Sounds good. So is it now cutting the same for a 4 arc circle as a 1 arc circle?
Is it seeing that there is a join in the arc and thinking about it?
It shouldn't be if CV is doing what it's meant to. Just to re-state: If CV is working properly there should be absolutely no reason for it to cut 4 tangentially meeting arcs any different to a single arc. i.e. there is absolutely no need for a speed change OR for any rounding at the "joins".
Is that a characteristic of stepper motors?
Not sure what you're meaning. Is what a characteristic of stepper motors?
The look ahead is set to 200 lines as recommended by mach handbook.
Hmmmmm. Where does it say this? My default was 20 and my manual says it shouldn't need changing and indeed I never have.
Lookahead tells the planner the maximum number of sequential feedrate moves it should consider at any given time. The maximum number of sequential feedrate moves in the whole code you posted was only 20. I think you can see where I'm going...
I realise that I may be barking up the wrong tree here but would a smooth stepper improve the performance?
With Mach I've learned never to say never. But if we're still concentrating on why a 4 arc circle cuts differently to a 1 arc circle, then personally I can't see how it could make a difference.
Anyway - things seem to be improving so that's good.
Cheers
Ian