RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
Ok, I did three runs with the Bondtech heat-break:
Prusament PLA, default PrusaSlicer profile, 215C/60C, 0.15mm layer height
1. - Bondtech stock PID values, three individual prints one-by-one
2. - Autotune with 5 runs, three individual prints one-by-one
3. - Autotune with 10 runs, three individual prints one-by-one
Disassembled the hot-end: unloaded the filament, warmed it up to above 260, did a cold pull, warmed it up again, loosened the nozzle, cooled it down, disassembled the heater, thermistor, nozzle, heat-break, head.
Assembled with the old, original heatbreak, redone the paste, warmed it up, fastened the nozzle, instantly made a cold pull, recalibrated the SPINDA probe. Restarted the printer to eliminate the previous PID values.
4. - Prusa stockPID values, three individual prints one-by-one
To summarize, I have to say, that there is definitely something wrong with the Bondtech part... I already sent a message to the customer service, will see if they respond.
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
If needed let them know that I had the same issue (and still have) and that it was reported on 9 September 2020 with subject "Could not print flawlessly a simple 4x4x36 mm cylinder using Bondtech Dual Drive Extrusion Upgrade Kit for Prusa Mini" and that also at least one other person from the forum had same/similar issue ( https://forum.prusa3d.com/forum/user-mods-octoprint-enclosures-nozzles/bondtech-heatbreak-any-good/#post-260023 ).
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
Yeah, sure, I will. Fortunately, for me, the original heatbrake works well for PLA what I'm printing most of the time, only felt issue with longer and higher 225+C prints... Would be awesome to figure this out to have that option though 🙁
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
I still wonder if all these issues are not connected to the extruder motor that could not deal with the additional pressure that Bondtech heat break potentially requires because of the shorter heating zone. Also I think that the Bondtech dual-drive extruder itself has higher movement transfer rate which should mean more stress on the motor for same movement. Also it has more gears => more friction.
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
Well, it's a possibility, but in that case, it would be still a design flaw at the heatbrake, as the target "audience" is the Prusa Mini users, with the given motor. If I would have more patience, I would replace the extruder also now and make all these prints again, but kind of tired of this now 🙂
My tip is, that the PID values should be refined, giving it more "thermal puffer" or something similar. It's clear that the autotune settings were not improving, but made things worse, so the PID has an actual effect on this behavior. I hope the temperature management is the key to this and Bondtech would figure it out.
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
About the PID settings - if you after step 3 have done step 4 and have repeated the test with the Bondtech PID settings and have received the same results as step 1 I would believed it. But my experience with 0.10mm prints tells me that the things worsen after each next print until a filament change is done so may be the PID value does not count at all. What I found is that rising the temperature/flow fixes the issue for some time but later things go wrong again and not easily fixable on the fly. May be the distance between the extruder and the heat break is significant factor that needs some "buffer" and that's the reason why PRUSA is still using the same heat break design with a longer high temperature zone even with the Prusa Mini+ in order to have consistent prints.
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
@nis
Because the extruder started clicking and then you fixed the PTFE tube wasn't it possible that the extruder was clogged and the reason for the later ruined layers were not in the heat break?
What is the final result when printing in spiral vase mode with the Bondtech heat break?
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
@prusatester2020
I unloaded the filament to fix the PTFE tube.
I also unloaded the filament to install the bondtech heatbreak. No clicking with the bondtech heatbreak.
The results are the same as before: inconsistent extrusion.
I've written a message to Bondtech about this and send them the links to the posts here.
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
May be you needed a cold pull using nylon until you clean the Prusa heat break ...
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
@prusatester2020
Maybe. It has only printed pla, and I have no nylon.
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
The cold pull should also be possible with PLA/ABS/... may be not so effective but better then nothing.
b.t.w my Bondtech dual extruder gears look a little worn/"rusted" - are yours also have the same look? And could the missing particles clog the nozzle?
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
@prusatester2020
Oh, I have done many cold pulls with PLA. On both heatbreaks.
I bought my bondtech stuff start November, so it's pretty new. I'll take a picture later today.
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
Here is some additional info concerning the problem:
- I took a video of the 3D printing process which shows the extruder movement on the left part of the screen using an indicator: https://www.udoma.org/tmp/PrusaMini/VaseModelExtruderSteping.mp4 . I could not see any inconsistencies in extruder motor movement which means that it is not involved into the problem reproduction. Here is the final 3D print:
. - I just noticed that the Original Prusa Mini heat break was NOT made of stainless steel while the Bondtech one IS. It looks to me that the Prusa is made of brass of some other alloy that possibly has better thermal conductivity. Could this explain the issue !?! Also the Prusa heat break threaded end which is attached to the nozzle has a external cone form which should be designed for a reason.
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
@prusatester2020
I think you're right about this, and I also think that there is a thermal property difference and issue comparing the two parts. For example if I used stainless nozzle with the Bondtech heat-brake, I really struggled to have a decent print, it somehow emphasized all the faults we're experiencing. I felt it lacked the "thermal mass and stability" of the extraction... With the steel nozzle, I ended up printing PLA like 227C and felt like when it is 210.... With temperatures of 215, the PLA came out matte, rigid, under extracted, which is likely around 190-195 in normal circumstances. You felt the same that with the bondtech heat-brake, you needed a bit more temperature to have the decent flow.
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
Hey
That's my issue, my conclusion was that there is some buffer zone in heatbreak - it has to do with prusa profiles I think.
Why? Because after being infuriated with both hotends I bought a v6 with titanium heatbreak winch had same "over and under" extrusion problems.
Bondtech heatbreak on my printer, bought it like a week after release: had sporadic jams but more visible were those thick lines after retractions.
Thinking about profiles...it may be the retraction but there is ONE more thing you and me didn't think of...Linear Advance..winch is responsible for fluent extrusion...
could you try setting it up anew and checking the results? It may be the solution.
About stock hotend and PTFE - the prusa heatbreak solved all my issues but its not "permanent" , the PTFE inside uses up with time and shrinks, the PTFE should be 43.2mm long but after time , due to heat and compression - it shrinks over 2mm wnich causes the jamming.
Solution is simple - replacing it altogether , I ordered a few units from prusa and replace them each month or two, addtionaly right now im testing home-made ones with 120* chamfer.
When package arrives ill be also testing the pneumatic connectors winch will bypass those ptfe tubes, no more brass threads , just simple bowden connectors like in other printers where PTFE comes directly to the hotend, in case of shrinkage Ill just push it more..
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
Sorry @pinkie-pie but I could not wait anymore and just finished replacing the Bondtech (on the right) with the Original Prusa (on the left) and here is the result:
As it is clearly seen using Bondtech heatbreak the 3D print starts OK until 20-30% and then the under/over extrusion follows.
About the "Linear Advance" - where is this parameter? Inside Mini? Hopefully someone else which still uses Bondtech will test it and share the results.
About Bondtech - they are now investigating the issue and I hope that they are also monitoring this thread. If I were you and did not reported the issue to them yet I would do it.
I also ordered additional PTFE tubes in case I need them. After they shrink if you lift up the heatbreak and use the same PTFE tube does this solves the issue or at least extend the time until next PTFE changes? Will Capricorn PTFE be better/permanent solution?
I also would prefer that the Bondtech solution is working so after I cleaned their heatbreak I saved it for later use. I also hope that the solution you are trying to achieve will be successful - please let us know how it is going.
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
I tried calibrating my printer using Teaching Techs calibration guide. It includes linear advance.
It didn't help.
I have tried upping the temperature to 225C. It helps but introduces other artifacts in benchies that I can't get rid of.
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
The ptfe could be lifted a few times but with time it shrinks so much that you can't lift it much higher.
No, I didn't report the issue to bondtech - only talked with the creator (Oloof) but we couldn't solve the issue too.
If you can - try mailing them, It may be that linear advance - it is set in the gcode for filament as:
M900 K{if printer_notes=~/.*PRINTER_MODEL_MINI.*/ and nozzle_diameter[0]==0.6}0.12{elsif printer_notes=~/.*PRINTER_MODEL_MINI.*/}0.2{elsif nozzle_diameter[0]==0.6}0.04{else}0.05{endif} ; Filament gcode LA 1.5
{if printer_notes=~/.*PRINTER_MODEL_MINI.*/};{elsif printer_notes=~/.*PRINTER_HAS_BOWDEN.*/}M900 K200{elsif nozzle_diameter[0]==0.6}M900 K18{else}M900 K30{endif} ; Filament gcode LA 1.0
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
@nis
It sure looks like some kind of pressure build-up to me.. just I dont know why and how.
When I tried V6 with all metal hotend, I had very similar issue with thicker lines every few layers.
RE: Strange extrusion problem using Bondtech extruder and heat break on Prusa Mini
Perhaps a heat oscillation that builds up over time. Which would explain why the start of the cubes usually looks good.
I'm not sure, but I don't recall seeing it in the graphs in octoprint.