How to fix three jaw chuck

Dell

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Hi all
I need to use a three jaw chuck to make something for a non clock related project so I need to be able to fix it to my lathe, the chuck has three screws to fix it to an arbor and I have a spare Lorch 8mm wax chuck so I am wondering what is the best way to drill and tap it For accuracy because if it is very slightly out it would be scrap.

Any suggestions would be much appreciated

Dell
 
Does the back of the chuck have a recess or some other type of registration? Not an expert on watch lathes, but usually a backplate is involved in fitting a chuck to a spindle- can you make an intermediate piece like that to accept the chuck?
-Mark
 
Make a new arbor mount it to the chuck, hold a precision ground rod in the wax chuck and hold the ground rod in a 4J or set-tru 3J and zero out the TIR, support the arbor end with a live center. True up the arbor.

Alternative would be to just make an arbor bolt it to the wax chuck and hold the arbor in an adjustable chuck and zero out the TIR of the wax chuck. A bit unclear as to what you are mounting the wax chuck to or what your setup is.
 
Yes the chuck has a recess but the wax chuck only has 1/4” of meat not enough to turn a bit off as you can see from the pictures it has a fitting with a 14X1.5 thread and I can only find 14X 1 the chuck is a unimat not the best I know but for what I need it for it will be okay and the lathe is a IME watchmakers, I know I said I had a Lorch 8mm wax chuck but it is the same thread.

Thanks Dell
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Tough to do without another lathe- what you need to make is a stub arbor which fits the spindle on one end (I assume that is a collet arrangement) and has a 14.5 mm male thread on the other.
Wait- what about modifying the wax chuck (or buy another one) to mount on the back of the unimat chuck in place of the 14.5mm adapter piece? I assume that is the piece in question in the third picture? If so then turn the wax chuck to have the proper fit up and drill and tap 3 mounting holes. Done.
You would need a precise fit on the inner rear bore to achieve perfect concentricity. You would cut a step on the face of the wax chuck to perfectly match the rear bore in the unimat chuck.
 
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I have made mounts for several watchmakers lathe chucks using this product from Sherline.


A photo of a six jaw chuck with the Sherline mount is attached.
1591622107257.png

I did the machine work on my Sherline lathe, which has a WW collet holder. The work could also be done on a watchmakers lathe IF you are equipped with a cross slide I suppose.
 

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