Dimensions of cut parts are way off

After going through the process of understanding the spoil board vs anchor heights as well as setting the work piece height (correctly now I believe), I ran another Find Anchors. But, my first cut has dimensional issues.

My part should be 503.4mm wide, but it is 497mm. The other dimension should be 301 but is 294.5. Some of the straight cuts seem to wander near the end of the cut. This basically means that the case I’m building will not work and I’ve wasted material.

What level of accuracy should I be expecting? What could be causing this? I’ve got my feed speed set to 1200mm/s, is that too fast for 1/8" bit? I really would like this to machine to work so I can build some important stuff, but so far, the results have not been usable. Quite frustrating, I’m now considering if I can afford a traditional CNC large enough to run the parts I need to run. Help?

how well does it move if you run the same job with no bit? (or with Z home set high enough that it never cuts)

It seems to move great, other than some slight tipping when moving in the “up” or “top” direction. I don’t see anything in it’s movement that would indicate anything strange going on.