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LoadCell issue (MK4) ?  

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scorpizz
(@scorpizz)
Member
LoadCell issue (MK4) ?

I'm having a problem with the loadcell on the Prusa MK4 Kit.
The problem is only when doing homing on the Z-axis.

If the drag on the filament is a tiny bit more than nothing (compared with, when the filament is on top of the printer on the stand, that comes with the kit), then the z-carriage never make it to the bed surface.
It will retry a couple of times and then reset half way down. After this it end up in a red error screen and beeping. (homing error Z)
This means that running the filament through a PTFE tube or from a stand beside the printer, is out of the question because the "drag" will be too high (not that I can feel that when pulling the filament - but apparently enough).
There is no problem after homing is done. Bed leveling and printing is working as expected.
Loadcell calibration / diagnostics has no errors.

Does anyone else see this issue - is it only this printer or is there a general issue (hardware or firmware) that needs to be taken care of ?
I have sent an email a week ago to Prusa support, but unfortunately I haven't heard from them yet.

Firmware ver. 5.0.0.0+12061
Loadcell value, standby w. filament loaded = 12258
Loadcell value, touching (gently) the filament or the extruder housing = 13443

Posted : 30/10/2023 5:11 pm
scorpizz
(@scorpizz)
Member
Topic starter answered:
RE: LoadCell issue (MK4) ?

Got an answer back from Prusa today...
The issue has been seen before and the only way around it is to unwind a bit of filament before homing (give the filament some slack) to ease the resistance from the spool.

 

Posted : 31/10/2023 11:26 am
Marcelismus
(@marcelismus)
Active Member
RE: LoadCell issue (MK4) ?

I had a similar problems before. What helps: Connect a PTFE (length from about the roller to the furthest point at 0) - since then I have had no more problems.

Posted : 03/11/2023 12:06 pm
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