They are not square collets so won't hold square work. They are round collets that grip the round shank of a tap and have a short square at the end to stop the tap rotating in the collet, hence the name "square drive"

Edited By JasonB on 28/03/2018 18:31:11

Unless you've got a separate slippable clutch somewhere, I'm not sure the OP's version are an advantage.

Edited By Mick B1 on 28/03/2018 19:35:32

The 'rigid' term in 'rigid tapping' indicates that clutches are not part of the equipment .

3-D printed, presumably?

If you want steel collets to hold square material, it's beginning to sound the usual, one job begetting a load of others.

1) I want a square collet, so make an ER collet in steel with a bore just smaller than the square.

2) Make up a rotary broaching tool

3) Rotary broach the collet so that the bore then becomes square, (or what ever shape is needed).

Of course, 2 is going to spawn some other jobs, no doubt . Shades of "Dear Liza, there's a hole in my bucket"

At least you should end up with a load of rotary broaches of various shapes and sizes! Which will need storage making and a place found for it. See what Ii mean?

Howard