Ridges in 3D profiles = hair loss and lots sandpaper

[Shinobiwan]

Hey folks

I've got some weirdness going on with the machine and 3D profiling.

Take a look at this:



The arrows show the tool path direction along the profile. What I'm getting are ridges that run perpendicular to the step over (ie. if you step over top to bottom, the ridges run left to right). Just to be clear this isn't a step over ridge I'm talking about and something else is going off here.

What could be causing this sort of thing?

I can say this -

• The pattern is consistent and almost looks part of the g-code?
• It doesn't matter which axis you step over in X or Y.
• Also doesn't matter what the profile shape is or the angles involved.
• Its speed independent I've tried 1m/min upto 10m/min and nothing changes.
• I'm using Mach v3.43.66 with Solidcam.

My first first I thought I might have some backlash somewhere but the pattern is very consistent even over a large area with many hundreds of step over passes. I've also ruled out loosing steps as the overall finish piece is as intended and doesn't deviate from the original model. Lost steps would normally be very easy to spot by the end of a large 3D job. No problem with that here.

Hope someone can help.

Ps. There's no jerky movements and machine is smooth whilst running the 3D profile as shown in this vid: