3D printing is one of the most common advanced manufacturing technique that is used in VexU allowing teams to make complex parts to suit use cases. This technology allows for rapid prototyping, giving competitors the flexibility to iterate on designs quickly and affordably. Not only does this enhance the capability to fine-tune robots for optimal performance, but it also allows for low cost manufacturing.
Perimeters are the outermost layers of a 3D printed object, providing the shape and are crucial for the object's strength. Increasing the number of perimeters enhances the part's durability and impact resistance.
A minimum of 3 perimeters is recommended for any piece that will be under continuous strain or experience impact.
Infill refers to the internal structure that occupies the space inside a 3D printed object. It adds strength and rigidity while minimizing material usage and print time. The infill percentage and pattern can be adjusted depending on the application.
20% infill is a safe bet. Gyroid & 3D honeycomb are the most common patterns.
Polylactic Acid (PLA) is by far the most common 3d printing filament due to its ease of use, low printing temperature, and above average durability/strength. PLA is a versatile material that can be used for the majority of parts on a robot from structure, to motion components.
Acrylonitrile Butadiene Styrene (ABS) is one of the strongest and most durable 3d printing filaments, but is more difficult to work with. ABS has a high impact resistance and is well suited for any portion of a robot that will undergo repeated stressing such as gears.
Polyethylene Terephthalate Glycol (PETG) is seen as a middleground between PLA and ABS. PETG is more durable than PLA, but far easier to work with than ABS.
These are based on the experience & practice of the Purdue SIGBots.
Screw THROUGH Holes - 0.175" Diameter
Screw SELF-TAP Holes - 0.160" Diameter
Laser cutting is an ideal manufacturing technique in VexU for any flat design such as gears, brackets, and more. The technique is fast, and versatile across materials allowing for quick iterations and final products that suit the designers' needs.
The process begins by designing a digital program in a CAD/CAM system that directs the laser cutter. This design file, typically a DXF or DWG file, outlines the desired shapes and dimensions of the parts to. The laser cutter, guided by the CNC system, then uses a concentrated beam of light to melt, burn, or vaporize the material along the programmed path.
SAFETY FIRST! Lasers are dangerous tools that can cause serious harm if not used properly. Make sure that proper PPE is used, there is supervision, and the machine is setup with proper ventilation.
Laser Cutting is very versatile, but many people lack experience with the technique and therefore fall into common traps. Firstly, avoid sharp corners (both internal & external) that would likely be rounded over when being cut. Additionally, plan joining features early for each part so they can be cut properly & reduce assembly time.
Until tolerances are refined, and experience is had, make sure to test parts & features on less expensive, easier to obtain/cut materials as to not waste time and money.
Polycarbonate - This material is strong, impact-resistant, and readily accessible in most areas. One concern with Polycarbonate is its flexibility, especially since most laser cutting machines will only cut <0.25" thick Polycarbonate.
Delrin - This material has a high stiffness, low friction, good dimensional stability and is great for applications such as gears because of this. Delrin is more expensive than some more common plastics, but is still readily available on sites like Amazon.
Aluminum - Despite needing a powerful laser to accomplish, Aluminum can be cut on a laser cutting machine making it perfect for complex structures & strong braces. Aluminum itself is lightweight, strong, and corrosion-resistant making it a great material for use in competitive robotics.
This is a Work In Progress. We would love feedback & assistance with this from teams with experience.
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This has been used in sets of tracker wheels for odometry. There is some changes to the cable that is needed to connect it to the V5 brain through the 3-wire ADI ports.
This has been used in a set of tracker wheels for odometry. It used M3 screws to attach.
To export parts from OnShape, right click on the desired part, and select 'Export'. To export the entire assembly, click the 'Export Tab' button from the bottom toolbar.
This part was originally designed in 4 parts for a chassis, but then began being used for tracker wheels. There is an updated tracker wheel version with a specific insert below.
These were designed to use the with a set of additional 3D printed brackets to mount the AMT-102v encoder & house everything together. This also uses .
