I got an e-mail today asking "how do I stop a threaded chuck comming undone when using on a rotary table?"

Not having used lathes with threaded chucks I could not give an answer except do it up tight. I know some people have screws to stop the chuck comming off the lathe spindle but do they just act as a safety measure or lock the thread solid which would be needed if say dividing on the rotary table.

So the question is for those of you that have one of the MT adaptors that fit into a rotary table to screw your Myford chuck onto is how do you stop the cutting forces from the milling cutter unscrewing the chuck?

Thanks, J

When using on a lateh the cutting forces tend to tighten the chuck, its only if you stop the spindle suddenly or run in reverse that there is a risk of it comming undone. Also to some extent the same with flycutting although part of teh cut will be acting against the thread direction. >>

The backplate is what I use but kind of defeats the idea of being able to leave work in the chuck after turning so you keep it concentric, and a chuck with integral Myford thread may not be the easiest to centre and bolt to a table/backplate>>

Take a cut like this, the work is rotating clockwise yet the cutting force from the endmill is trying to push the work clockwise which could unscrew the chuck.>>