Adding an inexpensive DRO to the mini mill

Started with the X-axis, went through a couple of designs, this worked out best with out reducing the 9.065 total travel. Ended up with tapping 1 hole in the Y-axis carrier. Indicator travels, slide stationary.




This is the only hole I tapped in the mill.



Next was the Z-axis, 7.675 travel, probably the easiest one:

Yea, I know, only one attaching bolt, but a very tight fit in the keyway keeps it solid. If it starts moving around at a later date, I can always tap a second bolt in. Indicator fixed, slide travels





Last was the Y-axis, 3.750 travel, tricky to get required clearances, indicator travels, slide fixed.




Belt conversion:


Limitations of the mini mill:

Not a lot of travel.

Hard to get X-axis gibs adjusted tight enough to obtain desired results and still be able to run power drive at slower settings. Y-axis gibs not very long, again contributing to adjustment difficulties.

Z-axis large amount of backlash, mostly due to rack and pinion instead of leadscrew design.

Other then the obvious limitations of an inexpensive mini, I think it will work out.
I have about $250 for the mill, $175 for the power drive, $175 for the belt conversion, $100 for the 3 DRO's, and about 40 hrs shop time into it.

Update: leaving the X-Axis leadscrew nut loose enough to allow about a half a turn of backlash actually helps the situation, allowing for tighter gibs. Go figure. Maybe the Nut/ Leadscrew alignment needs looking into.

Update: tore it down (again). Got it back together last night (11/12/08)very smooth this time, not hardly any backlash and will run at Sloooowwwww feed