Glossary

COTS (Commercial Off The Shelf)
Parts that can be purchased from a vendor that are not custom made. The opposite of fabricated parts. COTS parts are not counted against the withholding allowance as long as they are not altered or part of a custom assembly.

Fabricated
Parts that are custom made and not commercially available. Fabricated parts are counted against the withholding allowance. COTS parts, once modified may be considered fabricated parts.
Withholding Allowance
At competition teams are allowed their bagged robot, COTS parts, tools and a withholding allowance, which is up to 30 pounds of fabricated items which can be added to their robot. Other items can be fabricated at the competition, but not before, unless they fit within the withholding allowance.
Bagging, Bag Day, Bag and Tag, Stop build day
Our robot must be bagged, in the elephant sized bag provided and locked with one of the blue tags provided at 9pm PT. Up to 30 pounds may be kept outside of the bag to continue working on. This does not include unattached batteries and motors, which may also be kept outside of the bag and do not count against the withholding allowance unless attached.
Fasteners and Fastening methods
Machine Screws
The screws used on the robot are mostly 10-32 Socket Head Cap Screws (SHCS) These are used because of their strength and the resistance to stripping. #10 refers to the width of the shaft and 32 is the treads per inch. #10-32 is a fine thread used when the screw is connecting to threads in metal or a metal nut. #10-24 is the same size screw, but with coarse threads used for screwing into plastic or wood. Hand check the nut fits, because putting a coarse nut on a fine screw or vise versa will strip the threads, be excessively hard to attach or remove and not provide a strong attachment. #10-24 thread cutting screws are used to attach the toothed belt pulleys to the plastic wheels in the drive train. Use a 7/32 drill bit to create holes for a #10 screw.
Other Screw Types:
Button Head Screw
A low profile rounded head that is also driven with an allen key or hex driver. Used where a socket head screw might catch on an object, like the underside of the robot.
Hex or HexWasher
used with a socket and ratchet or a wrench. These are generally larger bolts or screws which need a larger tool to engage the head.
Flat Head
A screw type that requires counter sinking, but will sit flush against the surface. A countersink bit is used to drill a cone shape into wood or metal so the screw can sit down inside the depression.
Wood Screws
The recommended fasteners for 2×4 comstruction are star head deck screws. The star or torx head eliminates stripping of the screw which can be a significant problem with longer screws.
Black drywall screws are not recommended when there are significant loads as the heads break off easily. They are intended for holding up drywall, not plywood.
Fastener Charts
Welding
Welding is the joining of metals by melting and joining. Additional material is added by using welding rods. A proper weld is often stronger than the surrounding material. The heating of metal can actually weaken the surrounding area and a crack may happen next to a weld. Different metals vary in their weld-ability. Cast Iron cannot be welded, Steel can be welded by a multitude of methods. Aluminum can be welded with a Tig welder, among the more expensive methods. Note, welding requires training and is dangerous if you are not aware of all the considerations and proper methodology. Dangers include thermal burns, ultraviolet burns, damage to eyes from ultraviolet exposure, and fumes inhalation which can cause coughing, pneumonia, and, with some metals, are carcinogenic. Proper ventilation is critical.
Brazing
Brazing is the joining of metals by melting a filler metal with a lower melting point and essentially gluing the pieces together. Filler material is added by using brazing rods. A brazed joint is often stronger than the surrounding material. Since the metals to be joined aren’t heated as much, they retain more of their strength. Aluminum can be brazed with a propane or MAPP gas torch. Different brazing rods may require different temperatures and may require flux. Brazing temperatures may range from 350 to 700 degrees Fahrenheit. High Temperature brazing rods and large masses of metal may require an oxy-acetylene torch. Like welding, brazing requires training. Dangers include thermal burns. Any fumes should be considered toxic. Soldering, brazing and welding all require adequate ventilation.
Soldering
Soldering is a lower temperature method of joining metals with a filler material. Soldering is most often used for joining copper pipes in plumbing.  Soldering used for pipe joining is different than solder used for electrical wiring.