Improving a lathe spindle head.

[tonyfoale]

The spindle thread was a real bastard at 50mm diameter, 8TPI. I recently found 2 backplates on eBay that fit this thread. They were slightly too tight of a thread fit, so I got them centered in a 4 jaw, and retimed the thread so I could use the lathes power feed with an internal threading bar. I manually rotated this assembly to scrape the interference fit. So much for mass manufacturing with interchangeable parts.

Mine came fitted with an imperial spindle thread but also with a metric thread spindle. I use the imperial thread because the chucks and face plate which came with it fit. To change to the metric one would entail new back plates etc for no benefit. Without going down to measure I do not recall the dimensions. I have an assembly drawing of the complete head and that shows two different part no.s for the spindle labelled metric and imperial. The previous owner bought the second spindle.
I am not a fan of screw on chucks, I much prefer a taper fitting like my old Colchester Student had.