Strange Wave Patterns

[insta]

I stickied your thread, Ed.

[pyronaught]

It looks like Z height was the issue. I know I tried different heights, but sometimes when I tighten the stop nut back down it spins the stop bolt right back to where it was before I changed it. Jims knob tweak on-the-fly worked well for verifying it was a Z height problem though. This part in the picture is really warp prone at the corners so I was trying to use the lowest possible Z height I could get away with to help hold it down. I guess there must be this tiny zone just above "astro turf" where you get waves, I've just never seen it before.