3D carving errors query

[marbles]

Howdy,

I’m still finding errors in my 3d carvings. Just occasionally as in this rotary carving I have a line or a band which I need to isolate and go back over to correct. Sometimes as in this test example they are so slight I don’t notice till i’ve removed.



The error is always from the z axis and the problem accelerates the higher and faster the elevation changes are, in relation to the distance between peaks and troughs. I can usually resolve the issue by repeating a pass over the area but think its time to understand the main issue and deal with that.

Material: Beech
head height approx 75mm
Finishing pass: 0.5mm taper ballend, 60mm/s, plunge 30mm/s

I’m presuming this is a mechanical electrical problem as I built the machine from scratch and not a gcode issue. I’m also wondering whether I run the machine too fast. Perhaps I need to adjust the velocity and acceleration of of the z axis motor in Mach 3 motor tuning. Perhaps a combination of severe things?

z axis
1:1 ratio. steps per 169-ish, Velocity 5000, Acceleration 500

What i’m sure would be useful would be if machine could slow to accommodate abrupt Z axis changes and speed up over longer curves, similar to deceleration for tight corners on flat material.

Any ideas or suggestions welcome.