Extruder leaking filament
This has probably already been posted before but my pretty new mk4's extruder leaks filament, causing stringing and dots of material on the bed when making the digital heat map.
RE: Extruder leaking filament
I came here looking for a solution to the same problem.
I guess I'll just change the temperature of the hotend before the z probe in the gcode.
RE: Extruder leaking filament
Are you saying that filament continues to come out the nozzle when it shouldn't? If so, we refer to that as ooze. This are many posts discussing this problem, but it normally involves excessive hot end temperatures for the offending filament and/or wet filament. There are other cause but these two are the big ones in my opinion.
If you are saying that filament is leaking from above the nozzle that's a different story.
RE:
Filament oozes out of the nozzle during bed probing, and it leaves little dots on the bed. This transfers to the print. I'm attaching a photo where you can see little dots on the print in a perfect grid.
I was able to work around this by setting the hotend temperature very low (maybe 140°) before the bed leveling Gcode command is sent. I don't recall what the default is for the Mk4 profile, but it causes oozing with every filament I've used, including two kinds of Prusament PLA, and one spool of Prusament PETG (which didn't matter as much due to the textured bed).
I assumed this was a normal thing for an Mk4 and there is some technique to scrape the bed after leveling but before the print. If depositing plastic dots during bed leveling is not normal, I wonder if this might be related to the stringing thread, which sounds like the hotend thermistor is reporting temperatures lower than actual.
RE:
Thanks for giving me the term for this. There are indeed a lot of threads about oozing during the mesh probe!
It looks like lowering the temperature of the hotend in gcode before bed levelling is a common thing to do, so I guess I figured it out all by myself 🙂
RE: Extruder leaking filament
I don't think that this is normal. Bed leveling is done at 175C, and at that temperature the nozzle shouldn't be oozing for either PLA or PETG. I had significant PETG oozing on my MK3S, but none at all on my MK4. I wonder if your hotend assembly is faulty and the nozzle is hotter than it's supposed to be.
RE: Extruder leaking filament
It is not normal.
In my case the nozzle oozing was present on both the MK3 and MK4. The difference for me is on the MK4, the oozing interferes with the BML because of the lower nozzle temperature, where some plastics are not soft enough to be pressed out of the way. Any amount of plastic on nozzle tip interferes with this process, and adds a bias to the probing values. This error is added to the uncertainly that already exist based on the build surface roughness. On my textured sheets I have to add about -.025 to my offset after the probe and before the print to get good result.
The most significant cause of oozing, by a significant margin, is wet filament. In the winter months where I live, a dry box is an absolute requirement. With the dry box, I have zero oozing.
RE: Extruder leaking filament
@lynn, I'll take your word for it, in terms of how wet filament performs. My filament is always in a dry box (even while printing), and I keep the humidity below 10%. The 3D printer equivalent of "keep your powder dry" is "keep your filament dry".
RE: Extruder leaking filament
I have to turn it down to 145 to prevent oozing, regardless of the filament, even if it's right out of the vacuum pack. It's normally between 7% and 30% relative humidity here: I had a spool of PLA at work that we accidentally left out for 2 years during lockdown, and it was fine.
I guess I'll reach out to support about getting the XL thermistor, which seems to be solving the stringing issue I'm also experiencing. Not looking forward to creating a bunch of new filament profiles, though. Heh.
I don't think that this is normal. Bed leveling is done at 175C, and at that temperature the nozzle shouldn't be oozing for either PLA or PETG. I had significant PETG oozing on my MK3S, but none at all on my MK4. I wonder if your hotend assembly is faulty and the nozzle is hotter than it's supposed to be.