What do you call this type of chuck?

I've seen lathe chucks rather like this drawing, specially for hold thin disks. Does anyone know what they are called, please?

A step chuck, a kind of collet. Two kinds, this is the concave version for holding outside diameters.

https://www.youtube.com/watch?v=UtBtaFUyo6Y

Bill

I've never seen a metalworking step chuck, only step collets. There are step jaws available for woodworking lathes however **LINK**

Brian

If you have a set of soft jaws for your 3-jaw, and you do regular work around 3 or 4 approximate diameters, they tend to end up looking like that...

They are primarily for clock/watch lathes so think in terms of diameters around 1".
Safe way to hold toothed clock wheels when rebushing etc

Pot chuck.

Very nice to use but not cheap, **LINK**

Niko.

.

Levin has them 'on offer, while supplies last' **LINK**

https://levinlathe.com/StepCollets.htm

[thankfully, over the years, I have collected a useful range secondhand !]

MichaelG.

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Edit: The male version [for holding the job by its bore] is less common, but nicely shown here:

http://www.nielsmachines.com/en/lorch-las-llk-lan-step-collets-set-and-ring-colle.html

Edited By Michael Gilligan on 14/09/2018 19:14:31

I have 5C collets with blank ends to bore out like those

Thanks guys. The expense and size puts them out of reach for my requirements. Even if I could afford one it would need to have a capacity of up to 75mm. I'll have to stick with making individual holders.

When I bought mine, (secondhand) they were described as "Bell Chuck). Don't see a lot of use, but invaluable when the need is there. As part of the deal came some male versions. So washers can be held either on the OD or the ID.

Howard

In the U.S. the commonly encountered chucks of this sort come with a 5C collet shank (as Chris Evans notes). The shank may be integral or separate.  Hardinge calls theirs "Step Chucks". These have an integral 5C shank. The ones they supply of unhardened steel are called Emergency Step Chucks. You bore to the size or sizes of step(s) you need. Hardinge also supplies these hardened and ground in a variety of sizes, each with only one "step". I get the impression from their website that they are phasing out the hardened and ground ones. The O.D. of the head on these has a taper which is pulled in to a closer which Hardinge makes for either their tapered or threaded spindle nose (they may have these also for type A spindle noses as used on their CNC machines). Monarch did make a set of compatible closers for the D1-3" spindle nose on the 10EE. I was lucky to find on ebay one of these for the 3 inch step chuck.

Another U.S. company, JFK Company, makes a couple of iterations of this. One they call the "Step Collet". It has a steel shank that includes the 5C closing taper and a head to which "pads" either steel or aluminum, are attached with socket head cap screws. One then bores out to the size or sizes needed. They call their other version an "Oversize Collet". Here the head, either steel or aluminum, includes the 5C closing taper. This head then screws on to a back piece of steel which is threaded to fit the 5C drawbar.

There are additional makers of these sorts of 5C collets. They may have their own names as variations on a theme.

David

Edited By David Lindquist on 16/09/2018 02:02:32

Edited By David Lindquist on 16/09/2018 02:03:07

Edited By David Lindquist on 16/09/2018 02:04:14