[jheers]

I am loading a 21/32 inch drill into an ER32 collet, and the only drill I have available had most of the shank ground down to a half inch. I don't have any half inch collets available, so I'm trying to clamp onto what's left of the shank. I have about a .625" length of full diameter shank left. Is 5/8" long enough to hold a 21/32" drill reliably? I am using it in a lathe on 1018 steel, drilling about 3" deep.

[txcncman]

Yes.

[jheers]

Thanks. Saves me a headache. Seems like no matter how many half inch collets we buy, there are never enough.

[Orange Vise]

I wouldn't recommend doing this regularly.

Most ER collet manufacturers will typically recommend clamping a shank that is at least 2/3rds of the collet length. In the case of an ER32, the total length is 1.58", so clamping only 0.625" = 40%. If you overtighten the collet nut, the collet could split.

You may be able to do this occasionally to get you out of a bind, but it really isn't ideal and will eventually cause damage to the collets.

[Geof]

Drills do not experience a side load so you can get away with gripping a length less than one diameter. On milling cutters it is better to grip a length equal to 1-1/2 to 2 diameters.

[uli12us]

It were better if you take a small disc with 1/10" height to the end of the collet. The disc must not be bigger than your drillshank, a little bit (2 thou) smaller isn't bad.

[wizard]

While you may get away with it you will ruin the collet eventually. You also run the risk of spinning in the collet. As for the drill bit did you slap the guy that turned the shaft down? I only ask because normally when you see such in a shop, said drill bit will suffer from excessive run out.