Other source of imprecision while using default UM3 profiles is that because it uses so low jerk, it creates extra amounts of extrusion due the slow speed when changing directions.
You can edit that on advanced mode if you unhide the options bu default.
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Also to change steps values on UM3 you don't need to build your firmware. You would need to activate Dev Mode, logging by ssh to your machine IP (ssh root@ipaddress password ultimakwr) and then find the jedi.json on the share/usr/griffin/griffin/machines) and then edit the text file using vi editor). Ofc all this if done wrong can brick your machine (not super dangerous but just a warning about changing values).Edited by Guest
You cannot set "current STEPS" without compiling your own firmware. But the good news is: you don't need to. What this person has done is very strange IMHO. The XY values should be 80. He is adjusting an offset with a gain. I bet that when he prints a calibration unit half the size, he would arrive at different values.
The XY resolution is determined by the stepper motors and the belts/pulleys. They are exactly 12.5microns/step (thus 80 steps/mm).
The 0.3-0.4mm offset that you measure comes from inaccuracies in the printing process. One example is the "elephant foot".
Another example is that holes are always printed a little smaller than designed in CAD. Due to various causes (search the forum).
Do you use Ultimaker filament? If not, you might need to tweak the print settings to get optimal results.
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