SuperNova Geared Chuck

[GeordieTurner]

Hi, I just inherited a SuperNova Geared Chuck from 2004. How do I establish the thread size and can I fit an adapter, it has a fixed thread not an insert and I was told this type cannot accept an adapter to M33x3.5? Is this correct and why? Any help would be appreciated, regards Richard

 

[Simon_M]

This article has a table of sizes:

https://knowledge.axminster.co.uk/woodturning-chucks/?_ga=2.233846813.2010236957.1555498142-1688234302.1554158194

The real question is does it fit the lathe you have/want to have?

You can get an adaptor e.g. an insert or exert. The insert allows a smaller spindle to be used on a bigger chuck thread and an exert "allows" a larger spindle to be used on a smaller chuck thread. However it's best to avoid exerts because they are quite long and heavy and move the chuck and workpieces away from the headstock. Sometimes, older chucks had a back plate that could be replaced or taken off to be re-machined - good luck with that idea.

 

[Phil Pascoe]

and another - http://www.peterchild.co.uk/chucks/threads.htm

 

[Duncan A]

Edited comments from phil.p's posted link:
Patriot and Supernovachucks in 33mm x 3.5 thread and 1,1/2" are made with the thread cut directly into the body, as there is not enough room to take an insert. The thread in the Patriot and Supernova where the insert fits is 38mm x 3mm.
To ascertain what thread your chuck has, measure the internal diameter (ID). This can be done accurately enough with ordinary inside calipers for near-as dammit measurement:
M33 x 3.5mm ID is 29mm
M38 x 3.0mm ID is 35mm
1.5" x 6 tpi ID is 33mm NOTE: pitch is 4.2mm, quite a bit more than the M38 thread above.
These are NOT engineering tolerances but should enable you to find the thread diameter.
To check the pitch use a steel rule to measure across one single thread.
HTH
Duncan