Thanks for that, very helpful.

I haven't got any tool steel small enough to bore a 10mm hole so may have to get some.

What about the pulley for the motor? It will only be a small motor with perhaps a 3.175mm shaft.

And yes, I do have an oscilloscope, a V2 DSO nano but how would I use a scope for balancing? I've seen people balance spindles before using a pair of accelerometers before which I don't really have access too so Im very interested where a scope fits in.

Thank you!