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Calibration comes out incorrect
Hi everyone,  
Happy to report that everything is still working correctly. Thanks Yuriy for the tip on the CPU count. 
I have noticed an unusual quirk on the y-axis, though. When I put an indicator on the ways, zero everything out and travel, say, 0.500", everything correlates well ( indicator,  graduated dial and touchdro). If I reverse direction,  and turn into the indicator reads 0, the handwheel dial doesn't match (expected because of backlash). But,  the touchdro readout actually reads -0.004" i.e. it shows 4thou MORE travel than expected. Has anyone else encountered this? 
I confirmed that the added travel happens right after reversing direction - the dro starts moving before the indicator registers any movement.  It's a big, old, and somewhat worn mill (van norman 26), and the dro scale is located fairly close to the crossfeed screw which is a fair distance from the saddle ways (15" ish). I'm wondering if there's a bit of rocking of the saddle going on (heavy as it is...). The gibs are as tight as I feel I can make them without struggling to crank the wheels.
Also: if I reverse past zero, then change direction again and come back to zero on the dial indicator, the handwheel dial and the dro all read zero. 
The other though I had was maybe it's an alignment problem with the scale, read head and the travel. I made a few adjustments ( one side was a few thousandths high),  but it doesnt seem to change the 0.004" much at all.
Any and all suggestions are greatly appreciated! 

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