Écrou taillé un peu comme une pince ER32.
Reçu dans ma boîte mail hier, origine :
Machinist Workshop
C'est de l'anglais, traduction en ligne possible pour les réfractaires...
Screw Holding Made Easy
by Al Hanson
A while back I needed to modify a flat head screw for a special purpose. I couldn't buy a screw that would fit the need, so my lathe came to the rescue! At the time, I didn't have any lathe collets and didn't want to ruin the threads by clamping in the three-jaw chuck. I know some guys just slit a nut, but the solution shown in the photo is what popped into my brain.
The idea was to make a nut work like a real collet. I just slit each flat on the nut, using a cutoff wheel in the Dremel. I cut a little more than halfway through, alternating the sides on each flat. It worked great – no slippage and no messed up threads.
It takes very little pressure to tighten the lathe's three-jaw chuck, and it releases the screw completely when the chuck is loosened.
I was concerned that the nut collet might stay crushed after it was clamped and in preparation I bought a grade-8 nut. I shouldn't have worried though, as the grade-5 nut sprang back to normal once released.