Anybody ever see a collet system like this?

[rwdenney]

This came with my recently acquired SB 14-1/2:

It’s threaded for the uncommon 2-1/4”x6tpi threaded spindle. Here it is after removing the tightening cap:

The angled insert is 1-1/2” in diameter, and I have a range of sleeves that insert into it.

Here’s the 1” insert pulled out of the outer sleeve:

Ring any bells?

I haven’t critically measured it, but - 1” shaft held in the 1” collet showed no hint of runout.

Rick “great for sizes the stock 4C collets won’t reach” Denney

 

[extropic]

Interesting.
I've not seen it before.
By the rough surface texture on the collet OD, my guess is shop made and not very hard.
Are there any features on the nut for a pin or wrench? Or, is it hand tighten (or strap wrench) only?
Is it possible that the whole collet chuck is mounted to a more common threaded spindle? Or, is that long threaded OD integral to the lathe spindle?

 

[benmychree]

It looks shop made.

 

[rwdenney]

I agree with both of you that it looks shop-made, but I wondered if it’s a standard design. The slits are not all perfectly straight, for one thing.

It has a hole on the base and the clamp collar for a pin spanner, and the spanner it came with is definitely shop-made—from 1/2” aluminum plate with a steel pin doing the work. I’m glad of that because I only have one decent strap wrench and I use that for the lathe cone pulley.

But that inset bronze thrust surface is a nice touch.

I don’t have a way to test hardness but I’ll compare it to some stuff. I’m not sure it needs to be particularly hard to be effective. I need to clean it all up, too.

This toolroom lathe supposedly came with a collet closer and drawbar, but it wasn’t with the lathe and I sourced it separately. But the 4C collets only go to 3/4, so this is nice to have. I need to break out the dial test indicator and measure the TIR, now that the lathe is back together.

Rick “lots to measure at present” Denney

 

[extropic]

Is it possible that the whole collet chuck is mounted to a more common threaded spindle? Or, is that long threaded OD integral to the lathe spindle?

So, I guess the answer is, the whole collet chuck is an attachment to a more common spindle configuration.

 

[extropic]

If the existing dimensions allow, it would be a neat trick to rework the collet chuck body into an ER40 (or ER32) collet chuck.
That would give you some modern utility.

 

[rwdenney]

So, I guess the answer is, the whole collet chuck is an attachment to a more common spindle configuration.

Sorry, didn’t answer that. There are four parts. The base screws onto the spindle, and provides the internal taper for the main 1-1/2” collet. The collar screws down onto the base, pulling the main collet into the base. The sleeves fit into the main collet to hold smaller diameters.

Presumably the base could be made to fit any spindle.

Rick “the lathe has a threaded spindle, but not the threads in the pic” Denney

 

[rwdenney]

I cleaned it up and did a bit of measuring. Here it is with a piece of 1-1/4” bar stock in it.

The bar measured within about a thou and a half, which is better than a 3-jaw, and about the same as I got with a 4C collet (a Hardinge collet in the South Bend closer). That sent me to measure the inside of the spindle and that was within a couple of tenths.

There was enough wiggle room to allow the bar to be bumped to within a thou at the free end.

I have a range of sleeves as seen in the bottom drawer of the toolbox. These extend from 1/2” to 1-1/4” in eighths, plus 15/16”, and of course the 1-1/2” tapered master collet. They compliment the 4C collets I own that max out at 9/16”. (The spanners, both the Martin commercial one and the shop-made aluminum spanner that fits the collar are in the same drawer.)

And, yes, they are soft, or at least softer than a file.

Rick “betting these are as good as the usual cheapie ER collets now for sale” Denney

 

[brino]

hmmmm....
I've never seen it, but it looks like a collet within a collet.
With the cumulative errors I suppose.
Brian

 

[GeneT45]

Looks like a step chuck to me.

GsT