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Extruder skipping steps MK3S  

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Jason_M
(@jason_m)
Trusted Member
Topic starter answered:
RE: Extruder skipping steps MK3S

I’m trying another cold pull or two using the explicit instructions linked to above. Hopefully that helps. Temp set at 270. Then allowing to cool. Then reheat to 85 and pull. 

I really don’t know where to go next apart from new nozzle of this doesn’t solve it. 

Posted : 09/10/2020 4:37 am
Jason_M
(@jason_m)
Trusted Member
Topic starter answered:
RE: Extruder skipping steps MK3S

Doesn’t look like the nozzle is clogged. 

Two clean cold pulls. No junk and shaped like the inside of the nozzle.

I have no idea now what to try next. 

jason. 

Posted : 09/10/2020 5:11 am
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(@)
Illustrious Member
RE: Extruder skipping steps MK3S

Well - doesn't look like the nozzle is a problem either. They wear but usually produce other issues when they wear out. So more things to try:

1) Adjust the tension on the drive gears: increase it a bit, turn the screw in a turn and see if you have more or less clicking.

2) Do the opposite: loosen the tension a bit (counter-intuitive, but... too much tension can add drag).

3) Inspect the filament path for anything that can add drag.  Like the spool hub rubbing on the edge of the holder rod, filament path routing over something rough or sharp.

4) Check the Bondtech gear set screws are snug. Also, while in there, press on the idler gear and see if it can flex (a MK3 issue - check the axle is centered in the door pins - flush on one side is not good). 

5) It isn't unheard of to have filament have a thin section once in a while.

6) And, flow changes can be caused by air flow in the room. Is there a new fan, is AC / heat on now that wasn't? Window open? 

7) ... very rare, but dust can collect in the heat break and catch the filament. Removing the nozzle and blowing air up through the system will clear the dust. I've have clouds come up.

8) And more thoughts ... lol: check the PTFE isn't fouled in the Bondtech gears ... and the PTFE does wear out over time. Again, doubtful that's the problem...

This post was modified 1 year ago 3 times by --
Posted : 09/10/2020 5:36 am
Jason_M
(@jason_m)
Trusted Member
Topic starter answered:
RE: Extruder skipping steps MK3S

Thanks for the suggestion as to what to look at next. I’ll check all of those over the weekend. 

it’s not the spool holder as I’m using a custom one that runs on bearings. Has to be somewhere inside the hot end. Possibly the ptfe tube. Or like you said the gears or dust. 

ill post what if anything I find. 
So odd that it only started after I replaced the pinda. 

and also odd that it will sometimes print 8hr job with no issues. But the next one will skip. Also it’s the same filament brand (one I use almost exclusively) ESUN PLA+

no ac or fan in the whole house. So that’s not it either. 

jason. 

Posted : 09/10/2020 6:44 am
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(@)
Illustrious Member
RE: Extruder skipping steps MK3S

The PINDA is only used for bed leveling, and it has no effect after the bed level is done. The firmware adjusts layers only so far after a cal, if you are seeing the issue a centimeter off the bed, it has nothing at all to do with bed leveling.

What might have changed is things you moved around in the EINSY box while changing the PINDA cable. Loose thermocouple? Loose heater wire? Loose power supply cable? 

One other test you could run is to try printing something tall in vase mode. See if it ever has the "skip". That might eliminate any weird infill/perimeter issues; or perhaps highlight a positional problem like a sticky bearing that randomly stalls a stepper.

 

Posted : 09/10/2020 7:51 am
Jason_M
(@jason_m)
Trusted Member
Topic starter answered:
RE: Extruder skipping steps MK3S

Yeah. I realise the pinda itself isn’t the cause. Just odd that something changed when I replaced it. 

thanks again for all the suggestions. 
ill start checking things over the weekend. 
 
I have a print going now after the cold pulls. So far no issues. But that’s no guarantee either. It’s around 8 hour total print time.if that finishes ok, I’ll do another print and see how that too does. 

if the issue still persists (as I suspect it will) I’ll have to start pulling the hot end apart and do a good inspection and clean. 

jason. 

Posted : 09/10/2020 8:05 am
Jason_M
(@jason_m)
Trusted Member
Topic starter answered:
RE: Extruder skipping steps MK3S

Little update. 

not sure exactly why, but I’m now closing in on around 25 hours print time with no skipping from the extruder after the two cold pulls. 

they looked clean though. So not sure if that was a fix or not. I’ll not be 100% confident it’s fixed till I have a lot more print time with no more skipped steps though. 

jason. 

Posted : 10/10/2020 9:48 am
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(@)
Illustrious Member
RE: Extruder skipping steps MK3S

Those pulls prior to the clean ones did not look so clean: they may have rid the nozzle and heat break of most of the garbage, and the two final pulls did the polishing. 

Regardless, every once in a while the print does weird things I can't explain - and trying to decipher the root cause is sometimes unproductive. Just too many variables. A small drop of lubricant on the filament during manufacturing that wicked out along a meter or so; a change in chemistry in that section of filament (it isn't always 100% homogenous); a draft in the room; a burr of dust in the Bondtech gears; etc. Then we as observers see associations that aren't really there and we go down rabbit holes. lol.

That is is working better now? +1

Posted : 10/10/2020 5:11 pm
Jason_M
(@jason_m)
Trusted Member
Topic starter answered:
RE: Extruder skipping steps MK3S

After around 50 hours of good printing with no more skipped steps the issue is back. 

i will order a new nozzle and or hot end and hope that fixes it. 

jason. 

Posted : 13/10/2020 4:38 am
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