This model is what I designed to help me calibrate the steps/mm and alignment of my printer. I found that the error on a standard 25mm cube was greater than I liked, and I'd often forget how it was aligned, so I wouldn't know if the corrrections applied to the X axis or the Y axis.
This model is 100mm in each direction, and has axis markings on each arm.
- Slice and print the model (no particular settings, but I went with at least 0.6 infill, just to try and reduce how much it could flex)
- measure each axis,
- divide 100mm by the length of each axis, to get your correction factor, to be applied to the steps/mm for that axis.
- Check the alignment of the axes against a set square. if they are not at 90Â°, you need to check the alignment of your rails, and adjust accordingly
My first test with this print had X=99.7mm, Y=100.02mm, Z=100.00mm. Pretty close, I'd aim for no more than 1/1000 error (i.e. 99.9-100.1mm). For the angular alignment of the axes, my XY was spot on, but XZ and YZ were both off by about 1mm over the 100mm span; should aim for less than 0.5mm over the 100mm span.