I needed some brackets to hold a dial indicator in place for measuring the travel distance for all three axes on my Prusa. And I didn't want to have to remove the extruder or anything like that.

This simple set of parts should solve that problem for all of us.

This set may work on Mendel and other similar builds.

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.