket, wire, and spacer should have a purpose, and no mechanism should be harder to reach than necessary. In this section, we break down the visual and structural design elements that make great FTC robots stand out, including standard spacing conventions, wiring discipline, fastener choices, and a mindset for mechanical clarity. Understanding and applying a consistent design language also makes it easier for new team members to contribute, CAD reviewers to catch mistakes, and for everyone to debug or disassemble the robot during matches or inspections. It even helps judges quickly understand how your robot works. Here, you'll find breakdowns on visual cleanliness, standardization, modularity, wire management, and construction techniques that are easy to maintain and scale. These best practices are not just about aesthetics—they’re about performance, safety, and professionalism. # Optimizing Design for 3D Printing 3D printing offers huge advantages in FTC; custom parts, quick iteration, and geometric flexibility. However, to truly benefit, parts must be **designed specifically for printing**. Poorly designed models can waste time, filament, and lead to mechanical failures. Designing for 3D printing isn’t just about making a part printable—it’s about making it strong, efficient, and cleanly manufactured *on your specific printer and material*. ### [**Part Orientation and Layer Strength**](/design-style/optimizing-design-for-3d-printing/orientation-and-layer-strength) The first rule of design-for-printing is understanding that **layer lines are the weakest axis**. In FDM printers, parts are built up in layers, so a vertical cylinder is much more likely to split along layer lines than a horizontally printed one. Design your part so that the direction of expected load lines up with the part’s strongest axis—parallel to the print bed. A good rule of thumb is: **don’t cantilever parts along the Z-axis unless absolutely necessary**. ### [**Wall Thickness and Support Avoidance**](/design-style/optimizing-design-for-3d-printing/wall-strength-and-shells) Thin walls may save weight, but if your walls are too thin to properly accommodate your printer’s nozzle (typically 0.4 mm), print quality and strength will suffer. In general, walls should be **multiples of your nozzle width** (e.g., 0.8 mm, 1.2 mm) and support at least 3 perimeter shells for structural parts. Use **chamfers** instead of sharp overhangs or bridges, and try to orient parts to print without support whenever possible—it reduces post-processing time and improves finish quality. ### [**Fillets, Chamfers, and Strength**](/design-style/optimizing-design-for-3d-printing/load-distribution) Sharp corners are stress concentrators and often lead to cracks or delamination. Add **fillets or chamfers** on all internal corners to distribute stress more evenly and help layer adhesion. Rounded edges also improve print aesthetics and reduce warping, especially with materials like ABS or Nylon. For structural parts, add **ribs** and **gussets** instead of just increasing wall thickness—these features strengthen the part without adding unnecessary mass or filament usage. ### [**Lightweighting and Print Efficiency**](/design-style/weight-savings-pocketing) Solid blocks of plastic are rarely necessary. Use **internal lattice patterns, cutouts, and hexagonal pockets** to remove mass without losing structural integrity. Infill percentage can also be reduced (30–40% is often plenty for FTC parts) to save time and material. For parts where stiffness matters, consider using higher walls and perimeters instead of denser infill. ### [**Material-Specific Design**](/design-style/optimizing-design-for-3d-printing/filaments) Different materials behave differently. **PLA** is rigid but brittle, **PETG** is flexible and strong but warps more, and **Nylon** is tough and fatigue-resistant but harder to print accurately. Your part design should reflect the material it’s made from—snap fits and flexing clips work better in Nylon or TPU, but rigid mounts and brackets are best in PLA+ or PETG. *** By intentionally designing your parts with 3D printing in mind—considering orientation, tolerances, wall thickness, and material—you’ll get cleaner prints, stronger parts, and fewer headaches. Great FTC teams don’t just use printers—they **design for them**. # Filaments FDM 3D printers use material called filament. It's a thin plastic wire that comes on a spool and is fed into the printer. Most filament is plastic, however, there are also metal, composite and rubber filaments. {% tabs %} {% tab title="Common Filaments" %} For almost every part that needs to be 3D printed for FTC, PLA and/or PETG will meet all the needs for strength, durability, and aesthetics. These two filament types are by far the easiest to print, and are sold by many manufacturers for reasonable prices. Most of the other filaments here offer very specific advantages (like TPU) that come at the cost of effort, time, and money. | | | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------- | |

PLA (Polylactic Acid) >

The most common 3D Printing filament is polylactic acid, or PLA. It is a plastic made from biological sources like corn starch and sugar cane. PLA is stiff but more brittle than other filament options and tends to have little to no warp when printing. PLA is well suited to the majority of robot parts, but it may not hold up well to shock loads (impacts to parts), and as such, parts should be designed accordingly.

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PETG (Polyethylene Terephthalate Glycol) >

PETG can be described as a strength upgrade to PLA. It is not difficult to print, but it often has noticeably more stringing and other minor artifacts. While it technically has a lower tensile strength than PLA, it is far less brittle and withstands impacts better, through slight flexing. It is a great option for FTC parts that need to be impact resistant, where PLA will not suffice. Its higher temperature resistance also means it won’t warp in a high ambient temperature, such as a hot car.

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PETG-CF (Carbon Fiber Reinforced PETG) >

PETG-CF is a PETG filament that has been reinforced with short strands of carbon fiber. This results in a material that is stiffer and lighter than regular PETG, with reduced flex and greater dimensional stability. Parts printed with PETG-CF are stronger and more rigid, making them ideal for structural parts where PLA or PETG may bend or deform. However, this filament is abrasive and will wear out brass nozzles quickly, so a hardened steel is highly recommended. Surface finish is usually matte and very appealing, but the filament is more expensive and slightly more brittle than regular PETG.

| {% endtab %} {% tab title="Uncommon Filaments" %} These filaments are less commonly used than those listed above, but can still find plenty of use cases on an FTC robot. These are usually used due to specific material properties such as flexibility or durability. These often come however, with substantial obstacles for printing that prevent some printers from printing them out of the box, along with sometimes being significantly more expensive. | | | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | |

ABS (Acrylonitrile Butadiene Styrene) >

ABS used to be the standard filament for printing before PLA became commercially available. You’ve probably used ABS before in LEGO® pieces. It can withstand high loads and is quite ductile. This comes at the cost of printing difficulty, where an enclosure is often necessary to raise the ambient temperature and prevent severe part warping. The strength improvements over PLA can be more easily found in PETG, so ABS parts are not as common in FTC. ABS is quite affordable, though, sold at the same prices as PLA.

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TPU (Thermoplastic polyurethane) >

TPU is a common printing filament that is widely used for its flexible material properties. This allows one to create printed parts that can easily flex and bend. Sold under many different durometers (a measure on the Shore Hardness Scale of the hardness/flexibility of a material), TPU/TPE’s high impact resistance and layer adhesion make it not only a versatile filament, but an extremely durable one. In FTC, teams use TPU/TPE in roles such as printed intake flaps in place of a tube, as well as custom belts for low-load applications.

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Nylon-Based Filaments >

Nylon is a high-performance engineering plastic known for its excellent strength, flexibility, and wear resistance. It can absorb shock loads well and has great layer adhesion, making it useful for FTC parts like gears, spacers, or slide components that need to resist abrasion and impacts. Nylon does tend to absorb moisture from the air (hygroscopic), which can compromise print quality unless dried before use. It also tends to warp significantly and may require an enclosure. Despite the print challenges, it is one of the most durable and functional materials available for FDM printers.

