.010 is not to horrible. I changed my files to where it measures each bit when it picks it up. It takes another 20 seconds or so for each tool change, but it seems to be better. Also I don't have to measure all tools after start up.
Try changing tools to pick up the next one. Then "measure" the current tool with the sw and see how close you get.
Also I got my tool measure switch straight from wincnc and not the SS one. Not sure how good the switch is from them, but if you try this test it should tell you if the tool holder is not seating the same in the spindle or if it's the switch.
You could even take the same bit and remeasure several times, comparing how well it does. I think you should be able to beat .010, but should not expect .001
It is also possible you have .010 slack in the z ball screw and that can be shimmed out.
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