pn2
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Live Z increases with every print

Nov 10, 2018 2:35 pm

I think I ran into a bug, or at least this is how it looks to me.

With every print from SD card, the live Z value increases massively. It looks like the original value (which was around -0.7) is added on top of the previous value every time. So the next "correct" live Z would be -1.4, then -2.1 etc.

This definitely was not the case from the beginning, my live Z values were stable.

Any idea how I could fix this?

I have a relatively new MK2/S and use Slic3r PE.

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RHDreambox
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Re: Live Z increases with every print

Nov 11, 2018 10:04 am

Check your PINDA sensor. It may be loose.
Happy owner of a Prusa MK3

pn2
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Re: Live Z increases with every print

Nov 11, 2018 4:15 pm

The PINDA is fine, and after a cold reset the values are fine again (but then start again to increase from print to print).

It seems that I am not the only one experiencing this: general-discussion-announcements-and-re ... 25752.html

tim.m9
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Re: Live Z increases with every print

Nov 11, 2018 5:13 pm

I had the same problem.
Somehow I had lost the Z calibration by doing something when I first started using my printer.
If you run the Z calibration procedure (up to the top, rattle, etc), you must then run the V2CalibrationZigzag using PLA. It is at the end of this routine that a value is stored to non-volatile memory. Unless this value is stored, I got the same situation that you are getting now.

I do not know if it is an offset value that is stored or merely a flag to say that Z is now calibrated, but you have to do it.

That is what Bill Campbell was telling you in the other thread.

I have no idea how this is or isn't connected to Octoprint.

Nevertheless, it is easy, quick and painless to run the V2Calibration routine, it is stored in the machine and accessed from the front LCD panel now.
Worth trying.

david.t28
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Re: Live Z increases with every print

Nov 12, 2018 3:41 am

What was your Firmware version. You may want to compare all software versions in case the issue is being caused by lets say the Slic3r version and MK3 firmware version.

pn2
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Re: Live Z increases with every print

Nov 14, 2018 6:18 pm

What was your Firmware version
Firmware is 3.1.0

I have re-run the calibration V2 after running the setup wizard, and for the moment things look fine.

However, I had run the V2 calib. after assembling the printer. If indeed something special was stored during this routine (except a flag that it was run), then it was definitely lost or altered later, which should not have happened IMO.

Also, I really would like to understand what that setting would be. My understanding is that the steppers run the carriage into the end switches to determine the home (zero) position for the X and Y axis, and that the PINDA probe sets the zero positon for the Z axis.
To this Z zero position (which really is the interpolated bed plane) the live Z offset is added during printing.

What additional settings could there be that "break" this referencing in X/Y/Z space?

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BillCampbell
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Re: Live Z increases with every print

Nov 15, 2018 6:55 pm

Again confusion between different unrelated settings.

Z offset is a number you enter in Slic3r settings and is used to compensate the difference in Z height needed for different types of filament without altering live Z setting.

Live Z as I said before is a measurement specific to your printer, that is only stored into EEPROM when the machine state has been set to tell it to record changes. It is the most important calibration of all in regard to filament adhesion to the bed.

The PINDA is not checking height, it is mapping bed level variances.
Bill
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Founder member of Philippines Prusa Printer Owners FB Group
Sponsor Pillars of God Academy in Bacoor

pn2
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Re: Live Z increases with every print

Nov 16, 2018 6:24 am

Again confusion between different unrelated settings.
Actually, no.

I did only refer to the live Z that is made with the rotary knob while printing. I have not made any adjustment in Slic3R, nor did I refer to these.
Live Z as I said before is a measurement specific to your printer, that is only stored into EEPROM when the machine state has been set to tell it to record changes. It is the most important calibration of all in regard to filament adhesion to the bed.
I think nobody disagrees about this.
The PINDA is not checking height, it is mapping bed level variances.
It depends on what you mean with "height" (I did not use this word).

In addition to measuring bed unevenness, I think iit also is used to home the Z axis (which has no mechanical end switch). In that sense it also sets the origin of the Z axis. Therefore, in absolute terms, it sets some "height offset" (in the sense of an absolute mechanical position on the Z axis).

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