DIY Spindle Square For Tramming Your Mill

[Karl_H]

When I built mine, I took an extra step to adjust one of the dial indicators so that both have the zero at the 12 o'clock position. (Actually 12 o'clock-ish position.) It makes it a bit easier to read. I trammed my mill just as you described, then adjusted the z axis so the left needle was pointing straight up. Then I loosened the set screw for the right dial indicator and moved the indicator until the right needle was straight up. I still have to do an actual calibration, but t is less confusing with both needles pointing the same way.

I am glad you didn't make a big deal about the arbor and bar being perpendicular since that doesn't really matter.

From a design perspective, you want to have the dial indicators as far apart as possible, for a more accurate reading, but close enough that you have clearance to rotate the tool 180 degrees.