NameThatPart

Knowing the names of things is part of the challenge; it's difficult to do internet searches if you don't know the name of the thing you're looking for, even harder if you don't know it even exists. This page names some things useful for building robots, so you can get a start on learning or research.

Materials

Plastics

• Polycarbonate (trade names Lexan™, Makrolon™): Strong material which can be optically clear; used for the windows of combat arenas and as armor on robots. It is also a 3D printing material or additive. Also used in the making of bulletproof windows and barriers. Often mistaken for acrylic (Perspex, Plexiglass), but acrylic is easily cracked and not suitable for combat robots.

• PLA: A thermoplastic often used in 3D printing. It is moderately strong but its ease of use makes it a popular choice.

• ABS: Also a common plastic used in 3D printing. It is stronger than PLA but can be more difficult to work with, and offers no advantages compared to PLA except slightly lighter weight.

• PA, or Nylon: Frequently milled or 3D printed to make strong, flexible robot combat chassis and components.

• POM (Delrin, Celcon, acetal): This low friction high durability plastic can be used instead of aluminum in some cases. Its much lighter but not as strong.

• HDPE & UHMW: These high strength plastics are often used as armor. They tend to deform and bend instead of cracking or completely failing.

• EVA Foam: A lightweight foam useful for things like wheels that will take damage. Could also be used for internal padding. Available in sheets of various thickness or cylindrical dowel stock.

Composites

• FR4 / [[1] G10]: This material goes by several names including GRP (Glass reinforced polymer), FRP (fiber reinforced plastic), G-10, and Garolite. It's made of resin reinforced by glass fibers. G10 is available in sheets, rods, corner angles, etc.[2] According to ULS, this material can be laser cut with a CO₂ laser.[3] FR4 is also flame retardant, and is a common material for circuit boards.[4]
  • G10 has very high strength compared to unreinforced plastics, and is resistant to abrasion and cracking. In combat robotics it can be used as lightweight armor[5] or structural members in insect weight classes. It's an insulator, and won't short out electronics even if opponents attack and shred it.
  • Safety: Use appropriate protective gear to avoid inhaling glass fibers when cutting or handling this material.

• CFRP: Carbon-fiber reinforced polymers are extremely strong and light. Flat carbon-fiber panels are common for weight savings in insectweight classes. It's also possible to buy professional 3D printing filament with continuous fiber, and there are many chopped carbon fiber filaments on the market. However, flat sheets and panels are far stronger and as a result are commonly used.
  • Safety: Use appropriate protective gear, including gloves, to avoid inhaling carbon fibers when handling this material. Discard damaged panels.
  • Cut with waterjet, CNC, or fine cutting edges. The fibers are dangerous to your health when inhaled! Using a service to cut and shape this material is strongly recommended.
  • Unlike the glass fibers in G10, carbon fibers ejected from damaged CFRP can easily short-circuit electrical components in your combat robot. Protect all circuits and connectors from accidental contact with fibers.
  • Carbon functions as a shield to block radio signals from getting to your robot. Make sure your antenna is exposed to the outside is protected by a nonconductive panel instead of carbon fiber.

• Aluminium / aluminum composite panel aka "Dibond" or "Alupanel"
  • thin sheets of Al with a plastic between.
  • Very flat, generally good characteristics?

Metals

• Aluminum[6]: Super light and very easy to cut and use, but very soft. It can be used to absorb impact damage, but if dented, it will not spring back and may cause trouble with parts behind it. It can't stop attacks from metal saws. It is good for making very lightweight structural material and frames.
  • 6061: The most common aluminum alloy used in robot combat.
  • 7075: Slightly stronger and more rigid than 6061 but more brittle and extremely difficult to weld.
• Titanium: Malleable enough to be bent, but hard to cut through. Titanium[7] is used in all weight classes, from thin armor plate on 150g (US fairyweight) bots, to weapon arms, heavy plate and chassis material in BattleBots competitors. It's also a crowd pleaser: If you see a shower of bright white sparks when a bot is attacked, titanium is usually involved.
• Steel:
  • Mild Steel: Low Carbon steel which is typically lower in cost and easier to work with.
  • Tool Steel: High Carbon alloys that can be very strong and resistant to deformation and abrasion.
    • AR / Hardox: Through-hardened, Abrasion Resistant steel often used as armor in larger bots.
    • S7: Shock resistant alloy that is suitable for impact weapons.
    • 4041: Strong and easily hardened alloy. Often used as welded steel tubing in frames.

