Advice on buying servos.

[Agathon]

Just out of interest, via a socket screw axial to the ballscrew, I used a precision torque screw-driver (usually used for very carefully setting the torque on small screws) to see how much torque was required to move the table. As might be expected the initial torque required to overcome the stiction was higher that what was required to keep it moving. However the maximum torque required was surprisingly low - 0.5 Nm. I might just pop a 16mm slot-drill in a collet and see how much torque is required to make it cut steel...

[Agathon]

Having thought about this for a few mins, I am now a little unsure that a 200W servo will be powerful enough for my table. The Omron R88M 200w motors produce 0.637 Nm continuous torque with a peak of 2.2 Nm.

I think I noted in one of my first posts on this forum about stepper replacement that Fehlmann now fit Omron 400W servos to the P21 which is a similar machine to mine (but with a slightly larger table) - I'd forgotten about this until doing some searches earlier on.

I suppose that if I do as you suggest Boyan and fit the servos with a 2:1 reduction a 200W Omron servo might be adequate. Being more optimistic, a reduction of 3:1 would produce the best part of 2Nm continuous torque - which will probably do the job.