Can't cut accurate circles - Any Ideas what to try next?

[machinehop5]

...knot sure how UCCNC Exact stop works or is coded but, have you tried it?...most of the time high feed rates can give unpredictable results if, not under the control of an error/lag factor.
Linuxcnc uses a G64P.xxx code for Path Blending or a G61 for exact stop
G64 P0.015 (set path following to be within 0.015 of the actual path)
https://linuxcnc.org/docs/html/gcode...html#gcode:g61

Good luck hunting,
DJ

[turbotoys]

When I did the auto tune function on my Y -axis it always failed at 95% - so I just loaded the tune from my other axis being it was a close match and that is what the engineers at clearpath suggested to do. A few days ago I noticed when the axis was waiting for the next command that I could actually move the axis a little bit back and forth - it was a bit spongy.

Today the engineers from clearpath did a manual tune for me via screen sharing and dialed the motor in - they got rid of the sponginess . Now my machine can cut a circle that actually looks like one.

[Dean448]

So your using clearpath servos, which I don’t think was mentioned. They behave very different from a stepper based system. Steppers tend to lock into a position until you over power them…then they jerk to a new position, which is the opposite to spongy. Steppers are open loop vs a servo that always tries to achieve position.

What’s weird is how did the servos see any forces when your just driving a pen? The system must have been badly out of tune.
Good you got it straightened out.


Sent from my iPhone using Tapatalk

[RCaffin]

Maybe a lot of drag on the axes and little gain on the feedback?

Cheers
Roger