Filament Tip Tuning prior to MMU Install
I have an MMU2S on order, but while I wait I'd like to see if I can use any of the time to try to find filament profile settings that should work ok for filament tip shape that can ultimately be applied later...when my MMU arrives and can be installed. I thought maybe I could experiment with my stock MK3S using ColorPrint manual filament changes to eject the filament using all the PrusaSlicer "Toolchange parameters" to simulate what would normally apply to an automatic MMU2S eject. I ran some quick tests today and I'm now thinking this method won't work. In my brief experience I saw tip variation maybe just from how long it took me to confirm and press the selector when the printer asked for filament change. Or maybe the variation is from my manual pull speed or timing. In any case, several of the filament tips had extremely long (up to 40 mm) strings that I've never seen before with normal printer filament changes. I don't know if I should conclude that these tips are an artifact of my test method (being flawed??) or the long strings are really what I'd see with an MMU given my input parameters.
1) Does anyone know if (or believe) my test method of trying to use a manual colorprint filament change is fatally different than an MMU2S auto filament change. Clearly, I can't replicate filament pull speed or even exact timing of the pull.
2) Has anyone tried filament tip optimization (without MMU that would apply to MMU) using another method?
3) Also, while I'm asking...has anyone heard from @Antimix recently? I noticed he hasn't posted anything on the forum in the past 2 months and given his Dribbling slicer I thought that was unusual. I hope he's doing ok and wasn't affected by COVID or otherwise.
Thanks.
RE: Filament Tip Tuning prior to MMU Install
i don't think testing it manually is going to be representative of what the mmu will do.
the reason is that when you do a filament change via the mmu a number of cooling moves will be done to try to shape the tip a bit better.
personally i haven't spent too much time worrying about the tip shape, my problems with the mmu (and there have been many) was in other places.
like getting both the sensor in mmu and the sensor tower on the extruder to dialed in just right and also doing A LOT of troubleshooting that eventually turned out to be a bad power and signal cable between mmu and printer control box.
my filament tips isn't that great, especially with petg but most of the time it works pretty well anyway.
RE: Filament Tip Tuning prior to MMU Install
@torbjorn-j3
Thanks for the reply!
I've since received and installed my MMU and strangely I didn't need to tune my settings to get good tips. Default Prusa profile settings have worked well for me. Most tips look ideal, but every once in a while I'll see a stringer...which fortunately hasn't caused me any issues. I've only used Prusament PLA & PETG and Hatchbox PLA so far, but have tested 16 different rolls with consistent results.
Related to filament tips, I did replace the hotend PTFE tube with a new stock spare replacement while upgrading my MK3S even though the tube was already suppose to be a 1.85 mm ID tube as configured. I had noticed during disassembly that the installed PTFE looked larger than my spare. Comments made by others in Prusa's online MMU2s install guide said to be sure to replace it, so I did. I'm sure this had a positive effect on my tips since they are definitely smaller than they were prior to my MMU2S upgrade.
I don't know if I've gotten lucky or what with my MMU2S install, but it's turned out better than I thought. Surprisingly much better. I did read a lot prior to ordering and followed many standard forum suggestions on replacing MMU2S PTFE tubing with larger diameter tubes, stock selector, rear PTFE holder, adding an LED to Extruder IR sensor, and using rewind spook holders, but regardless it still seemed to go smoother than I expected given that it worked from first print. I love the additional capabilities that the MMU has provided.
Now if there wasn't so much filament waste I'd be printing with it all the time.
RE: Filament Tip Tuning prior to MMU Install
the led mod can be very helpful, there is also a modification that makes it easier to adjust the sensor tower by using a screw on the side.
takes away the guessing and randomness when you have to adjust it.
led mod + that adjustment screw helped me a lot to get flexible filament working, i know it is not officially supported to use flexibles with mmu for obvious reasons but if you dial it in just right it can work.
also getting short ptfe tube in extruder up against heatbreak with no gap is important plus i also had a build up of plastic in heatbreak and didn't realize it at first causing very strange strange tips (jam at unload due to too large tip, had to pull it out by force) and behaved as if i had too low temp, replacing heatbreak with non prusa specific and titanium worked.
RE: Filament Tip Tuning prior to MMU Install
there is also a modification that makes it easier to adjust the sensor tower by using a screw on the side.
takes away the guessing and randomness when you have to adjust it.
I had run into that sensor tower mod at one point, but never printed it out. I'm not sure where I had seen it, so I'd appreciate it if you can post the link. I'd like to have the reference if I need it in the future. Thank you!
I should have said "hats off" to the community that has learned and worked, and published their efforts to optimize the MMU2S. I'm sure there are many I owe thanks to for my relatively easy install. Hats off to Prusa too for creating it. Given my experience it seems that Prusa might be getting too many complaints and not enough praise for what they accomplished with the MMU2S. It's not foolproof, but certainly can work.
I never did end up using Antimix's dribbling version of Prusa Slicer. I didn't want to resort to using an unofficial build, especially since @Antimix hasn't been heard from in a while....at least here.
RE: Filament Tip Tuning prior to MMU Install
@corfam
I would wait until you have your MMU and see how it performs. I added the MMU to my mk3s with no mods at all and its performing perfectly. I am using Prusament PLA and PETG, as well as Hatchbox. Another thing is make sure your printer is performing well before the upgrade. I tweak my extruder multiplier for each filament I run (using thin wall calibration cube) and figure out what temps work best (Prusament seems to like the low end to middle of Prusa recommended temps). I chose not to add any mods or steps until I ran it and it turned out fine.