Originally Posted by
Kontact
It doesn't work like that. There is no magical shape you can put into a round, stripped hole that is going to create a shoulder to torque against.
You grind it with a mini carbide burr to move each corner outwards - then the next size of hex key doesn't hang up on the corners and can be pounded in, so it engages with the part
next to where you ground it out. Or of course you can weld a nut on it. 😁