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Polycarbonate-based Filaments >

Polycarbonate (PC) is one of the toughest materials available for desktop 3D printing. It boasts excellent strength, impact resistance, and high temperature tolerance—ideal for parts exposed to mechanical stress or heat. PC is significantly stronger than PLA, PETG, or even ABS, but it is also one of the most difficult materials to print, requiring high nozzle temperatures (over 270°C), a heated bed, and often an enclosure to prevent cracking and warping. Due to these challenges, it is typically only used when its high-performance properties are necessary.

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Glass-based Filaments >

Glass-filled filaments are standard materials like Nylon or PETG that have been reinforced with short strands of fiberglass. These composites increase rigidity and reduce material shrinkage, resulting in parts with very high dimensional accuracy and stability. They are excellent for structural applications where flexing is undesirable. Similar to carbon fiber filaments, glass-filled filaments are abrasive and require a hardened nozzle. While they are not as widely used in FTC due to cost and print difficulty, they can be invaluable for producing strong, precise brackets and mounts under high loads.

| | {% endtab %} | | | {% endtabs %} | | # Orientation and Layer Strength UNDER CONSTRUCTION *\[Illustration: Same bracket printed vertically vs. horizontally, showing layer lines and failure direction]*\ **CAD Model**: `Simple L-Bracket.stl` (with load direction arrow annotations) **Key Takeaway**: Always print structural parts so that **layers run along the direction of expected stress**, not across it. Vertical prints fail faster at stress points. # Wall Strength & Shells UNDER CONSTRUCTION *\[Illustration: Cross-section of part showing 2-wall vs. 4-wall shell strength comparison]*\ **CAD Model**: `Chassis Spacer_CrossSection.step` **Key Takeaway**: Wall thickness should be **multiples of your nozzle width** (usually 0.4 mm). For FTC-grade strength, **use 3+ outer walls and 25–40% infill** minimum. # Load Distribution UNDER CONSTRUCTION *\[Illustration: Gusseted support bracket vs. non-supported version showing stress points]*\ **CAD Model**: `90DegArmWithGusset.stl` **Key Takeaway**: Internal **fillets improve stress distribution** and reduce delamination. Chamfers also reduce warping at base edges and make parts cleaner to print. # Weight Savings (Pocketing) **Pocketing >** To reduce weight without compromising structural integrity, teams often incorporate pocketing patterns into parts, a technique commonly called pocketing or lightening. These pockets remove excess material while maintaining the structural integrity. When designing pockets to reduce weight, it's important to consider the forces the part will experience and the key areas needing extra support, like bearing and bolt holes. A good pocketing design keeps the part strong while making it lighter, ensuring it works reliably and lasts longer.

FTC 17670 - Our First Parallel Plate Chassis Design used at NJ State Championship

**Designing for Pocketing Patterns >** When creating pocketing patterns, remember that triangles are the strongest shape. Sharp corners should be avoided, as they can lead to cracks or tears. Adding rounded edges helps prevent these issues. When cutting parts on a waterjet or a laser cutter, the rounds can be almost any size.
It is best to wait until the very end of your design to create patterns, otherwise, you will likely waste a lot of time when changing things on your parts. *** **Types of Pocketing Patterns >** **Triangles >** As stated previously, triangles are the strongest shape. Triangles are also typically used on box tubes that are less than 2 inches in dimension, since milling isogrid on parts smaller than that usually requires small endmills and increases machining time.

**Circles >** Circles are the easiest pocket patterns to machine as they can be machined on a drill press, if necessary. Circles are also easy to draw and can even make parametric. Many teams end up drilling circular holes in their robot late in the build season, when they realize their robot is overweight. **Pocketing non-standard part >** For parts with multiple bearings and bolt holes, it's important to connect them to the rest of the structure using struts, allowing loads to be evenly distributed. Ensure there's enough material surrounding the bearings, bolt holes, and the outer edges to provide proper support. The strongest approach is to arrange the struts in a triangular pattern. If you have a large, open rectangular section, consider adding a strut to divide it into two triangles for better load distribution and stability.

