Is the use of lock washers on the motor screws legal?
Normally I would have said no as they are not sold by VEX and therefore are illegal under rule R6.
<R6> Official VEX products are ONLY available from VEX & Official VEX Resellers. To determine whether
a product is “official” or not, consult www.VEXrobotics.com.
However, rule R7 states
***<R7>*Robots are allowed the following additional “non-VEX” components:
c. Any 6-32, 8-32, M3 or M4 screw up to 2" long, and any commercially available nut to fit these
screws.
So if a screw with an integral lock washer (or [this) were commercially available it would be legal therefore making the lock washer itself legal.
These types of screws with integrated lock washers would be legal, as per <R7> quoted above. However, removing the lock washer and using it separately from the screw would not be legal.
The real question is can I use a lock washer on an existing 6-32 VEX screw? or do I have to purchase the screw with the integrated washer to make it legal. They would be functionally equivalent, however, in one case they are purchased as a pair, in the other they are purchased as two separate parts.
If the lock washer is not integral to the screw (i.e. Is the lock washer permanently attached to the screw?), it cannot be used. The rules permit for the use of any commercially available 6-32 screw. However, just because the screw is sold with an accessory, does not mean you can use the accessory. If the accessory is an integrated part of the screw then you can use it as a single entity.