STEP Calibration Piece (X, Y and Z axis)

To get dimensionally accurate printouts the printer has to be calibrated appropriately. I found that my Ultimaker had some issues reproducing technical models accurately leading to issues with fit of screw holes, etc.

This calibration piece allows to adjust the X,Y and Z-STEPS appropriately.

Just print this piece and then carefully measure the 3 sides with a Caliper. Make sure you don't include the first layers as they usually come out slightly wider.

The calibration object is 100mm on X and Y axis and 50mm on the Z-Axis.

You can then calibrate your STEPS using this formula:

X,Y-Axis: 100 / [measured length in mm] * [current STEPS]
Z-Axis: X,Y-Axis: 50 / [measured height in mm] * [current STEPS]

For example my X Axis X-STEPS were 78.4 and I measured the side to be 99.27:
100/99.27 * 78.4 = 78.97
I repeated this for all Axis.

You then can set these values either in the printer itself, or in my case I compiled my MARLIN firmware myself and configured it right in the source code in "Configuration/h":
`#define DEFAULT_AXIS_STEPS_PER_UNIT {78.97,79.26,535.44,760*1.1} // default steps per unit for Ultimaker`

After a second print with the new settings my object measured a correct 100.07 x 100.05 x 50.02mm.

Be aware that PLA and ABS loose volume when cooling at different ratios. So that calibration will only be 100% accurate for the material you have done it for. ABS typically has a shrinkage ratio of 0.5% to 0.9%…