Sohm Shah from 11285 PATENT PENDING *pocketed parallel plates.*

A way to configure your pocketing pattern is to use a generator, such as [Voronoi Editor](https://voronoi-editor.web.app/), which creates optimized cutout patterns in a part. # How to Design a Clean Robot A robot can function just fine while still being cluttered, difficult to maintain, or even unsafe. “Clean” design goes beyond looks—it's about structure, serviceability, and thoughtful planning. A clean robot is easier to fix, debug, and upgrade. Judges and alliance partners notice. Clean design demonstrates engineering maturity. #### Why Cleanliness Matters * **Serviceability:** Clean designs allow for quicker swaps, easier cable tracing, and faster troubleshooting between matches. * **Consistency:** A well-structured robot is easier to program because sensors, mechanisms, and encoders behave predictably. * **Judge Appeal:** A tidy robot signals that your team understands engineering best practices and cares about quality. #### Common Signs of a Messy Robot * Wires crossing over mechanisms or dangling loosely * Screws that are impossible to reach without full disassembly * Mechanisms attached at awkward angles without alignment * Zip ties, tape, and hot glue holding critical components #### Hallmarks of a Clean Build * Thoughtful cable routing with strain relief and bundling * Standardized hardware sizes and symmetrical placement * Easy access to high-maintenance parts like batteries and motors * Components mounted squarely and parallel to each other # Modularity Building your robot with modular subsystems saves hours during testing and events. Modularity means each mechanism can be treated like a black box—built, tested, and repaired independently. Standardization ensures that parts and tools are consistent across your design. #### What Is Modularity? A modular subsystem is self-contained: * It bolts on with a few screws or brackets * Has a single set of wires or cables going in/out * Can be removed without disturbing unrelated systems **Examples:** A fully removable arm module, drivetrain pods, intake trays, or even pre-wired electronics boards. #### Benefits of Modularity * **Faster Repairs:** Replace a broken part without taking apart the whole robot. * **Parallel Development:** Mechanical and electrical team members can work on different modules simultaneously. * **Easier Iteration:** Test different versions of a mechanism without redesigning the whole robot. * **Consistent Mounting:** Use standard hole spacings and brackets (e.g., 16mm grid, extrusion mounts). #### Standardization Tips * Use common motor types (e.g., all GoBILDA 312 RPM) * Stick to one bolt size per use-case (M4 for structure, M3 for electronics) * Use keyed motor shafts or set screw flats consistently * Design 2D brackets and spacers around common thicknesses (3mm, 6mm, etc.) # Standardization PAGE UNDER CONSTRUCTION # Wiring Good wiring doesn’t just look nice—it prevents damage, reduces electrical noise, and keeps your robot easy to service. Poor wire management is one of the top causes of robot failure in competition. #### Wiring Principles * **Secure:** No loose wires or plugs that can fall out or get snagged * **Labeled:** Each connection should be traceable and ideally labeled * **Bundled:** Use split loom, braided sleeving, or velcro to bundle similar wires * **Accessible:** Make sure every plug is reachable without full disassembly #### Best Practices * Run wires along the structure—not across open air * Use strain relief at all connectors (e.g., zip tie the wire to a nearby part) * Avoid sharp bends that can pinch or fatigue cables * Keep signal and power wires separate when possible #### Examples of Good Routing * A power distribution board mounted to a plate, pre-wired, and connected to the REV Hub with a short harness * Motor cables run through channels in extrusion or along inside faces of gussets * Sensors mounted on brackets with their wires zip-tied along an adjacent beam # Naming Conventions CAD files can become a mess faster than your pit table if you don’t stay organized. Clean file structure and naming make it easier for multiple people to collaborate and modify the design as it evolves. #### Naming Conventions Good names are: * **Descriptive** (e.g., `right_drive_motor_mount` vs. `part3`) * **Consistent** (stick to lower\_case\_with\_underscores or CamelCase—not both) * **Structured** by category: `drive_`, `intake_`, `arm_`, etc. #### Folder and Feature Management * Organize parts into folders by subsystem * Name sketches, features, and planes clearly (`sketch_belt_profile`, `plane_mount_face`) * Use labels or custom colors to differentiate moving vs. fixed parts #### Version Control * Use `V1`, `V2`, etc. in part names or folders when iterating * Archive old versions instead of deleting * Record design decisions in comments or a changelog #### Onshape Tips * Use Part Studios to group related geometry * Use Assembly tabs to simulate movement and fit * Use variable naming for constants like extrusion length, spacing, or hole offsets # Sheet Metal Sheet metal design involves cutting 2D flat parts—usually from aluminum or polycarbonate—and bending them to form rigid 3D structures. Common in professional manufacturing, this method brings high strength-to-weight ratios and sleek results to FTC when used with laser cutters, waterjets, or CNC routers. #### How It Works * Parts are designed in a flat form and cut from a sheet. * Bends are made with a brake, hand bender, or pliers (for thin plastic). * Holes, cutouts, and slots are added during cutting, enabling precise integration. #### Pros * **Strong and Lightweight:** Folded edges reinforce structural stiffness. * **Custom Fit:** Integrate mounting points, wire routing, and geometry directly into part design. * **Low Profile:** Flat geometry makes it ideal for tight packaging. #### Cons * **Requires Planning:** You must account for bend radii, reliefs, and K-factors (bend stretching). * **Tooling Needed:** Bending aluminum cleanly requires a brake. * **Not Modular:** Parts are purpose-built and difficult to reuse on other bots. #### FTC Tips * Use 5052 aluminum in 0.04–0.063" thickness for easy bending. * Design for *single-direction bends* to keep parts simple. * Avoid sharp 90° interior corners—use radiused slots to prevent stress cracks. * Polycarbonate sheet can be heat bent and is easier to prototype. # Plate and standoff construction A favorite among FTC teams, plate and standoff construction uses 2D-cut flat plates spaced apart using standoffs or stacked plastic spacers. It’s intuitive, easy to service, and perfect for custom drivetrains or slide guides. #### How It Works * Two parallel plates form the "walls" of a structure. * Standoffs, spacers, or bearings are used to connect and align them. * Motors, shafts, and other hardware are mounted between the plates. #### Pros * **Serviceable:** Remove screws to open the assembly like a sandwich. * **Strong and Rigid:** Parallel plates resist torsion well. * **Easy to Design:** Plates can be laid out in 2D and stacked. #### Cons * **Space-Hungry:** Can get bulky in tight robots. * **Heavy:** Metal plates and many screws/standoffs add mass. * **Limited Adjustability:** Mounting patterns are fixed after cutting. #### FTC Tips * Use ⅛” aluminum or ⅛”/¼” polycarbonate plates. * Design mounting holes on a 16mm grid to align with common FTC components. * Add inspection holes to see bearings and shafts inside. * Offset holes to match standoff centers—always model screw heads to check clearance. # Boxtube construction Tube-based construction uses square (or rectangular) extrusion as the main structure. It’s popular for building strong, minimal-friction drivetrains, arms, and linear slide supports. Teams often use aluminum tubing or extruded building systems like REV or GoBILDA. #### How It Works * Structural members are made from 1x1" aluminum tube or extrusion. * Plates, brackets, or gussets are bolted to the tube faces. * Components like slides or bearings ride along or inside the tubing. #### Pros * **Very Rigid:** Tubing resists bending, great for arms and frames. * **Modular Mounting:** You can tap into tube faces or use brackets. * **Efficient Use of Space:** Great strength-to-volume ratio. #### Cons * **Requires Precision:** Drilling/tapping holes straight is critical. * **Difficult to Modify:** Custom tube setups don’t allow sliding or quick realignment. * **Access Needed:** Tube interiors are hard to reach once closed off. #### FTC Tips * Use 1x1” 1/16” wall aluminum tubing (e.g., 6061-T6) for strong but light framing. * Tap ends for M3 or M4 screws using 3D-printed guides or jigs. * Clamp or bolt corner gussets for rigid 90° joints. * Consider nested ¾” tube inside 1” for telescoping mechanisms. # Slots and Tabs Slot and tab construction involves interlocking parts like a 3D puzzle. Tabs on one piece fit into slots on another, aligning the parts automatically. When glued, bolted, or clamped together, this method creates fast, rigid assemblies without complex tools. #### How It Works * CAD parts are designed with matching cutouts and tabs. * Cut from flat sheet stock (metal, polycarb, plywood). * Tabs insert into slots and are fastened with screws, rivets, glue, or welding. #### Pros * **Fast Assembly:** Self-aligning joints reduce the need for jigs. * **Repeatable:** Great for building multiple identical bots or testbeds. * **Good for Non-Metal:** Works well with plastic or wood prototypes. #### Cons * **Hard to Modify:** Once joined, the structure isn’t easily reconfigurable. * **Flex Risk:** Thin materials may wobble or deform under load. * **Cutting Precision Needed:** Slots and tabs must be toleranced correctly for your cutting process. #### FTC Tips * Add \~0.1–0.2mm clearance between tabs and slots depending on cutter type. * Use interlocking fingers or “keyed” features to lock parts rotationally. * Add fillets or dog-bones to inner corners to match laser/waterjet cut radius. * Secure tabs with nylon lock nuts or rivets—design so they sit flush to avoid snagging. # Introduction to Motion **Power transmission** is the system of components that transfers motion from your motors to the moving parts of your robot. The easiest way to think of it is how you get things like wheels, arms, or intake mechanisms to spin. In FTC, choosing the right transmission method can impact your performance, efficiency, reliability, and maintainability. This page provides an overview of common power transmission systems used in FTC, along with guidance on when and why to use each one. ### Common Power Transmission Methods Each of the following methods has its own strengths, weaknesses, and ideal use cases:


Chain and Sprocket	Pros: Allows flexible placement, strong under load Cons: Requires tensioning, can be noisy Use Cases: Drivetrains, arms, elevator mechanisms	/files/ZDwaGknedV4Bgcap2hpU
Belts and Pulleys	Pros: Quiet, lightweight, flexible layouts Cons: Can slip if not properly tensioned, lower load capacity Use Cases: Intakes, transfer systems, turrets	/files/sK3p6O3TqTqgvjGATBNi
Spur Gears	Pros: High efficiency, compact, precise Cons: Requires rigid mounting, sensitive to misalignment Use Cases: Drivetrains, linear slides, arms	/files/4V8LGhxIc8fWvaL8tXwa

Chain and Sprocket

Pros: Allows flexible placement, strong under load
Cons: Requires tensioning, can be noisy
Use Cases: Drivetrains, arms, elevator mechanisms

/files/ZDwaGknedV4Bgcap2hpU

Belts and Pulleys

Pros: Quiet, lightweight, flexible layouts
Cons: Can slip if not properly tensioned, lower load capacity
Use Cases: Intakes, transfer systems, turrets

/files/sK3p6O3TqTqgvjGATBNi

Spur Gears

Pros: High efficiency, compact, precise
Cons: Requires rigid mounting, sensitive to misalignment
Use Cases: Drivetrains, linear slides, arms

