The openscad model is *mostly* parametric - there are still some hard values in there and I was tired of messing around and decided to release it as-is.

Use bracketYZ for measuring both Y and Z movement. bracketX for the X dimension.

I use 6-32 nuts and bolts for securing both the indicator as well as the bar clamp. I found that a wingnut actually works better and allows you to get more clamping force on the bar than the captured nut does... ymmv

Get cracking and get your steps/mm accurately calibrated!

Notes:

This is also useful for measuring backlash.

To eliminate any effect of backlash on your initial reading make sure to make one movement after a direction change before zeroing your indicator. Ex: make a back movement, then a forward movement. Zero indicator, and measure the next forward movement.

To measure backlash: make a forward movement, set the indicator to zero, then make a backward movement, you'll see the difference if you've already dialed in a non-backlash-inducing movement.