Severe underextrusion and clicking on 2 (!) different PRUSA Mini
Hello, I am having problems with my PRUSA MINI after 6 months of usage. I am experienced and have several Prusa printers. While trying to resolve the issue, my 2nd Prusa MINI which is only two weeks old, is having the same exact issue.
1st printer:
It started underextrusion and clicking without an obvious reason
- I changed the PTFE tube
- then the nozzle to an original replacement par
- then I disassembled the extruder gear and cleaned everything up
It hasn't helped. The first layer is perfect but then when it gets to normal speed upon the second layer it starts clicking and grinding. I tried black, white and red PLA. All of them worked fine before.
I played with the gear tension. I unscrewed it and live adjusted it when there was clicking, but I can go from completely loose (underextrusion) to extremely tight, but only the sound changes.
The only thing which has helped is reducing the (standard 0.15 setting) speed to 50% which is not a solution obviously.
2nd printer:
Underextrusion starting after 2 weeks of normal use.
- Tried different filaments
- Did several cold pulls
- Disassembled and cleaned the extruder gear several times.
Both printers got the same exact problem: Perfect first layer then clicking/grinding on the second layer. Sometimes it the clicking disappears during a layer and then reappears at the infill of the next layer.
Both printers do better when decreasing the printing speed.
The only thing which could indicate what the issue is about is the fact that at the beginning of the layer, there is less filament extruded and more clicking then in the second half of the layer. It disappears each time so to speak.
The PRUSA support could not quite help me. They told me to increase space under the nozzle by decreasing the Z-adjustment, but it didn’t change anything.
The second thing is increasing print temp which helped a bit (220°C for PLA)
Now at least when I print with the second printer, the clicking disappears after the second layer.
I am pretty desperate now, because I am losing more and more printers.
If such a problem is appearing shortly after purchase, then I am not very confident to buy more of them.
Thank you in advance!
Print example 1st printer:
hard to see, but there are gaps between the lines.
Print example 2nd printer:
RE: Severe underextrusion and clicking on 2 (!) different PRUSA Mini
a couple of things...
Does the same thing happen if you swapped out the filament? or did you check to make sure the filament is in spec? You would need a caliper, get the diameter of the filament and write it down. Pull a meter of filament from the spool, check the diameter and write it down. Do this till you get 8 readings, then add them up and divide by 8 to get the average. The tolerance for variations of the filament size is + / - 0.05, so between 1.7 and 1.8. If at any time the readings are out of that range, then the filament will give you problems.
You mentioned on the first printer that you removed the nozzle. On both printers, did you check to make sure there is a small gap (between say 0.5 and 0.25mm) between the nozzle and the heat block? If the nozzle is flush you can get heat creep where the heat travels up in the hotend and softens the filament and can cause a clog.
Did you already check both of these?
Shane (AKA FromPrusa)
RE: Severe underextrusion and clicking on 2 (!) different PRUSA Mini
@fromprusa
thanks for your quick reply. I tried 3 different high quality filaments and now I checked the diametre which is exactly 1,75 mm.
There is also the above mentioned gap.
I pulled out the extruder motor and checked if it has enough force, I also pushed the filament manually through the ptfe pipe too see if there is any resistance.
It can only be a heat problem I guess. The filament is loaded very well and the first layer is perfect. When it comes to normal speed, it starts clogging. As it disappears after some seconds during a layer it is a kind of temperature equilibrium settling or whatever..
RE: Severe underextrusion and clicking on 2 (!) different PRUSA Mini
Ok, I found the solution. It is the heat break PTFE tube, which is too short or whatever. If you do the official PTFE tube replacement manual, it is not working. You need to push the heater up, then fasten the three small screws on the side and only then fasten the ptfe fitting on the top. Printer number 2 is working properly now. When I tried to unscrew the micro screws on the side, one went round and it never came of. I tried to drill it out, but it didn't work. I think because the screw is harder than the casing. You can hardly access with a drill bit. Now I totally broke one of my MINIs. Need to purchase another extruder unit now.
RE: Severe underextrusion and clicking on 2 (!) different PRUSA Mini
@maximilian-loeber
tiny dab of superglue on the end of the grubscrew and glue a longer screw too it so you can grip an dpull while unscrewing?
RE: Severe underextrusion and clicking on 2 (!) different PRUSA Mini
i had similar under extrusion and uneven printing across large flat surface areas, increasing the temp to 225 and the bed to 65, plus slowing the printers infill speeds to the same as normal perimeter speeds (40mm/s) solved this for me. (amazon filament, and sunlu grey), i also messed about with flow rate, upping it to 100 for some prints
I swapped to a different filament (and used some nozzle cleaning filament) and it worked fine at 215 and 65 bed, so i do think the filament makes a huge difference to how it handles it. (silk warhorse copper)
i'm now printing on stock temps with petg and its coming out perfectly, way way better than the pla was being handled
RE: Severe underextrusion and clicking on 2 (!) different PRUSA Mini
I am having the same issue with my Mini. I bought a Bondtech dual gear extruder, bought new OEM replacement nozzles, changed out the PTFE tube in the heat break, no luck. I guess I will try to cut my own tube and see what happens. This is getting crazy.
RE: Severe underextrusion and clicking on 2 (!) different PRUSA Mini
I had the same issue after 2 days. started clicking and under extruding. I followed the Prusa guide and ended up changing the ptfe and now back to normal. I have ordered 2 meters of PTFE and have printed a jig to aide the cutting.
One weird thing was I did I few cold pulls but didn't get anything out and then did a final one and a big slug of plastic came out. The thing I learnt was unless you can see the brass of the nozzle when the fitting and PTFE is removed then you probably still have a slug of plastic stuck. Now I know think I could do the job in 10 minutes pretty easy.
RE: Severe underextrusion and clicking on 2 (!) different PRUSA Mini
I ended up replacing the extruder with a Bondtech.
However you need to tear down and completely clean the stock extruder since it is extremely sensitive to ground up bits of filament. Yes, the PTFE and heated block positioning started the issue and now the extruder is paying the consequences of that problem, unfortunately.
RE: Severe underextrusion and clicking on 2 (!) different PRUSA Mini
Interesting contribution to this topic:
Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen.