Is Prusament Mystic Brown clogging the nozzle at low speeds?  

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

Can anyone confirm this problem?

I can confirm with Prusament Vanilla White PLA. Low speed appears to be the consistent factor. I had two Benchy boats fail at exactly the same point with extruder jams (PLA at wider diameter in heatbreak beneath PTFE tube). The prints both failed when the print speed dropped to 15mm/s at 0.15mm layer heights, at the boat cabin window area where there are frequent retractions.

After the first failure, I was able to remove the filament with a typical "unload filament" and pull. I followed with a cold pull with some cleaning filament - the result was a pristine and perfectly clean and complete impression of the hotend (including nozzle opening).

The second failure was worse, and I was unable to separate the PLA from my PTFE tube (I'm replacing it tonight).

I had made no changes to the printer and had printed four different beautiful benchies in various other PLAs (including three benchies with the Prusa Silver PLA that shipped with my printer, AmazonBasics Premium, Matterhackers Build series, etc) recently. I used the Prusa PLA profile for the prior prints, and the Prusament PLA profile with these failed prints, but there doesn't seem to be any significant difference between the two profiles. Printer profile was also set to the default.

To me, it seems that Prusament is more susceptible to heat creep through the filament itself than other materials and filaments I have used, and Prusa's Slic3r PE "Prusament PLA" profile (and possibly the default printer profile as well) doesn't take this into account. I would be very concerned with any print at this point with low extrusion rates in Prusament PLA.

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

Today I tried to print a large object with very fine details with Prusament Mystic Brown at 0.1 mm layer hight. The print faild shortly after some small details startet, so even the 0.1 mm Prusament PLA setting isn't safe!

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

I finally a good successful benchy to print at 0.15mm layer heights, using the same gcode that had failed multiple times before. In the time after my failed prints, here's what I've done/changed (in order) to get to this point:

To rebuild the hotend, here's what I did:

The "thermal blanket" is a sandwich (from bottom-to-top) of Kapton (PEI) tape, a layer of woven fiberglass, and a layer of regular aluminum foil. The "thermal blanket" is a bit undersized relative to the top surface of the heater block. Sticky side of tape is attached to the fiber glass, aluminum foil is taped around the perimeter leaving as much of the shiny side of the aluminum foil exposed (shiny aluminum has low emissivity). I used a regular hole punch to cut the hole for the heatbreak, and installed with the non-adhesive kapton tape gently (not tight) against the heater block, and the exposed aluminum foil side facing the heatsink. A small amount of kapton was used to tape the blanket in place, but only enough to hold it (not a full wrap or anything like that).

The "thermal blanket" and the silicone sock I think have really reduced heat transfer to the top half of the heatbreak and lower surfaces of the heatsink. That was the intent at least. So far, it seems to have worked, and I'm not suffering heat creep with Prusament at this time.

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

This implies that heat-creep is the main factor in this problem?

If so, why does heat-creep lead to a clog? And why is prusament with particles more affected than other PLAs? I don't think the thermal conductivity is that much higher.

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

This implies that heat-creep is the main factor in this problem?

If so, why does heat-creep lead to a clog? And why is prusament with particles more affected than other PLAs? I don't think the thermal conductivity is that much higher.

I don't believe heat creep leads to a clogged nozzle, it allows the filament to swell in the PTFE liner and become jammed. The extruder then can't move the filament as its an interference fit within the PTFE liner. Prusament does seem to flow differently to standard Prusa PLA so there may be some change to the thermal conductivity.

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

heat creep... allows the filament to swell in the PTFE liner and become jammed

This is correct, though I'd clarify that for my jams, the swelling was always immediately above the heat break, just below the PTFE tube. As the warm filament is pushed downward, it moves and creeps at a much higher rate - consider a ball or cylinder of silly putty: when you push down on the ball on a flat surface or between your hands, it's vertical length is reduced (it is compressed) while the diameter increases as the compressed material expands in the other directions.

My nozzles were never clogged - in fact, when I removed the jammed filament and compared to a perfect cold-pull, it was easy to tell that the jammed filament was simply too wide to fit through the heat break any more (i measured between 1.9mm and 2.1mm with my calipers).

Once the filament was no longer being pushed into the heatbreak, all of the melted filament ended up just draining out via gravity, and the heatbreak and nozzle were nearly empty when I disassembled everything (the 2.1mm blob on the end neither fit into the heatbreak, nor could be pulled through the PTFE tube).

Prusament does seem to flow differently to standard Prusa PLA so there may be some change to the thermal conductivity

I agree with this - I printed a perfectly acceptable benchy with Prusa Silver PLA with the same gcode that failed with prusament. It also may not be thermal conductivity alone, but other additives and formulations of the PLA may slightly change properties like the glass transition point (Tg); a lower Tg PLA would be more susceptible to deformation at the same temperature.

I'd also add that a jam above the PTFE tube would be related to heat probably from the extruder motor, and a jam below the PTFE tube (like mine) would be heat creep through the filament and heatbreak (and radiant heat to the heatsink) from the heater block itself. It's the same physical mechanism, but different root causes.

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

I have exactly the same problem. Prusament Prusa Galaxy Black, ID 18687197. Printing at 0.15 mm layer height will start extruder clicking and serious under-extruding. Now that I discovered this thread, I'll try a couple of test prints with very low temperature settings and higher printing speeds to see if there is any positive effect.

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

Test print running with https://www.thingiverse.com/download:2996134 that I had 100% failure rate around layers 20-25 with the default settings.
Now the print is proceeding at ~ 2.5 centimeters without any underextrusion.
My rationale for this test was that if the heat creep is caused just a small margin of settings difference, then the profile settings in Slic3r might help.
Changes to print settings (0.15mm layer height, 20% infill, 2 perimeters):

Print Settings
-Speed
--Modifiers
---first layer speed: 15 mm/s (not sure if this is overridden by the Min print speed set below)

Filament Settings (Prusament PLA MMU2)
-Filament
--Temperature
---Extruder Other layers: 200 °C
---Bed Other layers: 50 °C
-Cooling
--Cooling thresholds
--- Min print speed: 20 mm/s

Setup: MK2.5S/MMU2/Hardened nozzle

so it looks like lowering the print temperature by a handful of °C might do the trick

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

No die, around 3 cm height the extruder clicking and underextrusion started again. Bummer. Tomorrow I'll still test other layers at 195

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

Chiming in to say that I'm seeing this exact same issue with mystic green. Jams up and clicks around the "window" section of a benchy along with sporadic under extrusion before it actually jams.

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

No die, around 3 cm height the extruder clicking and underextrusion started again. Bummer. Tomorrow I'll still test other layers at 195

195 degrees wasn't enough to melt the PLA properly -> Prusament Galaxy Black is unusable material for detailed printing at least with my setup

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

Have you realized that Prusament PLA settings uses 215 degrees temperature for all layers. I thing 195 degrees is too low for Prusament PLA.
I have printed the Lion model with Prusament PLA Galaxy Black at 0.1 mm layer and several other models with Mystic Green, Galaxy Silver at 0.1 mm, 0.15 mm and 0.2 mm layer height without any failure. All models were sliced with the Slic3r PE 1.41.3 or 1.42 alpha with Prusament PLA filament profile.

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

Have you realized that Prusament PLA settings uses 215 degrees temperature for all layers. I thing 195 degrees is too low for Prusament PLA.
I have printed the Lion model with Prusament PLA Galaxy Black at 0.1 mm layer and several other models with Mystic Green, Galaxy Silver at 0.1 mm, 0.15 mm and 0.2 mm layer height without any failure. All models were sliced with the Slic3r PE 1.41.3 or 1.42 alpha with Prusament PLA filament profile.

Have you read this thread through? There is heat creep reported by several users.

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

Hi everyone, similar issue here.
I tried to print D.Va's pistol with Prusament PLA pearl mouse and when the noozle reached 2 or 3 mm height it got clogged. Tried again and had the same issue at more or less the same height. Changed spool (same filament), same issue. Changed with the grey PLA that came within the printer, using the same .gcode file and everything went fine.
Switched to my MK2.5 and had the same problem with another .gcode. So I wondered "What changes? Why the first mm are ok and then it gets clogged?" Maybe being close to the heatbed keeps the noozle temperature higher and when it moves the temperature drops. So I rised the temp to 220°C but it still got clogged.
I really don't know what to do, despite the size of the print it stops extruding at 2 o 3 mm height.
It happens only with Prusament PLA, with neon green PETG everything was fine.

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

I finally a good successful benchy to print at 0.15mm layer heights, using the same gcode that had failed multiple times before. In the time after my failed prints, here's what I've done/changed (in order) to get to this point:

I found one silicone sock and will try in a day or two how installing it alone impacts printing

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

Hi,
the nozzle in my printing has been never jammed but the jam has been in a tube, where diameter of the filament is growing. This morning I opened extruder and measured jammed filament, diameter was 2 - 2,1 mm. And this was in a top of the tube. (Pressure and heat may do this in a bottom ??)

I believe, that the real reason for this is crystallization of PLA, dosn't matter, which color.

- When the speed is high, there is newer problems.
- When speed is low, (=more heat energy in extruder) problems can exist and if you repeat the print, the problem comes in same place, same height.

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

I finally a good successful benchy to print at 0.15mm layer heights, using the same gcode that had failed multiple times before. In the time after my failed prints, here's what I've done/changed (in order) to get to this point:

To rebuild the hotend, here's what I did:

The "thermal blanket" is a sandwich (from bottom-to-top) of Kapton (PEI) tape, a layer of woven fiberglass, and a layer of regular aluminum foil. The "thermal blanket" is a bit undersized relative to the top surface of the heater block. Sticky side of tape is attached to the fiber glass, aluminum foil is taped around the perimeter leaving as much of the shiny side of the aluminum foil exposed (shiny aluminum has low emissivity). I used a regular hole punch to cut the hole for the heatbreak, and installed with the non-adhesive kapton tape gently (not tight) against the heater block, and the exposed aluminum foil side facing the heatsink. A small amount of kapton was used to tape the blanket in place, but only enough to hold it (not a full wrap or anything like that).

The "thermal blanket" and the silicone sock I think have really reduced heat transfer to the top half of the heatbreak and lower surfaces of the heatsink. That was the intent at least. So far, it seems to have worked, and I'm not suffering heat creep with Prusament at this time.

Sounds interesting. I'l have to review this when I rebuild with the MK3S upgrade.

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

I agree with this - I printed a perfectly acceptable benchy with Prusa Silver PLA with the same gcode that failed with prusament. It also may not be thermal conductivity alone, but other additives and formulations of the PLA may slightly change properties like the glass transition point (Tg); a lower Tg PLA would be more susceptible to deformation at the same temperature.

Prusament pla and prusa pla have different temerature profiles so you shouldn't use the same gcode

Re: Is Prusament Mystic Brown clogging the nozzle at low speeds?

Mystic Brown seems prone to failure at low extruder volume. Either slow speeds or small layer heights. Increasing print temp to 230 has helped in some cases, but not all. Probably an effect of the copper/mica colored grains in it. Any filled material will present print issues.