PRUSA edition heat break easily jam/clog with PLA  

RE: PRUSA edition heat break easily jam/clog with PLA

Reduce or disable retraction is an obvious option. 

RE: PRUSA edition heat break easily jam/clog with PLA

i have to say i had the same issue and it was befor i upgraded to the mmu2 aswell my fix was just replace it with e3ds one occasionally i would swap them out just to test if my theory is correct both with mmu2 and without and within 3 hours of printing with the pruse heatbreak installed it jams when i pull/cut out the filament its a 2mm thick 5 mm long thread in both the mmu2 and stock mk3s and just for kicks i installed it in a different direct drive printer i own and yes same again it blocks i initially put it down to me building the extruder wrong ive had friends check it out and some have complained of the same issue with thier printers and in scotland their are not that many prusa owners so so my 3 friends that all live locally and have complained about the same issue seems like its hardly a coincidence 

RE: PRUSA edition heat break easily jam/clog with PLA

I increased my temperature from 210°C to 220°C and reduced retraction distance from 0.8mm to 0.4mm and was able to complete a troublesome print.

My biggest question at this point is -- why aren't more people complaining about this? If the heat break is indeed defective for PLA, the most commonly used filament, wouldn't this affect nearly every user?

RE: PRUSA edition heat break easily jam/clog with PLA

Posted by: sinoth

[...] My printer is in my garage which hits ambient of 35-40°C. This likely exacerbates the issue :/

This is likely the root cause, or at least a major contributor, to your problem. The E3D V6 hotend used on the Mk3 is rated to operate in ambient temps of up to 40C. At that temp, the heatsink and cooling fan can't provide enough cooling and the cool part of the hotend can warm up to temps high enough to soften some PLA filaments.

The first thing I'd try is improving cooling or at least airflow to the extruder assembly. Last year during the peak summer months, many people reported a simple fan blowing and moving air helped.

Alternately, take this as a good opportunity to master PETG or other filaments that soften at higher temps!

RE: PRUSA edition heat break easily jam/clog with PLA

Posted by: sinoth

My biggest question at this point is -- why aren't more people complaining about this? If the heat break is indeed defective for PLA, the most commonly used filament, wouldn't this affect nearly every user?

It's not broken, it's just a little piece which contributes toward jam/clog. You need to meet certain criteria to make it jam. Like put it in box (increase the ambient temperature), print slow (low volumetric speed), have many retractions ... Some filaments are tend to jam easier than others. 

I had jams already on MK2/MK2.5/MK3/MK3s with all the different extruder head variations and with PLA/HTPLA/PETG/ABS/FLEX. This is part of 3D printing. Many people just learn to handle this issue by understanding why it's happening. There are also lucky people which are printing just generic "big" stuff/low resolution with default settings without a box and regular 20C ambient temperature and just don't have those kind of issue very often. 

As an example: My wife printed some figures last weekend and it was pretty hot in the room. She also used our "silent" settings. MK3s jammed. I told her to use default settings and reduce the room temperature. Same model, same printer printed without any issues the second time.

RE: PRUSA edition heat break easily jam/clog with PLA

RE: PRUSA edition heat break easily jam/clog with PLA

Just to be sure, this is the heartbreak I should be ordering?

https://e3d-online.com/v6-titanium-heat-break-1-75mm

I have the same issue with printing PLA: underextrusion and/or clogs. Never had this problem with printing NGEN Filament for example. See my other post as well: https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-hardware-firmware-and-software-help/prusa-mk3-is-clicking-and-then-under-extruding/paged/2/

Best regards,

Jan

RE: PRUSA edition heat break easily jam/clog with PLA

You may not need the expensive Titanium heatbreak.

Here is the standard stainless steel version:

https://e3d-online.com/v6-heat-break

E3D claim better performance with their Titanium heatbreak, but from what I have read on the forum, it does not seem entirely too certain, that this claim is true.

The heatbreak delivered by prusa is stainless steel.

RE: PRUSA edition heat break easily jam/clog with PLA

I have experienced this issue, but only with Colorfabb PA-CF low warp. I've since switched to Nozzle X and e3d copper heat block - no difference there.

It just clogs about 10-15 minutes into any print - tried all kinds of slicer settings but none of them made a difference. My filament ends looked exactly the same as yourself. However don't have this problem with normal PLA - only with "filled" PLA like PA-CF. Was thinking it was the distinctive heatbreak so interested to hear in what others experienced.

RE: PRUSA edition heat break easily jam/clog with PLA

Posted by: sinoth

I increased my temperature from 210°C to 220°C and reduced retraction distance from 0.8mm to 0.4mm and was able to complete a troublesome print.

My biggest question at this point is -- why aren't more people complaining about this? If the heat break is indeed defective for PLA, the most commonly used filament, wouldn't this affect nearly every user?

they are one of the tell tail signs is the extruder clicking now google prusa i3 mk3 extrudor clicking yep they are all suffering from the same but alot of people dont experience this because there are other factors added to the heat break that force a block as alreaady stated by a number of other posters

RE: PRUSA edition heat break easily jam/clog with PLA

Posted by: Tim

[...] And you can see the pumping effect in the filament stub.  Where 1.75mm filament pumps down into the melt pool and squishes out filament around the cold new filament, building the stub up in the 2.2 mm zone. After enough of these pumps, the stub is now long enough it is completely outside the melt zone, and too large to fit down the 2.0 mm neck. 

Tim, this and your previous comment about pistoning of the filament up and down in the heatbreak during retraction are key points, and explain why the 1st layer or simple prints (with fewer retractions) will succeed while larger won't. The build-up of heat also explains why PLA with relatively low melt temps will fail on a printer that can work with PETG all day without issue. This is a culmination of many factors.

Michael Hackney (well known KISSlicer advocate) has a very good article on retraction. He noted many of these same issues back in 2016, but also noted that molten filament will act as a non-Newtonian fluid when compacted (i.e. during de-retract moves) which is sounds like a contributing factor to exactly what you've described. Filament comes out easily but doesn't compress back the same way, eventually building up. At the time of his writing, only KISSlicer supported a separate de-retraction speed, but current PrusaSlicer (and presumably others by now) does support Printer Settings->Extruder 1->Retraction->Deretraction Speed. I've set mine separately from retraction speed (which is better higher), using 50mm/s for retraction and 25mm/s for detraction moves. While I've never suffered from the "step-child" effect, this has let me go with faster retracts without encountering extruder clicking.

I'm sure this is yet-another "not a silver bullet" tweak that may incrementally help with this problem.

RE: PRUSA edition heat break easily jam/clog with PLA

protopasta recommend increasing the temp when using thier filament upto 240 ...  i found this video a few hours ago ... and after testing with generic pla i can confirm printing the generic pla at 240 on a print with lots of retractions as eased the problem previously when i tried printing i would get the clicking extruder within 30 mins of the print and then completely blocked/ ground up filament after an hour this time around with the increased temp i didnt experience any issues

RE: PRUSA edition heat break easily jam/clog with PLA

Very useful video.  As someone with no plans to go MMU, looks like I might order a straight through heatbreak.  I've got a bunch of other stuff that I've been waiting to do on my printer and this seems like a good thing to add.  Thanks for posting.

RE: PRUSA edition heat break easily jam/clog with PLA

the stock e3d heatbreak works fine with mmu2 once you sort out its pull settings and script a temp change befor you remove filament

RE: PRUSA edition heat break easily jam/clog with PLA

Posted by: karldavy149

the stock e3d heatbreak works fine with mmu2 once you sort out its pull settings and script a temp change befor you remove filament

Sounds like replacing one hack with another one 😀 

RE: PRUSA edition heat break easily jam/clog with PLA

yeah but replacing numbers in a program is not so much a hack its settings that any real mmu2 user will be making anyway u just have to slightly adjust for the stock heatbreak

RE: PRUSA edition heat break easily jam/clog with PLA

Actually current default MMU2 values are working pretty good. Do you mind post the new values which are working for you with the e3d heatbreak?

RE: PRUSA edition heat break easily jam/clog with PLA

So earlier this week I ordered a stock E3D heatbreak and yesterday in one go I replaced the Prusa heatbreak, put in a new E3D brass 0,4mm nozzle, and replaced the pfte tube.

First two prints went great, during the third print however I heard the dreaded 'clicking extruder' again. So underextrusion as a result. This is getting frustrating, I really need to babysit my printer all the time.

I'm using Prusa PLA, 0.2mm quality MK3 settings, 230°C temperature, 21°C ambient temperature. 

RE: PRUSA edition heat break easily jam/clog with PLA

Posted by: jan.v37

So earlier this week I ordered a stock E3D heatbreak and yesterday in one go I replaced the Prusa heatbreak, put in a new E3D brass 0,4mm nozzle, and replaced the pfte tube.

First two prints went great, during the third print however I heard the dreaded 'clicking extruder' again. So underextrusion as a result.

Does the clicking stop if you dial speeds back to 50% using the front knob? If yes, then adjust your settings in your slicer accordingly. If it's happening when you hit infill parts of the print, set infill speeds way back. The Prusa default of 200mm/s is very aggressive. Also be aware of temperatures. The E3D V6 is rated to operate up to 40C ambient temps. If you are printing in a warm room or enclosure, PLA filament can soften prematurely in the extruder and cause a variety of problems.

RE: PRUSA edition heat break easily jam/clog with PLA

I will try that with my next print, never dialed it back.

Example of what I mean: