Help needed

[AndyUK]

Peter, If it is cutting squarely on the X-Y plane, then the easiest thing to do is put an MDF sacrificial bed on and machine it flat with a largish cutter. IF that produces a rippled surface, then your Z axis is not going squarely up and down, again geometry!

Can we deviate slightly from topic and discuss this? As a rather inexperienced user, I'd have thought that ripples here would indicate that the spindle isn't trammed - I wouldn't have thought a misaligned Z axis will show when the cut is at a constant Z.

[cropwell]

Can we deviate slightly from topic and discuss this? As a rather inexperienced user, I'd have thought that ripples here would indicate that the spindle isn't trammed - I wouldn't have thought a misaligned Z axis will show when the cut is at a constant Z.

If the cutter face isn't square to the bed, when you cut it will do an angled cut. The larger diameter cutter you use, the more the effect. This will make a sawtooth wave ripple on the bed and it is quite noticeable. the distance between the ridges will depend on stepover. I am assuming that you use a raster or spiral pattern, trochoidal will be less noticeable.

This error will also be noticed on the side walls of a deep cut.