/files/4V8LGhxIc8fWvaL8tXwa

### Tutorials and Examples * [Designing a Custom Gearbox in Onshape](/intro-to-cad/level-2/b.-power-transmission-wip#examples) * [Chain Tensioning Techniques](https://www.youtube.com/watch?v=vi2FfGqCeGI) # Shafts # Bearings In any FTC robot, bearings are an essential part of a well-functioning power transmission system. They allow rotating shafts to spin smoothly, reduce friction, and maintain mechanical alignment between components. Without bearings, your robot's drivetrain, gearbox, or intake system would suffer from excessive wear, efficiency loss, and mechanical instability. When power is transferred from a motor to a mechanism—whether through gears, chains, belts, or shafts—bearings serve a critical role in supporting that motion. This page explores how bearings are used in power transmission systems, why they matter, and how to design with them effectively in your FTC robot. *** ### The Purpose of Bearings Bearings are designed to support loads and minimize friction between moving parts. In the context of power transmission, they are usually used to support rotating shafts or axles that transmit torque. When a shaft rotates under power, it naturally wants to shift, flex, or push against its mounting points—especially when side loads are applied by belts or chains. Bearings counteract these forces and allow the shaft to rotate freely while staying aligned with other components. Without bearings, the shaft would directly rub against plastic or metal plates, leading to high friction, poor efficiency, and eventual deformation of the mounting holes. Bearings eliminate this problem and drastically improve both the performance and lifespan of rotating systems. *** ### Bearings in Drivetrains and Gearboxes In drivetrains, bearings are most commonly used to support wheel shafts. Even if your motors are mounted directly to the drive wheels, any shaft that passes through the robot's frame should have bearings on both sides. This prevents the shaft from flexing under load and helps ensure consistent alignment between the motor, gears or sprockets, and wheels. In custom gearboxes, bearings are used to support each shaft that holds gears. At least two bearings should be used per shaft—typically one on either side of the gear cluster. This setup ensures the shaft remains parallel to others and prevents gear mesh misalignment. It also helps to isolate the motor from external loads, improving motor health and transmission reliability. *** ### Bearings in Chain and Belt Systems When chains or timing belts are used to transfer power, they introduce side loads on the shafts they connect to. Bearings are crucial in these cases to support the radial force caused by tension. For example, if a sprocket is mounted on a shaft driven by a motor, the tension in the chain can push or pull the shaft sideways. A pair of well-placed flanged bearings will support that shaft and allow it to spin freely under tension. If a system lacks proper bearing support, belts can cause the shaft to sag or misalign. This leads to power losses due to friction and can cause components like pulleys or sprockets to wear out quickly or even fall out of place. *** ### Types of Bearings Used in FTC The most common type of bearing in FTC is the **flanged ball bearing**. These typically have a ½” outer diameter and a 5mm or ⅛” inner diameter, depending on your shaft type. They’re designed to press-fit into metal or plastic mounting plates and are used for supporting through-shafts. The flange helps keep the bearing from sliding out of the hole. **Pillow block bearings** are another useful option when you need to support a shaft away from a structural plate. These are standalone bearing housings that mount to flat surfaces. They’re great for supporting long shafts, such as those used in drivetrains or lifting arms, but take up more space than flanged bearings. **Thrust bearings** are used when a shaft is under axial load—meaning the force is pushing along the length of the shaft instead of perpendicular to it. These are most often found in screw-driven elevators or rotating arms where a motor or gearbox is applying force along the shaft’s axis. Lastly, **plastic bushings** or sleeve bearings can be used in lower-load, lower-precision applications. These rely on low-friction materials like nylon or acetal and don’t contain rolling elements. While they’re simple and compact, they are much less efficient than ball bearings and are not recommended for high-load or high-speed power transmission. *** ### Best Practices for Using Bearings Whenever you are designing a power transmission system, make sure that each rotating shaft is properly supported by bearings. Ideally, a shaft should be supported by two bearings spaced apart to prevent wobble and reduce strain on the shaft and any connected gears or sprockets. For high-speed or high-load applications, this is absolutely essential. Bearings should be carefully aligned in CAD before manufacturing. Even small misalignments can cause friction and make the system bind. If you are using 3D printed or laser-cut parts, test your tolerances to make sure the bearing fits snugly without being too tight, which could deform the bearing or shaft. Use shaft collars or spacers to prevent axial movement of the shaft between bearings. A loose shaft can slide and cause inconsistent performance or component failure. For belt or chain-driven shafts, position the bearing directly under the pulley or sprocket to minimize bending loads. Finally, don’t rely on the motor alone to support a shaft. Doing so places side loads directly on the motor shaft, which can lead to internal damage or reduced efficiency. Bearings should always be used to support power transmission loads, especially when the output shaft connects to anything larger than a simple roller or gear. * [REV Robotics Bearing Guide](https://www.revrobotics.com/) * Designing for Bearings in Onshape * Linear Motion Systems # Sprocket and Chains # Pulley and Belts # Gears What are gears? Gears are toothed mechanical components that transmit motion and force between rotating shafts. They are crucial in controlling speed, torque, and direction in machines by interlocking and transferring energy efficiently. In *FIRST Tech Challenge*, gears are essential for designing and optimizing robot mechanisms. They help teams build drivetrains, arms, and manipulators that can move with precision and efficiency. By selecting the right [gear ratios](/transmitting-power/gears/gear-ratios), teams can balance speed and torque to improve their robot’s performance in competition. Gears come in many distinct shapes, each suited for different mechanical functions: {% tabs %} {% tab title="Common Gears in FTC" %} |

Spur Gear

These are the most common types of gears used in FTC. The teeth are parallel to the axis of rotation. Spur gears can only be used on parallel shafts.

| | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------- | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------- | |

Helical Gear

Teeth are twisted obliquely to the gear axis.

| | | | | | | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- | |

Bevel Gear

One of a pair of gears used to connect two shafts whose axes intersect, and the pitch surfaces are cones. Teeth are cut along the pitch cone.

*19823 Jolly Blue's Differential Swerve drive*

| | | | | -------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------- | |

Miter Gear

A special class of bevel gear where the shafts intersect at 90° and the gear ratio is 1:1.

| | {% endtab %} | | {% tab title="Uncommon Gears in FTC" %} | | | | ---------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | |

Rack

The rack is a bar containing teeth on one face for meshing with a gear.

| ![](https://lh7-rt.googleusercontent.com/docsz/AD_4nXdZh4ailAFDYq6o4AecoeOsnE7zJOzeOm9nNDQfuzQTUZJ8n3GmVMOLok9e4jGWTZ2mdeTREKq4sM88f1hJWQ3mWjck8uwxxogAeouuOszqXiKDM4PdvGEKeZ6Sw4qNJaw5glgAYA?key=l78xoyVWhVq4XRDwJujbd3mS) | | | | | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | |

Internal Gear

An annular gear has teeth on the inner surface of its rim.

