Reply by jmos

The collet of my PC has jaws that are about 1-1/4”, I can push the bit further than that to bottom it out, but the end would be past the jaws. As the collet grips by wedging the leading edge of the collet onto the shaft, thus pinching the collet around the bit, I would be hesitant to insert the bit less than 1-1/4”. You could probably run it out slightly (say an 1/8”) but too far and tightening the collet would tend to close the gap in the collet fully before actually tightening down on the shaft. It may seem hand tight, but under load it could slip, or worse, come out.

As Renners asked, what’s the application, maybe someone can come up with a work around?

-- John