Lesson 2: Tools and Fasteners
The basic tools we will use are:
- Torx (or star-drive) T15 screwdriver for tightening and loosening screws
- Torx (or star-drive) T8 screwdriver for tightening and loosening shaft collars
- Open ended wrench used with standoffs and nylock nuts
- T15 Allen wrenches (or L-wrenches) for hard-to-reach screws
To assemble our parts, we use size #8-32 screws (8 is the diameter and 32 is the number of threads per inch). They come in many different lengths (from 0.25 inch to 2.5 inches).
You should always use the proper length screw. Too short and it won’t reach, or there won’t be enough threads for the nut to tighten. Too long and you will waste a lot of time tightening and loosening the nuts or, worse yet, the screw will stick out and interfere with other parts of your robot.
Nuts are used to hold the screws in place. There are two main types of nuts used in VEX robot building:
- Keps nuts (which have an external tooth lock washer and are strong while still being removable)
- Nylock nuts (which have an internal nylon lock that makes it perfect for strong, permanent connections)
Keps nuts are easy to tighten and loosen. They can often be “finger-tightened” or held in place with just your finger. These are good for rapid prototyping or building parts that will quickly be disassembled. Nylock nuts require the use of a wrench. These take more work to assemble and disassemble, but won’t easily be shaken loose. Here is a video demonstrating how different types of fasteners stand up to being shaken:
And, of course, never forget…
Two things to avoid when using our tools:
- cross-threading screws (when a screw is put into a nut at an angle… it doesn’t want to turn, but you force it anyway…)
- stripping the head of a screw (when you put a screwdriver into the head of a screw at an angle and tear up the metal…)