The internal gear always meshes with the external gear.

| ![](https://lh7-rt.googleusercontent.com/docsz/AD_4nXcNNgQXehJVOxyPny1bp3H-sjU8eKvBBTnaqmhcf-05w93Gi7JzFguknJ0Fr-v5OYK7vtnoPKNf5nyRBNNoRSDldAjZBW2bq0LxdpSWQOSAYecBbWStJpKoOryoLrGGkEGfMrGW?key=l78xoyVWhVq4XRDwJujbd3mS) | | | | | ---------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | |

Screw Gear

A helical gear that transmits power from one shaft to another, non-parallel,

non-intersecting shafts.

| ![](https://lh7-rt.googleusercontent.com/docsz/AD_4nXd1asq1Rksy7kM9IMSDIjaoyjPvlSDL3ad2q-tqVyvpvw82Z4pkJTnNZ8fKYXFFXaFjOFdOV1yxss74sl9DR499TeyD-SI5a_brIbNABVRb8Sep8NY5yp74mXE72l6XBm_0YVBrdg?key=l78xoyVWhVq4XRDwJujbd3mS) | | | | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | |

Worm Gear

The worm is a shank having at least one complete tooth (thread) around the pitch surface; the driver of a worm wheel. A worm wheel is a gear with teeth cut on an angle to be driven by a worm.

| ![](https://lh7-rt.googleusercontent.com/docsz/AD_4nXd3LSBqKoxr4O66tzu_IQXdWhtVjwtD7STT86yZWxcnbMBeWi6crlw-Hqvr6NeHFujNvqfm35t-dkh3tan7X80Zen2ahSuE6BJg6J0pezpec6HCt7kWTteCn-UURuV4zSQb2ITghQ?key=l78xoyVWhVq4XRDwJujbd3mS) | {% endtab %} {% endtabs %} # Gear Ratios A gear ratio is the relationship between the sizes of two gears. If a smaller driving gear turns a larger driven gear, the larger gear rotates more slowly but with greater torque. For example, if a driving gear has 10 teeth and the driven gear has 20 teeth, the ratio is 2:1, meaning the smaller gear must complete two full rotations for the larger gear to rotate once.

*A diagram of a 2:1 Gear ratio by* *Bartosz Ciechanowski*

Gear ratios in *FIRST* Tech Challenge are crucial for optimizing speed and torque, depending on the task at hand.

Increasing Speed

If you use a higher gear ratio (2:1, for example), the output gear spins faster than the input gear, while lowering torque. This is particularly useful for applications such as active intake, flywheel, or turret systems.

Increasing Torque

A lower gear ratio (1:2, for example) means the output gear rotates more slowly but with greater force. This is ideal for lifting mechanisms, drivetrains, or linear extension.

To optimize efficiency, ensure that torque and speed are balanced; having excess torque on a wrist joint could mean wasted force, so gearing it up for extra speed can improve movement while maintaining control. Always match the gear ratio to the actual load and motion requirements to avoid inefficiencies that drain power or limit performance. # Wheels # Linear Extension # Motors Motors convert electrical power into rotating mechanical energy. There are multiple types of motors, including brushed, brushless, and stepper motors. Most active mechanisms on FTC robots use motors to provide motion. ### Motor Selection Choosing the right motor for your application requires understanding the balance between **speed**, **torque**, **power output**, and **gear reduction**. There’s no one-size-fits-all motor—each use case demands careful matching of motor characteristics to the mechanical load. #### Gearboxes: Amplifying Torque or Speed Most FTC motors come with **pre-installed gearboxes** that affect output in two key ways: * **High gear ratio = Low speed, High torque** * **Low gear ratio = High speed, Low torque** For example: * A motor with a **19.2:1 gearbox** will turn slowly but provide strong torque—great for lifting heavy arms or driving slides. * A motor with a **5.2:1 gearbox** spins faster with less torque—better for wheels or shooters. {% hint style="info" %} *Tip: Check the stall torque and free speed in the motor datasheet before deciding.* {% endhint %}

### How to Calculate Torque and Speed Motor **power output** is a measure of how much work the motor can do per unit time, and is defined as: ```markdown Calculating Motor Power, Torque, and Gear Reduction Given: - Voltage: 12V - Current: 9A - Free Speed: 6000 RPM - Efficiency: ~75% 1. Input Power Electrical power = V × I = 12V × 9A = 108W Mechanical output = 108W × 0.75 = 81W 2. Free Speed Torque Convert RPM to rad/s: 6000 RPM × 2π / 60 = 628.3 rad/s Use: P = τ × ω So: τ = P / ω = 81 / 628.3 ≈ 0.129 Nm 3. Gearbox Effect (Example: 20:1 reduction) - Speed: 6000 / 20 = 300 RPM = 31.42 rad/s - Torque: 0.129 × 20 = 2.58 Nm - Power stays the same: 2.58 × 31.42 ≈ 81W Gearing doesn't create power—it **trades** speed for torque (or vice versa). Use gear ratios to match motor output to what your mechanism actually needs. ``` {% hint style="danger" %} ## COMING SOON: Motor Power Calculator {% endhint %} ### Torque vs Speed Every motor has a **performance curve**. At one end is **maximum torque at zero speed** (stall torque), and at the other is **maximum speed at zero torque** (free speed). In between is the **power peak**—the point where the motor is doing the most work. When designing a mechanism: * **Too much torque = Slow and inefficient** * **Too much speed = Can’t move the load** The **ideal balance** happens when you operate near the motor's peak power, which is around **50% of its stall torque** and **50% of its free speed**.

| Mechanism Type | Needs More... | Gearbox Recommendation | | -------------- | ------------- | -------------------------------- | | Arm or Lift | Torque | High ratio (e.g., 19.2:1, 26:1) | | Flywheel | Speed | Low ratio (e.g., 5.2:1) | | Drivetrain | Balanced | Mid ratio (e.g., 13.7:1 or 20:1) | {% hint style="info" %} *Rule of Thumb:* If a motor is getting hot or stalling, you probably need more gear reduction. If it’s spinning super fast but not moving anything, increase the load or reduce gear reduction. {% endhint %}
# Servos Servos are essentially small motors that can only rotate a set number of degrees via a 3-wire PWM connector. Servos are used in FTC for high-precision applications that are low-load. Typically, servos have limited range of rotation (180°-270° is common). The output has splines, which are the rigid teeth that are on top of the servo. ## Dual Mode Dual Mode servos are servos that allow users to switch between two operational modes: Servo mode and continuous mode.

Servo Mode

Servos that can rotate to a given position based on a PWM (Pulse Width Modulation) input signal are called regular servos.

Continuous Mode

Continuous rotation servos are effectively just small motors in a servo form factor. They have no position control; instead, a PWM signal is used to control their rotation speed.

# Servo Selection Servos generally fall into two categories: torque-focused or speed-focused. Torque servos prioritize force, allowing robots to handle heavier loads and maintain strong positioning, while speed servos focus on quick, responsive movement, ideal for applications requiring fast adjustments. In FIRST Tech Challenge, the three commonly used servo brands are REV, GoBILDA, and Axon. {% tabs fullWidth="true" %} {% tab title="REV Servo (Cose-effective Option)" %} REV offers one servo, the Smart robot servo, a good price-to-performance servo. It features a dual mode, offers average output torque and speed, and has a brass gearbox.


	Smart Robot Servo
Speed at 6 Volts	≈71 RPM
Torque at 6 Volts	13.5 kg·cm
Range of Rotation	270°
Price	$30.00

{% endtab %} {% tab title="GoBILDA Servos (Balanced Option)" %} GoBilda servos are a good price-to-performance servo. They feature a dual mode, and offer higher than average output torque or output speed (depending on the gearbox), and a steel gearbox.


