Quote Originally Posted by Robin Hewitt View Post
Hi Rick

AH! Confidence truly is that feeling you get just before you understand the problem :heehee:

.001mm is one micron. Standard ball nuts give you 50 microns, shimmed gives you 20, the only way to get 1 is to use double nuts and spring them. Helps if you can hold the screws in tension with more springs. The Belleville washer is your friend. You can compensate for backlash, but you will forever expect the tool to dig in.

Ball nuts bed in, they may feel firm but you are probably pushing against the dust seals and kidding yourself. The seals can't hold it when the tool loading kicks in.

If you bolt the column to a brick wall I would suggest a 5 micron step, 200 steps/mm is optimal for accuracy and speed. Half step is good, quarter step is vaguely credible, beyond that everything gets too springy.

Getting high accuracy is more a problem of rigidity than anything else. You can't mill to 5 microns because the tool will bend, you can't skim 10 microns, it will simply ignore you. To get 5 microns your tooling needs to cut a mirror finish. IMHO 5 microns or better has to be ground.

Good luck :naughty:

Robin
Well as I said if I aim high and do the best i can with what i have its an education and im not sure it will hurt will it. I do wish in my original post i had used the work theoretical...