Extruder skipping steps MK3S
hello.
I recently had to replace the pinda probe because there was an intermittent fault in the wiring. The change went well and the printer is working again (so I thought)
trouble is now the extruder is skipping steps and not extruding properly. It’s not skipping all the time either. Sometimes it will finish an 8hr print fine and not miss a beat.
Other times it will skip lots and then recover then skip again.
ive updated to the latest FW on the printer, I’m using the latest prusaslicer
ive adjusted the idler tension. Everything looks ok inside the idler door also.
At a loss now to where to look next.
The printer has thousands of hours of successful prints and this has only just started happening after the pinda was replaced.
if anyone has thoughts on what’s happening I would be grateful.
Jason.
RE: Extruder skipping steps MK3S
I have no idea what "extruder is skipping steps" means. A photo might help fill in the gaps in interpretation.
RE: Extruder skipping steps MK3S
skipping steps. Clicking. Not extruding the correct amount. Leading to this. (Attached)
I have slowed the printer to 90% speed and it seems to have helped. Still not sure exactly what has changed. But something has.
jason.
RE: Extruder skipping steps MK3S
Well - the slice probably has nothing to do with the problem - it appears to be strictly printer related. Also, probably not retraction heat break issues, either. Since you've dealt with wire failures, they are common as a printer gets older. And, difficult to diagnose until you get a hard fail. It is curious both under-extrusions are at the same altitude - a wire fault can happen at certain cable positions. Is this consistent or do these happen most anywhere in the build height? You might try monitoring the extruder temp using Octoprint.
But places to look for more common things that disturb extrusion are the nozzle/heat break torque. Improper assembly of the two can cause weird things to happen. Read up on the correct nozzle assembly instructions from E3D and follow them to the letter. Each step is critical. E.g., if the nozzle is bottomed out in the heater block, you've done something wrong. That spec of black plastic on the white part hints at this.
The other factor is just old plastic in the nozzle. A good set of cold pulls can help. Or extra dust in the heat break: pop out the nozzle and blast some canned air upwards to clear and filament chips that can lodge in the PTFE and upper heat break.
RE: Extruder skipping steps MK3S
The hot end has never been disassembled from the prusa factory. The skipping leading to under extension happens at random heights and other times I will get through an 8 hour print with no issues.
I tried reducing the volumetric flow to 11.5 and this also didn’t help. The 90% speed also didn’t fix it
starting to wonder if it’s a partially clogged nozzle. Some cold pills and or cleaning filaments might be needed. Or a new nozzle.
it’s the original nozzle that came with the printer in 2018. and has 2 years and thousands of hours on it. Majority is PLA and some PETG and ASA. Nothing abrasive has ever been printed with this nozzle.
might try heating it up higher and running some ASA or PETG. See if that helps. Could be some PETG OR ASA stuck in it.
I’ll keep this updated as it might help others at some stage.
jason.
RE: Extruder skipping steps MK3S
I've had PET stick in the nozzle after a filament change to PLA - it stays in there like a marble floating around.
RE: Extruder skipping steps MK3S
I’m going to try a few cold pulls and see if that removes any gunk. I’ll use some ASA as it’s the highest temp filament I have. Otherwise a new nozzle might be in order.
might give me an excuse to buy that nozzle X I’ve been wanting.
Jason.
RE: Extruder skipping steps MK3S
Here’s the results of two cold pulls using ASA.
time will tell if there is any improvement.
Jason.
RE: Extruder skipping steps MK3S
This was the first pull. Attached.
RE: Extruder skipping steps MK3S
Those do not look like clean cold pulls... you should be able to see the cone inside the nozzle.
Like this example: nozzle end on the left ...
RE: Extruder skipping steps MK3S
Prusa cold pull article
RE: Extruder skipping steps MK3S
Here’s how I did it.
heat to 260°. Load ASA. Allow to cool to room temp. Heat back to 260 while pulling the filament back out and when it got to around 170 the filament popped out.
I did that 3-4 times. They all looked the same with varying degrees of crap on them.
None looked conical at all
jason.
RE: Extruder skipping steps MK3S
I’ll try the prusa recommendation next. See if that improves anything.
thanks for the link.
Jason.
RE: Extruder skipping steps MK3S
ASA cold pulls should happen around 100C; if you set the temp too high the nozzle will zoom right past the ideal pull temp and you'll get what you are getting. Most pulls from the E3D extruder are 'stretchy' so you have to pull at a constant rate but not break the filament before the nozzle gets warm enough to release the filament. The stretch is due to the heater block being warmer than the nozzle tip ... so filament in the middle of the nozzle gets stretchy as things are warming. And I always let the nozzle drop to 35C or less before starting the heater up. Saves me extra tries.
RE: Extruder skipping steps MK3S
Here's an image of more cold pulls others have done:
RE: Extruder skipping steps MK3S
Thanks for the info. Good to know.
the top two in the pic seem similar to what I had. I’ll try it again with pla at the recommended temps from the prusa link above and see how that goes.
I will post back with results. Probably tomorrow now. Thanks again.
jason.
RE: Extruder skipping steps MK3S
Just tried the cold pull using pla and the method in the linked knowledge base above. Very similar result.
but now I have noticed it’s really hard to load filament to the gear. So I’ll have to fully disassemble the hot end. See what the issue is.
I’ll post back here after I’ve done that.
won’t be for a few days.
jason.
RE: Extruder skipping steps MK3S
I got this that I think is ASA out of the top of the hot end , the loading hole above the gears.
not 100% sure it’s fixed, but this sure wasn’t helping things.
it kinda looks like filament might have worn a grove in it so this could be a big part of the issue still haven’t done a full successful cold pull that is nozzle shaped yet.
if that white part didn’t fix it I’ll try again
jason.
RE: Extruder skipping steps MK3S
That white blob thing didn’t fix the issue.
guess I’ll try some more cold pulls. Failing that a new nozzle maybe.
Jason.
RE: Extruder skipping steps MK3S
You might try a purge, then a cold pull. Set nozzle to something high: 260 or 270, and extrude 100mm of filament (manually push it through or use TUNE to push it through). Or get some cleaning filament and run that through before setting up another cold pull.