	Torque Servo	Speed Servo	Super Speed Servo
Speed at 4.8 Volts	40 RPM	90 RPM	180 RPM
Torque at 4.8 Volts	17.2 kg·cm	7.9 kg·cm	4 kg·cm
Range of Rotation	300°	300°	300°
Price	$36.99	$36.99	$36.99

{% endtab %} {% tab title="Axon Servos (Premium Option)" %} Axon servos are the best price-to-performance high-performance servos. They have a high efficiency and a high power output. In addition, these servos can track their absolute position via an analog output wire.


	MICRO+	MINI+	MAX+
Speed at 4.8 Volts	≈118 RPM	≈91 RPM	≈71 RPM
Torque at 4.8 Volts	6.5 kg·cm	20 kg·cm	28 kg·cm
Range of Rotation	255°	255°	255°
Price	$69.99	$86.99	$89.99

{% endtab %} {% endtabs %} # Introduction to Mechanisms This section is still under construction! If you have any recommendations for what you want to see, feel free to reach out, at # How to Chassis # Frame Construction # Mecanum # Tank Drive # Swerve Drive # Linear Slides # Rigging # Counter Springing # Telescoping Pole # Linear Rails # Lead Screw Actuators # Rack and Pinion # Page 5 # Page 6 # Page 7 # Intro to CAD Course This course is designed to take you from a complete beginner to confidently modeling a full FTC robot. It emphasizes FTC-specific features and tools through engaging proLing concepts. As you advance, the projects become progressively more independent, yet always provide references to guide you along the way. {% stepper %} {% step %} ### Level 1 * **CAD Fundamentals** – An introduction to the basics of computer-aided design * **Onshape Setup** – Step-by-step guidance on creating an account and adding essential tools * **Navigation Guide** – How to efficiently move through Onshape’s interface and features * **Core Principles** – Fundamental concepts that foster a strong design mindset

{% endstep %} {% step %} ### Level 2 * **CAD Essentials** – Master the basics of sketching, part design, multi-part modeling, and assemblies with Onshape Learning Courses and FTC-focused exercises * **Mechanical Systems** – Explore power transmission principles and develop gearbox models * **Top-Down Workflow** – Begin applying top-down design strategies for FTC projects

*Exercise #6 Belt and Gear Transmission*

{% endstep %} {% endstepper %} # What is CAD? CAD, or "Computer-Aided Design," is a powerful software tool utilized across industries by engineers, manufacturers, architects, and designers to transform ideas into reality. It enables the creation of 3D models using various techniques and tools, aiding in prototyping, manufacturing, and product development. CAD files can be sent to machines for printing or material cutting, and detailed drawings can be produced to support manual machining and assembly. For this guide and website, we use Onshape as our CAD platform, but there are many [different types of CAD software](/intro-to-cad/level-1/what-is-cad/different-types-of-cad-software).

## Why use CAD? With CAD, you can design more advanced custom components and mechanisms. CAD also allows teams to iterate ideas before prototyping and manufacturing, and it helps cut down on prototyping time. Good CAD efficiency can help a team design a good robot early on in the season, leaving more room for software testing and driving practice. 1. Using CAD to design your robot ensures that all components fit together seamlessly. 2. With CAD, you can accurately measure your robot's dimensions, making sure it meets the size requirement. 3. CAD serves as both a digital blueprint of your robot and as a bill of materials, helping you during the ordering process by specifying exactly what parts you need. 4. CAD skills are highly valuable in various industries and can enhance your resume. Learning CAD with any software builds a strong foundation, making it easier to adapt to other CAD platforms in the future. # Different types of CAD software There are many CAD software options available, each with unique features suited for different industries and applications. In the context of FTC robotics, teams commonly use Onshape, Fusion 360, and SolidWorks due to their accessibility and functionality.

Onshape is a cloud-based CAD software that makes it easy for teams to design and collaborate. It has great tutorials for beginners and a file management system that keeps everything organized. While it may not have every advanced feature found in other CAD programs, it has everything FTC teams need to build and refine their robots, and it's constantly improving with regular updates. One of its biggest strengths is real-time collaboration, allowing multiple teammates to work on the same design from anywhere, as long as they have an internet connection. Since it doesn’t require a high-end computer, many FTC teams have switched to Onshape for its flexibility and accessibility.

Autodesk Fusion 360 is a popular choice among hobbyists and combat robotics enthusiasts, largely because it's free for these users. This widespread adoption has led to an abundance of high-quality tutorials, making it easy to learn. It also features cloud saving, helping prevent data loss and ensuring seamless access across devices. A standout advantage of Fusion 360 is its native compatibility with macOS, unlike many other CAD programs. However, it doesn’t handle large assemblies, which may be a consideration for complex designs.

SolidWorks is a powerful, industry-standard CAD software widely used in engineering and product design. It offers robust 3D modeling tools, simulation capabilities, and manufacturing integration, making it ideal for professional workflows. Unlike cloud-based CAD programs, SolidWorks runs on Windows and requires a capable computer, but its precision and extensive feature set make it a go-to choice for teams working on complex assemblies. While it lacks built-in real-time collaboration, it integrates with data management tools to streamline teamwork. Many FTC teams use SolidWorks for its advanced modeling capabilities, especially when designing intricate mechanisms and optimizing parts for manufacturing.

# Onshape setup In this section, we'll guide you through the process of registering for Onshape and downloading essential resources for using CAD in FTC robotics. ### Registering for Onshape Onshape provides a free education license for students, giving access to powerful CAD tools for free. The education plan is highly recommended, as it allows users to create private documents and unlocks additional useful features. To start registering, go to the [Onshape for Education](https://onshape.com/education-plan) page and select "Create a Student Account" on the top left of the page. {% stepper %} {% step %} ### Put in your Information

{% endstep %} {% step %} ### Select a Student in Grade School

{% endstep %} {% step %} ### Put in your School's Information

{% endstep %} {% endstepper %} Onshape will then proceed to check your information, which will take some time, then send a verification email to activate your account. You'll be asked to set a password, then you'll enter your dashboard. # FTC Insert Tool ## Setting up the FTC Insert Tool FTC Insert Tool is an Onshape plugin that contains a large library of parts that are often useful in FTC. To install it, go to the [FTC Insert Tool App](https://cad.onshape.com/appstore/apps/Design%20&%20Documentation/6515cfb91574253b1b96a6ba) in the Onshape Appstore. Press "Subscribe", then "Get for Free". This will automatically add the FTC Insert Tool to your Onshape account. After subscribing, the FTC Insert Tool inserter won't show up in already open documents until you reload. This is a first-time thing, though. {% embed url="" %} # Featurescripts FeatureScripts are user-created custom features designed to simplify and enhance the FTC design process. #### How To Install Featurescripts 1. Open any Onshape document and go to a Part Studio. 2. Click the button on the toolbar labeled "Add custom features." 1. If you've previously added any FeatureScripts, one of those may appear instead. In that case, click the dropdown and select the Add button. 3. Paste the link of the OnShape document with the featurescript in it into the search bar 4. Select the featurescripts you want to add to your profile, then exit the box. They will then be accessible in all documents from the same drop-down in the toolbar where you added the feature. ## List of Featurescripts ### Pulley Gen This isn't a featurescript, but it is still very useful when creating pulleys. {% embed url="" %} To use this, you must first copy the document, then go to an assembly and go to: Insert -> Other Documents -> Created By Me. It should be listed there as Pulley Gen - Copy. ### Belt and Chain gen This is used to create highly customizable belts and chains. Pulley/sprocket tooth count is automatically calculated from sketch pitch diameter. {% embed url="" %} ### Part Lighten This is better than Onshape's "Lighten" or "Vent" features, with more control over ribs, cut depth, fillets, etc. It can also give you an estimate on how much weight is being saved. {% embed url="" %} # CAD Theory CAD is a digital design tool used to create parts before manufacturing them. While our documentation primarily covers FTC-specific CAD practices, understanding the foundational concepts is essential for getting started with Onshape. ## Starting with a Sketch If you wanted to create a cube in Onshape, you would start by representing its profile in a 2D sketch. So, what would the sketch look like for a cube? If you take the section from the plane on top of the cube, which is called the “Top" plane in Onshape, you can see that this sketch is simply a square.

