Mystery lathe backplate

I have just bought a new 4" Burnerd chuck with both sets of jaws, model N30. Definitely imperial as the fixing screws are 1/4" Whitworth.

It came with a backplate which I have failed to identify, even by googling.

The backplate is held on the spindle by three 5/16" BSF studs at approximately 49mm pcd. From slight witness marks the flange of the spindle is 62mm diameter. A tapered projection of the spindle around 36mm with an included angle of about 11 degrees centralises the backplate.

Someone must know.

A picture would help to identify please.

David

If the chuck is new, it seems odd that the fixings are 1/4 BSW, rather than Metric. But given that, you would expect the the other dimensions to be Imperial also, rather than Metric

The closest Imperial size to "approximately 49mm" would be 1 29/64" (1..9219" ),

or more likely 1 15/16 (1.9375" - 49.2125 mm )

Howard

I will try and post a couple of pictures. The chuck is unused but pretty old, made in England, definitely predating the metric 100mm versions. Having stripped, cleaned, lubricated and re assembled it is a beauty, both sets of jaws are tight and body and jaws serial numbers match. I couldn't resist the price, £45.50 including postage.

Edited By old mart on 10/06/2019 12:47:00

The mount on the Siege SC6 looks a bit like a contender.

http://www.mini-lathe.com/C6_lathe/C6/c6.htm#Chuck and Chuck Mounting

If it old, but unused, I would expect the dimensions all to be Imperial.

However, that would not stop someone from making a backplate with a Metric OD, and fixings.

But the register would still need to be Imperial, as will be the PCD for the Backplate/Chuck fixings.

Howard.