Quote Originally Posted by Lee Roberts View Post
Could give a single flute cutter a try as well, plastic melts when it gets hot, the less chip re-cutting the better, although that counts when your cutting deeper into the material i.e pockets and stuff like that it could help here to,.

Keep an eye on your chip loads as well, when they get to low you start to see rubbing rather than cutting.
Correct! I had a look at the feathered strips that came off the material, and they were kind of stuck together.

Quote Originally Posted by Voicecoil View Post
Because if you hadn't had a good skimming before I was going to suggest a very similar prognosis to the one you've just come up with! Though it might be more than a matter of the rails being bowed - obviously they're less stiff in the middle than at the edges, so the spindle can move about more.
Thankfully, the rails weren't bowed. It was the plastic cut that was throwing me off. The bad areas must have been where the plastic was melting or something. I added a piece of wood on top and surfaced that. Much much better.

Quote Originally Posted by Lee Roberts View Post
Personally I thought at first that the spindle wasn't quite perpendicular to the bed and needs minute adjustment. It looks to be spot on when going in what ever the directions are to the left and right of the pic (top to bottom of pic), whereas you can see tiny lines/ridges on the cuts that go from left to right of the pic (the problem areas).
Correct again. My left to right adjustment during tramming was off. Its spot on now. The front to back (tilt) needs a 0.1mm shim, but i've got it really close. I can see the vertical lines in wood, but hardly feel them. I can't see horizontal lines at all.

Only problem now is my gantry still isn't perpendicular to my y axis, so cutting a rectangle of 50.1mm x 40.1mm gives me a diagonal of 63.8mm instead of 64.2 mm. However, both diagonals are identical.....weird