So I’ve gone through and surfaced my baseplate, noticing there are some pretty big ridges between the passes.
Next I’m using a 1-2-3 block to inspect Z axis alignment. I found my nod to be .011" variance across 3" which is super off, which seems to validate why I got the ridges. With my dial indicator at the top of the block moving down, the dial turns clockwise, so for this does this mean I should actually remove the top shims and reshim the bottom bearing blocks against the cast carriage?
Earlier the online calculator recommended I use 4 shims per bearing block in the upper position.
Also, since the ball screw goes through the carriage, is it possible to add/remove shims without removing the x axis ball screw?
A few of us have had to adjust shims because the calculations were way off. You can add and remove shims without removing the ball screw though, which is handy.
Yes, reshim at the bottom. The calculator works for some folks, not for others. I reshimmed to get the z axis square to the side of 123 block, then when I properly trammed the spindle i had an issue with it being out in both the x and the y directions by 8 or 9 thou across 6". X is easy to fix, you just loosen the spindle mount bolts where it meets the carriage it rides in and push back and forth to get it right. Y is a different story. I had to cut up shims and put them between the bottom of the spindle and the carriage (not at the linear bearings where you originally set the Z travel error).
When i was done, i had less than .002" error across 16" of tramming distance all the way around. Plenty good for me. The problem, however, is that i did this at the upper spindle location where I intend to leave it. I wanted to resurface the base plate one more time, so I left it high and used a 5 or 6 inch long endmill to do it. If you go that route, take very little off the plate (.001" or so) and slow the ipm’s down, those long endmills will chatter even in aluminum. Make sure you use a carbide mill, as well.
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