Washout, Geoffrey,
Thanks for comments on the Spitfire - its a mk9 (nicest shape I think!) and has taken 3 years on/off (mostly off) to get to this point.


Neale,
Have you got any photos of the machine you could post? Might help gauge stiffness.

Are you sure you are not loosing steps - the deeper cut is higher load on the leadscrew and delrin nut. I confirmed my machine was missing steps a while ago by touching the stepper motor body during cutting - I could feel the kick every now and again. I think mine was an extreme case so instead you could also set up a DTI on the tool, gantry, or Y axis plate when it is all at the home position, cut out the shape and then see where the machine homes back to. DTI should be back at zero, otherwise there has been a step or so missed.

What is the control system spec, voltage, drivers, BOB etc?