My MPCNC is pretty much complete and I have been doing some test cuts. TO start with, I leveled my spoilboard and then skimmed cut some redwood to create a smooth surface. I am using a 1" cutter. The result is leaving a ridged finish. Is this more likely the Z axis not being perpendicular to the XY planes or is it the size of the cutter causing deflections? Is there a way to tram the Z axis?
Well, two things here. your Z axis should be correct, check with the best square you have and takes a careful eye while assembling and tensioning your gantry. But is typically very easy.
The other is the tool mounting itself, also typically very easy but can be shimmed with a piece of tape or two on the mount points.
A 1" bit is giant, very large for this type of machine. To have that type of accuracy is a whole new level of careful eye. I have a tool on thingiverse and using it can easily get really close.