Allison collet chuck

[Bob Engelhardt]

"Allison?" Yeah, I never heard of them either. An extinct and rare bird.

Anyhow, the chuck threads onto the spindle and has a stationary part and a rotating part. The stationary part is held that way by a lug on the side. The chuck is tightened by moving a lever on the side of the stationary part which cams a cylinder forward and closes 2 tapers onto the collet.

The question that I have is: can stock be inserted and removed without stopping the spindle? I can see that it's theoretically possible because the tightening mechanism is stationary, but is it realistic?

Thanks,
Bob

[DR]

You have to examine it carefully to determine if the bearings can handle speed.

I bought a similar type chuck from a local tooling house. They claimed it was rated for high speed. It wasn't, it was only meant for low speed rotation like you'd have with a rotary table.

[Toolguy]

A lever collet closer with the lever on the left end of the lathe will open and close at speed. I've done that thousands of times when changing parts. The parts usually have a feature that stops against the collet face or there is a collet stop inside the collet.

I have never seen the kind you have, so don't know about that one.

[754]

It is possible, on my Hebert turret you could do that. It had a row of 1/2 ball bearings behind where yours has a recesssed flange .
It may have been reffered to as a dead length chuck ? I think that meant th e part does not move in or out as it gets gripped.
Ba most handy setup for workng on the opposite end of a bushing. ..

[alanganes]

That's an interesting setup Bob. Did you get it with a set of collets? I don't imagine you can find those so easily,

A place I worked had a 5C collet chuck that was vaguely similar in that it was all mounted to the right of the headstock and did not use a drawbar. The chuck body had a part the hung down and clamped to the space between the ways, in a manner similar to a steady rest, to keep it stationary. It had a lever handle that pointed straight up that you moved left or right to open and close the collet. It was designed to be used with the spindle running. It was on a small (maybe 9") old SB of some sort.

[Bob Engelhardt]

Does anybody want this? 7 collets: 1" to 1-1/4 by 1/16ths, 1-3/8, 1-1/2. Back plate is threaded 2"-8. Heavy, but would fit in a large flat rate USPS box - you pay shipping ($19).