Filament feed problems printing 2 colour sheep on new install
1st attempt. Failed when a tiny bit of material got left behind while swapping materials. Almost didn't see it. Could feed material in manually just fine, eventually noticed a little bit of white on the blue material I was pushing through. Fixed problem. After that, MMU could not feed filament through and kept failing. I suspect it wasn't aligning the bearings correctly with the gear.. I kept trying to feed through manually, and eventually gave up when it started printing without any filament. I have no idea why it didn't detect this problem (yes, I did check the IR sensor was working). Possibly the filament had somehow jammed after passing through the IR sensor (but if so, I had no problems removing it).
2nd attempt worked perfectly, started printing 50% of the head of the sheep. Then the print dislodged from the board. Arrggh! 😉
3rd print, with rim to try and keep it adhering to board. Repeated MMU failures. Most of the time while unloading. Generally when I tried fixing it manually I could not see any problems. Once the filament was deformed near the MMU while it still extended almost all the way through to the extruder. I have no idea how this happened. I had to remove the hose and push it through in the other direction.
Sometimes failures don't occur as described. The extruder returns to the home position, the green light comes on the MMU, pushing the control wheel on the Prusa seems to resume in these cases (after fixing the problem). Particularly loading problems. Also noted that Prusa says to push control wheel to return temperature back to normal print temperature, on one occasion I tried this and it ignored me every time.
Is it normal for prints to require so much manual attention?
I notice that the filament often has a tail after such problems, which I cut off. Wonder if this could be a problem, at least for unloading.
Also I suspect the blade is not cutting the filament when I tried to manually test this. Not convinced this is the cause of my problems however...
RE: Filament feed problems printing 2 colour sheep on new install
G'day,
the orange tube between MMU and Hotend delivered by PRUSA is very tight. They tried to make it perfect and delivered a very precise tube for this.
Take it out and store it somewhere and replace it by a cheap chinese version which has an inner diameter of 2mm. The tube needs to be 360 mm long and you should create a camfer on both ends by using a 4mm drill and slowly create the camfer.
Also make sure, that the IR Sensor is pushed as much to the right side on the Extruder as possible, in that way that you can still use the screw holes.
In addition I printed my self these automatic self rewinding spool holders, as the filament buffer creates too much resistant in the whole system.
I use this and don't have any loading / unloading problems since that time.
The cutter on the MMU is, I would name it, useless. It doesn't really cut at all and after a while it even flips out of its holder.
RE: Filament feed problems printing 2 colour sheep on new install
Personally, I would use 2.5mm ID tubing and only chamfer the top end. I have also drilled out the lower Festo to 3mm.
The cutter is not currently used and can be left out.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
RE: Filament feed problems printing 2 colour sheep on new install
Also make sure, that the IR Sensor is pushed as much to the right side on the Extruder as possible, in that way that you can still use the screw holes.
In addition I printed my self these automatic self rewinding spool holders, as the filament buffer creates too much resistant in the whole system.
The instructions say "Move the chimney as far left as possible (red arrow) and make sure, that the IRvalue is “0”."
I am confused, do I want this is far as possible left or as far as possible right?
https://prusa3d.com/downloads/manual/prusa3d_manual_mmu2s_eng_1_00.pdf - section 7.1 step 5.
What self rewinding spool holders did you use? I think I saw a model somewhere just making sure I got the same ones.
Today I noticed that the filament buffer results in the filament being pushed into a right angle at the inlet of the tube to the printer, when the filament has been retracted out of the nozzle. One filament is currently broken, the other looks like it will need to be cut at the right angle. So maybe not the best solution.
RE: Filament feed problems printing 2 colour sheep on new install
Currently trying https://www.thingiverse.com/thing:3338467 - only have one printed however, so can't really check if it is going to help just yet.
RE: Filament feed problems printing 2 colour sheep on new install
Currently trying https://www.thingiverse.com/thing:3338467 - only have one printed however, so can't really check if it is going to help just yet.
I have 5 and they are what I recommend so far, but I'm not entirely happy with them. The main issue is just getting the tension correct. Too much and it adds drag and you get tool change failures. Too little and you get filament everywhere.
RE: Filament feed problems printing 2 colour sheep on new install
I have 5 and they are what I recommend so far, but I'm not entirely happy with them. The main issue is just getting the tension correct. Too much and it adds drag and you get tool change failures. Too little and you get filament everywhere.
Guess I will try the auto-rewind spools since they are recommended but I love how even you say these are difficult to dial in as well. Granted I'm new to prusa machines but with mmu2s, I feel like I'm "fiddling" with the machine as much as I used to have to "fiddle" with my AnetA8. Guess I got spoiled with just the basic MK3S because it required no adjusting after the initial setup/fine tuning phase.