## Transitioning from Sketch to 3D **Creating a Solid Shape** When working in a sketch, you define the fundamental properties of a shape—its position and dimensions. For example, a circle’s location and diameter are determined within the sketching environment. Once you bring this sketch into 3D, these characteristics carry over, establishing the final placement and size of the cylindrical feature in the Part Studio. To ensure consistency and accuracy, it's crucial to fully define sketches. Otherwise, parts may end up with unintended dimensions or placements.

A circle's location and diameter shown in a sketch

The extruded circle having the same location and diameter

**Extruding to Build Volume** To turn a sketch into a three-dimensional object, you use features. One of the most common ways to do this is with the **extrude** function, which extends a sketch profile into 3D space. Similar to how you define a sketch, an extrude requires specific parameters. For instance, you must set a **depth** (or final height) to determine how far the shape extends. Adjusting these settings allows you to create precise geometry tailored to your design needs.

Extruding a hexagon with a depth of 40mm

Revolving around a complex shape to create a candlestick

**Alternative Approaches** Instead of extruding, you can use the revolve feature to create certain shapes, such as a candlestick. This method involves rotating a sketch profile around a central axis, forming a continuous shape. Different modeling techniques exist, and the choice depends on the design intent—whether prioritizing manufacturability, editability, or structural integrity. Every 3D modeling approach has trade-offs, but understanding how features like extrude and revolve work helps you build designs efficiently and with greater control.\ Let me know if you want this adjusted further! # A. Onshape Basics (WIP) ## Introduction Level 2 begins here! In this phase, you'll dive into a series of Onshape exercises and projects designed to strengthen your CAD skills within an FTC environment. Level 2A is divided into three main sections: * **Sketching and Part Design** * **Multi-Part Part Studios** * **Assemblies** Each section provides a learning course to build your skills, followed by an exercise to apply them directly in an FTC context. ## Learning Courses [Onshape's Learning Center](https://learn.onshape.com/) offers free courses and articles covering everything from basic document navigation and sketching to advanced surface and sheet metal modeling. It's a great resource for both beginners and experienced users.

While we use a few selected courses to build foundational CAD skills in Onshape, the majority of the curriculum is project-based. Each course includes short videos and practice models, with an expected completion time of 2–4 hours. # Sketching and Part Design Sketches and features are the building blocks you will use to create every 3D model in Onshape, so it's good to have a good grasp on the fundamentals. ## Learning Center Courses Work through the following Onshape Learning Courses: {% stepper %} {% step %} ### Introduction to Sketching Covers various sketch tools, constraints, and best practices for an efficient sketching workflow. {% endstep %} {% step %} ### Introduction to Part Studios Guides you through creating parts using a range of features. {% endstep %} {% endstepper %} Mastering these fundamentals will allow you to create almost any part you need. The next exercises focus on incorporating design intent into your workflow and learning how to structure a complete project with multiple components. # Exercise #4 Simple Gearbox ### Practice Exercises Get ready to practice! Begin by copying the Stage 2B Exercises Document using the button below, just as you did with the Stage 2A Exercises Document. Each exercise is organized into a folder and includes a **"reference" tab**—a preview of the final model—as well as one or two tabs for completing the exercise. {% hint style="info" %} [**COPY THIS DOCUMENT**](https://cad.onshape.com/documents/590c0f6b2a80e0dca120c280/w/f3da0f6ce53211134a745ecb/e/f1734caa16f56215c1e2e04f?renderMode=0\&uiState=6849b55e83d04e65c31e0516) {% endhint %} ### Exercise 4: Simple Gearbox In this exercise, you'll be CADing and assembling a **single-stage gearbox**. The aim is to introduce the basics of designing a simple gear transmission. Along the way, you'll also get hands-on experience with [gears](/transmitting-power/gears), [motors](/transmitting-power/motors), [bearings](/transmitting-power/introduction-to-motion/bearings), c2c, [gear relation](/transmitting-power/gears/gear-ratios), and the [FTC Insert Tool](/intro-to-cad/onshape-setup/ftc-insert-tool). #### Layout Sketches A **layout sketch** captures the fundamental geometry of a design without locking in precise details. By keeping key dimensions flexible, layout sketches facilitate easy adjustments as the design evolves. Moving forward, we'll rely on layout sketches for nearly all designs. {% tabs %} {% tab title="Part Studio Instructions" %} **Navigate to the "Exercise #4 Simple Gearbox" part studio tab** in the copied document and follow the instructions to complete the part studio. {% stepper %} {% step %} ### Create a Layout Sketch for the Gearbox

Draw pitch diameter circles for the 60-tooth and 20-tooth gears. Make them tangent to define the center-to-center distance between the gears. Then, constrain the gear centers so they align vertically. {% endstep %} {% step %} ### Create a new sketch for the motor plate.

Using the layout as the reference, draw an 8mm hole for the bearing and a 14mm hole for the axle that sticks out from the motor. Note that depending on your manufacturing processes and tolerances, you may need to draw your bearing holes slightly larger or smaller. Add four mounting holes for the motor and four bolt holes for connecting the two plates using center point rectangles. The circular pattern can also be used to duplicate the circles around the square. Make sure that these rectangles are using construction lines, so it doesn't interfere when we extrude (press q on lines to turn them into construction lines). {% endstep %} {% step %} ### Finishing Bottom Plate

Using center point rectangles, sketch fillets, and 3-point arcs, outline the plate around the holes and the motor outline. Extrude the motor plate to be 4mm thick. {% endstep %} {% step %} ### Creating Spacers

Create spacers by making the inner diameter 4mm and making the outer diameter the same as the sketch fillet. Then, extrude the spacer by 7mm. {% endstep %} {% step %} ### Creating Top Plate

By using the Use tool (the cube), you can copy the geometry and holes of the motor plate. Then add a 20mm diameter circle, a line connecting both of the top mounting holes to the circle, and sketch fillets. Then extrude by 4mm, and fillet the edges of the semi-circle by 5mm. {% endstep %} {% step %} ### Countersinking Screw Mounts

Now create holes for the screws by making circle with a diameter 8mm, extruding them by 2mm, and fillet them by 0.5mm. {% endstep %} {% step %} ### Creating a Gear

You can create a gear by looking up "Spur Gear" in the "Search tools" search bar. Make the gear have 60 teeth, make it 5mm deep, and make its module 0.8. You can also hide the top plate for a better view of the gear. {% hint style="info" %} All GoBILDA gears have a module of 0.8mm {% endhint %} Then create the center REX bore by using the circumscribed polygon tool and making a 6-sided shape with a diameter of 8mm. {% endstep %} {% step %} ### Finished Part Studio

