In need of 6" Chuck backplate with 55 degree threads

[Mark4]

I'm looking for someone to make me a roughed out 6" backplate for a Tru-Adjust style chuck. It is to fit a Boxford ME10 that has 1 1/2 x 8tpi WHITWORTH thread. I can finish it for fitting but I am unable to make it because it will not fit in the 3 jaw chuck I currently have and I do not have 55° internal threading tools.

 

[Jim F]

You can grind a threading tool.
Do you have a faceplate to mount a blank to ?

 

[RJSakowski]

I would make a secondary plate that could either be mounted to a faceplate of with a shank to fit your three jaw. Mount it to your blank with three If you don't strategically placed screw. The three extra holes won't affect the function of the backplate..

Edit: Right @Jim F, You don't even need the secondary plate if you're careful about location of the fasteners.

 

[Illinoyance]

If you make your own backplate you should first make a gauge that duplicates the threads and pilot of your spindle.