Fasteners

List of common types and what they do

• Nuts, bolts screws
  • Wood screws, and self tapping screws - create their own thread in softer materials, which gets weaker each time it's used.
  • Machine screws/ bolts - screw into a threaded hole, either in a nut, threaded insert, or material which has been tapped (had a thread cut)
  • Shoulder bolt - A bolt which has a "shoulder" - smooth machined section which can be used as a shaft.
  • Locking nut / Nyloc nut - a nut containing some plastic / rubber material which makes it self-tighten and resist e.g. vibrations.
  • Threaded inserts aka "Insert nuts" - an internally threaded part which can be pushed or screwed into a softer material to allow a machine screw / bolt to be attached strongly and repeatedly. Some types
  • Claw nut. Similar to threaded inserts, but intended to go into the back of a panel on a flexible material (wood, soft plastic e.g. HDPE) to allow a bolt to securely fasten.

• Rivets and other one-time fasteners
  • Pop-rivets - a fastener which can connect thin(ish) materials with access from one side only. Difficult to remove (must be drilled out usually)
  • Rivnuts / rivet nuts - a combination of a rivet and a threaded insert, i.e. a rivet with a thread inside so a machine screw can be screwed in - very handy.

Other hardware

• Magnets - Rare Earth or Electromagnets can be used to increase the apparent downforce in a bot giving it an advantage.
• Threaded rod - just a rod which is threaded along the full length so you can put many nuts on in different positions to e.g. hold parallel parts.
• Nut strips - a strip of (typically) metal with periodic threaded holes, perhaps at right-angles, to attach parts at right angles.

Parts for moving things

• Wheels (or hubs) hold tires and turn them. Some hubs come apart to make wheel replacement easier.
  • Tires are the part of a rolling bot that is in contact with the ground. Often a separate part that can be replaced. Good traction is important.
  • Mechanum wheels have diagonal rollers that allow a bot to move sideways on command.
  • Omni wheels have tangential rollers and can roll sideways, allowing for more agile motion, but less control than mechanum.
  • Non-driven wheels aren't powered, they just turn. Sometimes called idler wheels. If they swivel, they are called casters.
• Tracks, treads
• Axles, shafts, keys
• Bearings, pillow blocks
• Motors
  • Gearmotors
  • Gearboxes, transmissions
• Chains can transfer power from one shaft to another.
  • Chain drive allows two shafts to spin at equal speeds, or a fixed speed ratio.
  • Sprockets are toothed wheels that guide the links on chains.
• Belts can also transfer power from one shaft to another.
  • Timing belts (toothed belts) are also meant for fixed speed ratios.
  • V belts offer strong power transmission with a chance of slippage in case of harsh impact.
  • Round and flat belts are more likely to slip if one shaft is stuck.
  • Pulleys go on the shafts and belts are fitted onto them.
• Direct drive is when a motor is directly coupled to a wheel, weapon or other load.
  • Flexible shaft couplings are used to dampen high impact shocks from being fully transmitted back to the motor.

Types of steering and locomotion

Tank steering

Wheels or treads on the left and right side of the robot can be spun in different directions. Very common since it allows great freedom of motion. Sometimes called skid steering or slip steering (there may be excess friction as wheels or treads slide). Tank steering allows the driver to turn in place without traveling, called zero-turn steering or turreting.

Mechanum steering

Mechanum wheels can be driven in all four directions, allowing sideways or "strafing" motion as well as forward and back. This requires the use of at least 4 motors and wheels.

Ackermann steering

Often called car steering or servo steering, this is the kind of steering found on both real and R/C cars, where the front wheels both pivot to change the direction of motion, usually driven by a single servo. Easy to understand and drive, but because the robot can't turn around rapidly, it may not be able to react quickly to changing situations.

Single-wheel drive

A 3-wheeled type where only one wheel is powered and steered. Uncommon as it doesn't provide much traction for motion, and it may be prone to falling over.

Articulated steering

Some bots have been designed with a center-pivoting body. The amount of pivot determines the difference in angle between wheels in the front half, and those in the back half.

Melty steering

A Meltybrain robot spins in place using two or more driven wheels. Slight changes in the power applied to each wheel will cause the robot to travel to one side. Under computer control, the driver can command the slight change to repeat during each rotation, causing the bot to continue moving in a specified direction.