Cushman scroll drill chuck
- Thread starter Graeme
- Start date
RTM
Well-known member
Some history here, makes it sound like lathe chucks were a huge part of their business. Maybe it’s lathe and not drill?
Ill have a read, thanks.
I mean drill bits, rather than drilling machine. I assume it's always been intended for a lathe tailstock. Seems a little clunky in use for a pillar drill.
Probably slower to use with no real advantage, and must be more expensive to make, so the idea wasn't dominant.
Provincial
Well-known member
Can you verify that it fits a MT1 taper? Does the taper have internal threads in the small end?
It is unlikely that it was intended to hold drill bits. The design will not apply a lot of pressure to the drill shank, unlike normal drill chucks.
I suspect that it was made for work holding , rather than tool holding. Perhaps in a lathe or dividing head with a MT1 spindle hole that didn't have any mounting for a regular chuck because it was intended to hold work between centers.
It is unlikely that it was intended to hold drill bits. The design will not apply a lot of pressure to the drill shank, unlike normal drill chucks.
I suspect that it was made for work holding , rather than tool holding. Perhaps in a lathe or dividing head with a MT1 spindle hole that didn't have any mounting for a regular chuck because it was intended to hold work between centers.
I will verify tomorrow, I've not checked yet, it looks close though.
No thread in the small end, I assume your thinking draw bar? It has a locating tang.
I just don't see it as being for work holding. If it was, the body wpuld be a different shale, or the jaws would protrude more. It would be drastically limited in its capacity. It can only hold bar stock up to 1/2". You can get a disc in the end up to 1" maybe, but you only have maybe 1/8" of jaw stick out to grip. If it was ment to work that way the body wouldn't shroud the jaws so much.
The argument that it won't hold with as much pressure as a normal drill chuck, then why not use a normal drill chuck for whatever work holding this would be for?
It has the same holding capacity and the same mounting as a normal drill chuck so there would be no benefit to this for work holding either.
Maybe this is why its unusual.
Maybe it didn't solve any problem.
I imagine it's more expe dive to make than a normal drill chuck, possibly doesn't work great as a drill chuck, and won't hold any work that a drill chuck wouldn't.
Could be a solution to a problem that didn't exist and therefore passed into forgotten history.
Would be nice to know how Cushman marketed it though.
Maybe it didn't solve any problem.
I imagine it's more expe dive to make than a normal drill chuck, possibly doesn't work great as a drill chuck, and won't hold any work that a drill chuck wouldn't.
Could be a solution to a problem that didn't exist and therefore passed into forgotten history.
Would be nice to know how Cushman marketed it though.
tombell572
Well-known member
That's an interesting little chuck--never seen one like it. As Provincial noted, I agree that it is intended for work holding similar to a typical but larger 3-jaw lathe chuck. See what kind of fit you get in your lathe's spindle. It could be handy for smaller work pieces.
Tom B.
Tom B.
Provincial
Well-known member
Is it possible that it originally rotated on the adapter and is now frozen up?
tombell572
Well-known member
Possibly part of an armature undercutting set-up for a lathe? Check Page 7 here: "Special Chuck for Tailstock Spindle"
Tom B.
Tom B.
I don't think so. It's exactly like a drill chuck, but the jaws are on a scroll.
The arbour seems to be a taper fit in the chuck body.
The tailstock chuck recommended I that works like a drill chuck but has brass jaws. This could be used in the same way, but so could any drill chuck.
I wonder if the scroll mechanism is more accurate for centering, in which case I could see the benefit in using it in that kind of set up.