In preparation of doing acrylic etching, I decided to finally do a skimp cut to level My wasteboard. What an eye opener. No more grid :).
Two major things came to light.
The wasteboard had shallow spots. In other words, it simply wasn’t as flat as I thought it was. My bit would grind out .001 of of in some areas and not touch others. Not at any side or edge exactly but in the middle and at another spot. Looked and felt level but when I saw what was happening it became obvious it simply wasn’t. Had nothing to do with the level of my axis.
My X axis was twisted. Yep TWISTED. This is the new solid one. It was consistently carving a slight Ridge when doing the X skim cut. I was able to verify this with a square and managed to work out the twist by loosening the bolts in the brackets and using a pipe wrench to slightly counter the twist. Then tighten everything up. Such a dramatic improvement!
I suggest that people try this if they are really concerned about accuracy. I finally have a wasteboard that I can feel much more assured is level (at least in respects to the spindle).