Plastic Antweights
Plastic Antweights
In 2015 Western Allied Robotics introduced a new robot class called Plastic Antweights. The robot class has gained popularitity and the rules set has been adopted by SPARC.
The spirit of the Plastic Antweight classe is to have an easy entry point for new builders, and to encourage creative designs by limiting materials to easy-to-work-with plastics that are commonly used in 3D printers, which don’t have strength characteristics common in the standard classes. These limitations not only make the class easy to build for, but have encouraged a lot of creative designs which may not have been tried in the full-combat 1lb antweight class.
It is important to note that plenty of non-plastic materials can be used in parts of the robot class. Foam is allowed for wheels and internal shock absorption. Metal fasteners can be used as long as they don't act as armor or weapon impactors.
The 3D Printing page lists numerous bot designs on Thingiverse that can be printed, but most events do not require the robots to be printed.
Allowed Plastics
PLA
PLA is inexpensive, but brittle.[1] It is the most common 3D printing filament. It rarely warps in use and is great for tiny parts.[2] It's a great starter material, and recommended for printing prototype parts. Many builders prefer other plastics, especially for their active weapons or armor. Pure PLA is made from cornstarch[3] and gives off a corn syrup odor which reminds some people of waffles.
PLA+
Various manufacturers offer "PLA+" and/or "Tough PLA," which are modified PLA filaments that are meant to be less brittle. With an acrylic additive, for instance, it may show much better impact resistance.[4] Inland and eSun claim their PLA+ products are 10x stronger than regular PLA.
PET
PET (Polyethylene terephthalate) is somewhat brittle so it isn't the best choice for robot parts that are likely to receive damage but it is very ridgid and can be useful for parts where rigidity is key.
PETG
PETG (a copolyester) is more heat resistant, more flexible, and less brittle than PLA.[5] It is well suited for 3D printing mechanical parts. Since it is more likely to flex under impact its resilience may be useful to the bot builder, but it is 2-3% heavier than PLA. Observe manufacturer's recommendations when printing, as it tends to stick very strongly to smooth print beds. You'll notice a fairly mild hot-plastic odor when printing.
ABS
ABS is a strong and reasonably impact-resistant material at a moderate price, but warps easily and smells worse while printing. Its low density makes it one of the lightest of all printable plastics (PLA is about 20% heavier for the exact same print). You'll probably need to print it in an enclosure for best results; this keeps its temperature even during printing, so that it only shrinks after printing instead of curling or warping during printing. Many hobbyists ventilate the enclosure to the outdoors with fan(s) due to the odor.
OTHER
Individual events can allow other plastics that meet the intent of the rules. If you are really itching to use another kind of plastic like HIPS, contact your event organizer and see what they say. If you want to use a durable or high performance plastic like nylon, you should just build for the open-ant class.