Silk PLA causes repeating clogging during printing
This Issue is plaguing me since around a year, everytime I try to print with Silk PLA (I have two different Silk PLAs, both exhibiting this behavior), after some time (usually around layer 3) I get hefty clogging.
Things that I tested so far
- e-steps
- temperature (190°C)
- retraction (0.5mm)
- extruder tension (minimal)
- enclosure (open for better cooling, to prevent potential heat creep)
- new hotend (Mosqito Magnum -> Rapido HF)
- ensuring that there is no tangling in the spool
- flowrate limiting (everything between 40mm³/s down to 1mm³/s)
- print speed (200mm/s down to 10mm/s)
- Bed temperature (70°C -> 60°C)
I never have these clogging issues while printing PETG, Non-Silk PLA or ASA. Even helping the extruder manually by applying pressure to the stepper gear doesn't alleviate the clogging immediately. With some perseverance it will start printing ok again for a few layers, then start clogging again. obviously, this is not a good thing because due to the clogging, the entire parts stability is catastrophic in the end.
22 Replies
I have just completely dissassembled my extruder, the bearings for the two extruder gears seemed a bit hard to turn. I don't believe that this could cuase issues but better safe than sorry
reassembled (phew, that lgx has more parts than I anticipated.) Also checked if the rods are bent but they appear to be fine. Lets see if re-oiling the bearings helped. The amount of dirt and gunk that poured out after oiling makes me hope that this whole issue was basically just the lgx gears binding due to residue in the bearings
it looks like you've addressed everything except maybe the nozzle temperature is too low. Silk filaments tend to prefer higher temps. I'm currently printing with some cc3d gold silk filament. I set the max linear print speeds for everything down to no more than 50mm/s and volumetric flow of 10 mm^s/s. Backing up, I started with flow calibration, then a temperature tower (220 was best for this filament) then teaching tech's flow calibration which very clearly gave out at 60mm/s.
I also recommend confirming your max speed by looking at the nozzle print speed view after slicing. If the scale goes above your intended max, there are more slicer settings to tweak
yeah but the speed is definitely not the issue. I had clogging at 10mm/s max speed. It does however seem that cleaning up the extruder did actually make a difference. The Issue is not gone but MUCH better
i only point it out because i went through this myself within the last 24 hours. There are tons of speed limits in prusaslicer and I had to turn them all down
the speed at the end is printed without any issue
the very next layer it is extruder clacking
the layer after that it works flawlessly
that looks faster than 50 mm/s to me
it is
but as said, the clogging also happens at 10mm/s
the fact that it happens intermittently really pushes me to an assumption that it's some kind of mechanical thing that is maybe dependant on the orientation of the extruder gears or something and only happens when the gears are in a specific orientation
which is why I cleaned them
which actually DID help the issue, albeit not completely solve it 🤔
when i printed the flow calibration, it printed multiple layers at 60mm/s before it completely clogged.
what kind of filament?
cc3d silk gold
pla
ah so also silk
well I just halved all speeds (speed factor to 50% in the DWC) so lets see if I do not see any clogging anymore
I'm pretty certain it will still clog
lowest speed is now 12.5mm/s
(small perimeters)
hmm ok I hear occasional clacking but actually less. I might have to add that I also just switched from SuperSlicer to PrusaSlicer because I hoped that the slice quality is better with the latter (Overhangs are a catastrophe with SS)
so it's possible I was now fighting a slightly different problem. Still cleaning the bearings of the extruder seems to have brought the biggest difference
stupid hard-to-indent silk filament >.<
ok I get reliable clacking at 70mm/s
ok so I reduced the speeds now. It is now clacking at 25mm/s
correction, it is now clacking at 12.5mm/s
so it is with utmost certainty not a speed issue
also, earlier I was printing infill with 240mm/s without clacking
outside of these spurious occasions where EVERYTHIGN clacks
these ugly lines in the part have been printed at 25mm/s
as you can see at the bottom right the same speed CAN produce good results. until it doesn't
out of curiosity, what nozzle size and nozzle material are you using (e.g. brass/stainless/hardened steel)
different material nozzles heat/cool faster than others, and fan settings could be changing at different layers, causing things to consistently start failing at specific layers
fan is nailed at 100% for everything except the first layer.
I'm using a nozzleX which is nickel plated steel iirc
Try lowering retraction. I have mine at 0.2 for sunlu silk PLA. Silk PLA is incredibly gummy, so it sounds like your retraction is too high and it is eventually causing a clog
I just redid retraction, if I go below 0.5mm I have stringing
tested from 0.2mm in 0.1mm steps
but yeah I also assumed it might be a reason, can't really go lower though
You might get stringing, but this is to test to see if it affects when you get a clog
mh
valid point
ok it's not retraction.
Set retraction to 0.2 (from 0.5) and had exactly the same issues again
I also evaluated the Fan speed, seeing that it started locking up in the first layer that has full cooling
however, I limited now cooling to 50% (against my gut feeling, I think this needs as much cooling as it can get) but it actually does not show any difference whatsoever
After drying my filament for 6 hours today and still having the issues I finally shoved a thermal probe into the hotend and it appears that the cooling is not good enough. The entry into the heatbreak is exceeding 50°C, which is too much for the silk filament to stay solid
however, I actually pointed a desk fan at the printer to reduce the temperature of the air in front of the hotend fan, to no measurable avail