# Mini lathe backplate



## savarin (Feb 19, 2021)

A good friend of mine has a ubiquitous Chinese mini lathe.
He wanted to mount a 5" 4 jaw chuck to it but the existing back plate is too small and also an integral part of the spindle.
A bit of thinking and we decided to make a large ring and weld it to the original back plate.
First part was finding a large enough chunk of metal, none available so join some up


Yep, thats large enough


Full penetration welding from both sides one bead at a time in an effort to control distortion.


It seemed to work so chop all the corners off


add a drive pin and turn round


then face off both sides


bore out to fit the outer dia of the spindle plate


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## savarin (Feb 19, 2021)

Fits ok


so weld it on, chamfered each edge but didnt do full circumference welding but it is welded both sides
trued it up between centres and faced off both sides again. eventually got to zero run out here but once installed he had to remove 0.03mm run out which was easy.


Next made another ring to sit inside the chuck register, bored it out with a hole cutter


It sits nicely just below the surface of the chuck and the original register on the spindle fits into the ring.


Made a quick transfer punch and drilled the bolt holes


and bolted it all up


Now he can use the original 3 jaw or the new 5" 4 jaw.
It needed a quick touch up once the spindle was installed on both the face and outer edge to get to zero run out.
All in all a simple fix and he's well pleased.


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## mikey (Feb 19, 2021)

Nice job!


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## Aukai (Feb 19, 2021)

Very satisfying I'm sure


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## savarin (Feb 19, 2021)

Latest report is it cuts smoother, finer, better finish.
The heavy chuck does act like a flywheel so takes a bit longer to come to a stop.
All in all he's well chuffed with it.


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