I've built a DIY PCB mill and I'm using a HobbyCNC Pro rev1 (I think) driver. I've installed the LinuxCNC Distro and have done the latency testing to get my appropriate values. I am having issues with my steppers skipping steps. I've run several small PCBs, and I always have the issue with my boards getting way off track in a short time, especially when milling the elipses for IC pins.
I can visually see as well as feel the leadscrews skip a step (or more likely quite a few) when an axis is ramping up or ramping down from max speed. It is likely missing more than this, but this is the only time it is noticeable. I am using 60oz.in. Applied Motion Products - 44A501711-001 unipolar stepper motor steppers with 200 steps per rotation from alltronics. I have the wiring correct on these for the motor drive I am using. The motor driver is tuned to those motors as well.
I am hoping someone might be able to take a look at my settings and spot something I am missing. My settings for the EMC2 stepper mill configuration wizard are below. The same values are used for all 3 axis.
5000ns Step time and Step Space
Dir hold and Dir setup = 20000ns
Base period Max Jitter = 18323
MIn base period 33323
max step rate 30009
Motor steps = 200 steps per revolution
No microstepping, so that field is left as 1.0 (Motor driver is set up the same)
Motor : Leadscrew = 1:1
leadscrew pitch = 20 rev/in (standard 20TPI all thread rod with DIY anti-backlash nuts. Don't bother lecturing me on using allthread, I can't afford anything else ATM.)
Max velocity = 0.25in/s
Max acceleration 1.0 in/ S^2
I attempted to reduce the velocity and acceleration values, but this actually made the problem worse. Any help would be greatly appreciated!