Chuck backplate

[Brian WoodParticipant @brianwood45127]

[Brian WoodParticipant @brianwood45127]

Hello everyone,

I have a backplate for threaded nose fitting removed from a 5 inch Pratt 4 jaw chuck and no idea what it used to fit.

The thread is 1 5/16 inch by 11 TPI Whitworth form. It seems an odd size that I can't match so can anyone identify it please? The nose register diameter is also 1 5/16 inch.

Brian

[JasonBModerator @jasonb]

Are you sure its not 1" BSP which is 1.309" very close to 1 5/16" and 11tpi

Can't help with the lathe it went on but could it be someone was intending to use a pipe flange as a backplate and never got round to rethreading?

[Brian WoodParticipant @brianwood45127]

Hello Jason,

Thank you for that information, the sizes are too close to sort, so you may well be right..It has been machined tike a lathe backplate too and I never thought it was anything else when I fitted a Myford plate to the chuck in it's place.

I can always bush it and remachine it for my use, but it might just suit someone as it is

Regards Brian

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