Originally Posted by IndyRC_Racer

My advice to anyone using M3 machine threaded screws on plastic tub chassis is to use a thread forming tap such at Tamiya 74068 (https://www.tamiyausa.com/shop/optio...d-forming-tap/). I believe this part may be discontinued.

I have struggled in the past when installing M3 aluminum screws into new Tamiya TT02 lower decks (chassis) even when using a good tool tip/bit. What I do now is at least use a STEEL M3 screw to create the thread into the plastic before I try using softer or lighter screws. Obviously a tap will do a better job cutting a thread. The steel screw does a good enough job most of the time. While this may seem like an extra step, it has saved me from ruining/stripping the socket head on the "good" screws.

If you DO buy a thread forming tap, make sure the pitch of the threads is the same at the pitch of the screws that are being used. The Tamiya tool has a .5 pitch. I tried buying a cheap tap online and it didn't work well for me so I just use an M3 steel screw instead.