I am experiencing some strange extrusion problems in the last two days.
My setup: P1S with AMS (Hydra Pro Mod).
1100h Print time
0.4mm hardened steel nozzle, stainless steel extruder gear (gear has been used for about 200h)
Filament: PLA (Bambu matt, Recyclingfabrik, DasFilament) 30-35% humidity in AMS
0,2mm layer hight, top glas and front door open
The beginning of the print looks normal. Perimeter is printed ok. During the filling of the first layer the filament flow stops. When the second layer is started, perimeter is printed with no problem, during the filling of the second layer the filament flow stops again.
Extruder is still spinning. no clicking sounds from skipping gears. no grindmarks from slipping gears on the filament.
howe I tried to fix the problem:
resliced the model
cold pull
used different filament
replaced nozzle with 0,4mm stainless
opend the extruder (everything is spinning freely, no dirt in housing, extruder gear teeth clean)
checked that all the connectors are seated / the fans are spinning
when I print a small moddel (3x5 cm) it just prints fine. On larger moddels I encounter this strange behavior. My guess is that the layer-time (or something connected to that) is influencing if the filament is extruded or not.
Double-check you heatsink fan, because that really looks to me like heat-creep (the heat from the hotend “creeping” up, and causing the filament to become soft in the throat, which binds it up and causes a blockage).
Because your print is starting off “good”, and then peters-out, it is the most likely cause IMO.
First thing to try, set your part-cooling fan to 100% from layer 1 (this will add a bit of cooling air-flow), and also drop your temp 10C… see if the print “lasts longer”.
dose not really look like heatcreep on the picture to me. but looks are not everything, I know.
but reducing the temp by 10°C improved the situation. I was able to print about the double of the area, before the extrusion started to fail.
I will install the other 0,4mm nozzle and test again. maybee even lower temp.
First off, Kudos to you for doing a first layer test. If I had a dollar for every time someone posted here after wasting half a spool when 0.2g of filament and five minute print would have displayed anomalous behavior.
Unless I missed it in your post. You did not say whether or not you ran a test using a direct spool feed without any intervening 3rd party hardware. From what I see here, it looks like your filament has gotten choked at high speeds which is why you would see the problem in a larger first layer test but not on the smaller test as the filament has not gotten up to max flow/max velocity.
The first culprit I would look at was the AMS and Hydra mod. Remove that from the equation first. Then test your printer in single-spool-only mode. Then work backward from there adding each new element one at a time, AMS first, Hydra second and so on.
The second thing I did not see was whether or not you tried to manually calibrate your filament. Although I do not necessarily believe it will correct your problem, putting faith in the factory defaults has been more than one person’s downfall on this forum.
last night, after checking all the fans and having a light improvment after lowering the temp, I installed a completely fresh hotend (0,4mm nozzle).
That did the trick.
Looks like, for the first swap I replaced a bad hotend with another bad hotend.
The print finished without any problems. (except the orange bleeding into the white for some reason, but thats something tomorrow-me will have a look at)
