Quote Originally Posted by Muzzer View Post
I'm doing that right now on my lathe conversion. As Mud says, LinuxCNC and some other controllers can do it (excluding my Centroid Acorn and Newker 990 of course).

The signals from linear encoders are generally like rotary ones ie quadrature A and B with a Z index, either single ended or differential.

But I detect that old chestnut again here. You still need to get as much backlash out of your system as you can sensibly manage. PID controllers really don't like sudden nonlinear behaviour. I use the analogy or driving an old banger along a winding hilly track with half a turn of slop in the steering wheel. You (the closed loop controller) have to work bloody hard to keep on track. There's no magical solution that allows you to produce precision parts on an old dog.

Same applies to backlash compensation in your controller - in some situations it can actually double the backlash error. And if you are missing steps, you need to find out why and fix it.
Using the same analogy why not just replace the track rod ends on your old banger?
The lathe cross screw can be easily replaced with a ball screw, and with a bit of ingenuity, using only basic workshop techniques.
Having removed the worst of the backlash, using modern stepper motor controllers that incorporate feedback circuitry for encoders can we then connect dro scales directly?
I would try this right now but I don’t have a dro although my lathe is fitted with encoder steppers operating directly from a mpg with no computer required.
Is it worth buying a dro to try it or is it a no-go?