# What is this thing on my lathe? Any ideas?



## djb25 (Aug 26, 2014)

Hi everyone, 

I recently purchased a Clausing 5904 that came with an odd piece mounted on the spindle. I would say it was a chuck, but it doesn't actually seem to have any function. I'm curious if it may actually be a part of some larger assembly. 

Here's a shot of the the item in question, shortly after unloading:




It's actually a round disc attached to a Bison backplate. It's pretty nicely machined and has a nice, tight fit with the backplate. 

Here's a shot of the back of the item, after removing the backplate:





The seller told me that the lathe had been used exclusively with collets before it was removed from the machine shop. It sat for about five years before I bought it. I'm thinking that it might be part of some sort of collet closer? 

After cleaning the thing up in the electrolysis tank, a distinct mark was visible on each side of the nose:




Any idea what this thing is?


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## Don B (Aug 26, 2014)

My guess would be an adapter for different chucks that where meant for a different machine, I have one I made that is similar to it for mounting my Emco 3 jaw on my Myford.


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## chips&more (Aug 26, 2014)

If there are four opposed marks on it it was probably used for a self-centering chuck. The large center protrusion and marks are typical for said chuck. And I think it’s shop made and just a chunk of metal, I wouldn’t sweat it unless you have a chuck that would work with it. And you made a nice score, I think you will be very happy with that particular lathe, it’s very desirable. If you read some of the forums on its vari speed assembly, you could easily get a bad impression about the design of it. I find that forum talk a bunch of folks with no/limited knowledge on its modulus operandi and just want to make noise. If you need any assistance you can PM me…Good Luck.


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## kd4gij (Aug 26, 2014)

Is the bore tapered.


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## billdeme (Aug 26, 2014)

I may be wrong but ut looks like a collet adaptor. The "bruise" marks are from the centering set screws.


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## darkzero (Aug 26, 2014)

Looks like just a shop/home made adapter for an adjustable chuck (ie Set-Tru, Adjust Tru, Setrite). The marks on the nose is where the chuck's adjusment screws make contact with the adapter to adjust the TIR.


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## billdeme (Aug 26, 2014)

Either was its an adapter plate of some sorts. The chuck in question was definitely adjustable due to the marks. Being the seller stating it was fitted exclusively with a collet set I would lean that way. My Cincinnati hawk is fitted with an adjustable collet set to remove any spindle to collet run out.


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## Vladymere (Aug 27, 2014)

It looks like the back side of my Prat-Burnerd set true chuck. which is sandiwiched bettween the chuck and the L00 spindle backplate.

Vlad


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