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fralgome
(@fralgome)
Active Member
DEFAULT_AXIS_STEPS_PER_UNIT

Hello, although I can print well, I want to solve a doubt:

Why the DEFAULT_AXIS_STEPS_PER_UNIT for Z-axe is 3200/8 (=400), if at TMC2130_USTEPS_Z it is declared as 16 microsteps; so, 200 steps/rev *16 microsteps divided by the pitch of leadscrew (2 mm) should be 3200/2 (=1600)

Regards.

Posted : 29/04/2019 5:47 pm
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(@)
Illustrious Member
RE: DEFAULT_AXIS_STEPS_PER_UNIT

Are you sure the lead screw pitch is 2 mm? Measure your screw pitch and let me know.

Posted : 29/04/2019 6:01 pm
fralgome
(@fralgome)
Active Member
Topic starter answered:
RE: DEFAULT_AXIS_STEPS_PER_UNIT
Posted : 30/04/2019 1:59 am
fralgome
(@fralgome)
Active Member
Topic starter answered:
RE: DEFAULT_AXIS_STEPS_PER_UNIT

According to this, although the "pitch" of the lead screw is 2 mm (T8-2), due it has 4 starts the "lead" (axial advance per revolution) should be 2*4= 8 mm.

Posted : 30/04/2019 2:10 am
fralgome
(@fralgome)
Active Member
Topic starter answered:
RE: DEFAULT_AXIS_STEPS_PER_UNIT

But now I have another issue (that also fits in this topic).

I used GT2-20 pulley for both X and Y axes, so due the 20 teeth pulley, I changed DEFAULT_AXIS_STEPS_PER_UNIT from 100 to 80 and everything goes OK except for the "4-points calibration" of the XYZ Calibration:

  1. During bed calibration point 1 of 4, the PINDA finds the calibration circle well
  2. But at bed calibration point 2 of 4, the X-carriage goes too far to the right (in fact hit the x-end idler) and thus start looking for the calibration circle at wrong location, failing at that point.

Now, I am sure that this fail (X-carriage goes too far to the right) is related to GT2-20 pulley (their steps per unit), because I printed a 16 teeth pulley on PLA and the 4-points calibration finished more or less fine. Of course, I used that printed pulley just to confirm that the 4-points calibration do not use the DEFAULT_AXIS_STEPS_PER_UNIT

In short, does anyone know in which part of the firmware should I adjust the steps per unit for the 4-points calibration routine?

Thanks in advance.

Posted : 30/04/2019 2:50 am
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(@)
Illustrious Member
RE: DEFAULT_AXIS_STEPS_PER_UNIT

Yep - the calibration is for a standard gear ... you'll need to modify that routine to correct for the odd gear you chose to use.

So I take it this isn't a Prusa printer...

Posted : 30/04/2019 3:36 am
fralgome
(@fralgome)
Active Member
Topic starter answered:
RE: DEFAULT_AXIS_STEPS_PER_UNIT

I am sorry. Perhaps I should have started since the beginning; my name is Francisco and I'm from Mexico.

Since long ago (2010), I've been following (and building) through RepRap movement some Prusa's developments like the Prusa-Mendel, Prusa i2 and i3; So when I saw what Prusa MK3 can do, I definitively needed to build one of those. So I started to source the parts from some vendors in Mexico.

After printing the parts and getting the vitamins, I assembled the MK3 and try to make it work, and although everything is ok (the machine is actually printing with a very good precision), I had the "Calibration problem" that I exposed here (and although it does not really affect the performance of the printer), I could not solve it myself after trying it for all the day, and I need some help. Anyway tomorrow I will review the mesh_bed_calibration. h and mesh_bed_calibration. cpp to try to find the steps per mm used.

Regards

Posted : 30/04/2019 6:18 am
fralgome
(@fralgome)
Active Member
Topic starter answered:
RE: DEFAULT_AXIS_STEPS_PER_UNIT

awesome precision

Posted : 30/04/2019 6:46 am
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