Now the part studio is finished, and you can move on to the [assembly](/intro-to-cad/level-2/a.-onshape-basics-wip/exercise-4-simple-gearbox#assembly-instructions). {% endstep %} {% endstepper %} {% endtab %} {% tab title="Assembly Instructions" %} **Navigate to the "Exercise #4 Simple Gearbox" assembly tab** in the copied document and follow the instructions to complete the assembly studio. {% stepper %} {% step %} ### Starting the assembly

Import the top and bottom plates as well as the spacer. Mate the spacer to the bottom plate, and use the "replicate" tool to copy the spacers. Then mate the top plate to the spacers. {% endstep %} {% step %} ### Import Parts using the FTC Insert Tool

Insert the Bearings and the axle from the FTC Insert tool, as well as the gear from the part studio. Then, mate the bearing to the bottom plate, and mate the gear to the rotating part of the bearing. Mate the other bearing to the top plate and then mate it to one of the spacers. {% endstep %} {% step %} ### Import the remaining Parts

Import the rest of the parts, and mate the 20-tooth gear onto the rotating shaft. Then mate the screws and use the replicate tool to replicate the screw mates. {% endstep %} {% step %} ### Gear Relation

Create a gear relation by choosing the two revolute mates that are mated to your gears. You can do this by clicking on the motor and the bearing dropdowns and going to mates, where you click the revolute mate. Now, calculate the [gear ratio](/transmitting-power/gears/gear-ratios) and reverse the direction. {% endstep %} {% endstepper %} {% endtab %} {% endtabs %} # Exercise #5 Two-Stage Gearbox ### Exercise 5: Two-Stage Gearbox In this exercise, you'll be CADing and assembling a **two-stage gearbox**. The goal is to build experience with more advanced gearbox designs. Additionally, you'll learn how to use the[ **Part Lighten Featurescript**](/intro-to-cad/featurescripts#part-lighten) to optimize and reduce weight in your components. {% tabs %} {% tab title="Part Studio Instructions" %} **Navigate to the "Exercise #5 Two-Stage Gearbox" tab** in the copied document and follow the instructions to complete the part studio. {% stepper %} {% step %} ### Create a Layout Sketch

Draw pitch diameter circles for the 60-tooth and 20-tooth gears. Make them tangent to define the center-to-center distance between the gears. Then, constrain the gear centers so they align vertically and horizontally. {% endstep %} {% step %} ### Create a new sketch for the motor plate.

Using the layout as the reference, draw 14mm holes for the bearings. Note that depending on your manufacturing processes and tolerances, you may need to draw your bearing holes slightly larger or smaller. Add four mounting holes for connecting the motor plates, and begin adding circles to create the geometry of the plate. {% endstep %} {% step %} ### Finishing Top Plate

Using center lines, sketch fillets, 3-point arcs, and the mirror tool, finish sketching the geometry of the top plate. Extrude the motor plate to be 4mm thick. {% endstep %} {% step %} ### Creating Spacers

Create spacers by making the inner diameter 4mm and making the outer diameter the same as the sketch fillet. Then, extrude the spacer by 12 mm. {% endstep %} {% step %} ### Creating Bottom Plate

By using the "Use" tool (the cube), you can copy the geometry and holes of the top motor plate. Then add a 16x16mm center point rectangle for the motor mount and mirror it to the other side. Then, extrude by 4mm. {% endstep %} {% step %} ### Countersinking Screw Mounts

Now create holes for the screws by making circle with a diameter 8mm, extruding them by 2mm, and fillet them by 0.5mm. {% endstep %} {% step %} ### Creating the gears

Make the gear have 60 teeth, make it 5mm deep, and make its module 0.8. You can also hide the top plate for a better view of the gear. Make a second gear with 20 teeth, and 5mm deep, and make its module 0.8 as well. {% endstep %} {% step %} ### Pocketing the Top Plate

In order to pocket the plates, make sure to make a new sketch and create rib lines. Now use the "Part Lighten" Feature Scripts and click on the top plate and the new sketch you created for the rib lines. {% endstep %} {% step %} ### Pocket Bottom Plate

To pocket the other plate, click the face of the bottom plate, and use the same rip line sketch for the bottom plate's rib lines. {% endstep %} {% step %} ### Gear Spacer and Finished Part Studio

Create a new sketch, draw a 10mm circle, and using the circumscribed polygon tool and make a 6-sided shape with a diameter of 8mm. Extrude by 5mm, and you can start the [assembly](/intro-to-cad/level-2/a.-onshape-basics-wip/exercise-5-two-stage-gearbox#assembly-instructions). {% endstep %} {% endstepper %} {% endtab %} {% tab title="Assembly Instructions" %} **Navigate to the "Exercise #5 Two-Stage Gearbox" assembly tab** in the copied document and follow the instructions to complete the assembly studio. {% stepper %} {% step %} ### Starting the assembly

Import the top plates, bottom plates, spacer, and the gears. Mate the spacer to the bottom plate, and use the "replicate" tool to copy the spacers. Then mate the top plate to the spacers. {% endstep %} {% step %} ### Import Parts using the FTC Insert Tool

Import the bearings, an 8mm standoff, and a 58mm axle. Once mated to the bottom plate, add the gears, the gear spacer, and the final bearings. {% endstep %} {% step %} ### Import the remaining Parts

Import the rest of the parts, and mate the 20-tooth gears onto the rotating shaft. Then mate the screws and use the replicate tool to replicate the screw mates. Don't forget to add screws to the standoff to hold it in place. {% endstep %} {% step %} ### Gear Relation

Now, create 3 different gear relations by choosing the two revolute mates that are mated to your gears. You can do this by clicking on the motor and the bearing dropdowns and going to mates, where you click the revolute mate. Now, calculate the [gear ratio](https://www.ftcwiki.org/transmitting-power/gears/gear-ratios) and reverse the direction. {% endstep %} {% endstepper %} {% endtab %} {% endtabs %} # Exercise #6 Belt and Gear Transmission ### Exercise 6: Belt and Gear Transmission In this exercise, you'll be CADing and assembling a **belt and gear transmission**. The goal is to further refine your modeling skills. Additionally, you'll learn how to use the [**Belt and Chain Gen Featurescript**](/intro-to-cad/featurescripts#belt-and-chain-gen) as well as the[ Pully gen Document](/intro-to-cad/featurescripts#pulley-gen). #### Part Studio Instructions **Navigate to the "Exercise #5 Two-Stage Gearbox" tab** in the copied document and follow the instructions to complete the part studio. #### Assembly Instructions **Navigate to the "Exercise #5 Two-Stage Gearbox" assembly tab** in the copied document and follow the instructions to complete the assembly studio. WIP # B. Power Transmission (WIP) ## Introduction Up to this point, the models you've built have been structural components—but that's just one part of a robot. To make a robot move and perform tasks, motors that generate rotational motion are essential. In Level 2B, you'll start working with basic power transmissions, which include motors, bearings, shafts, gears, belts, and chains—all used to convert rotational motion into functional movement. This stage focuses on the fundamentals of power transmissions, with a special emphasis on modeling them in CAD. Motor selection and power transmission ratio calculations will be covered later in Stage 2, where you'll explore multiple different mechanisms in greater detail. In this stage, there are exercises designed to practice modeling simple power transmissions in the form of stand-alone gearboxes. I
## Examples Take a look below at some examples of different types of power transmissions found in robots.

*FTC 16197 SWARM's PTO for Ultimate Goal*

# C. Practice Mechanisms (in Progress) # Introduction # Exercise #7 Flywheel Shooter # Exercise #8 One Servo Claw # Exercise #9 Roller Intake # D. Linkages (in Progress)