just got my MMU2 MK3 up and going.
i'm in the process of the first test print using the sheep.
some tips:
the system is very sensitive to how easily the filaments can load and unload any slight obstruction will cause the pulley to strip out the filament(half moon cut).
1) the spool holders that currently come with the MMU will cause nothing but problems. there is WAY too much drag on the system with them.
i highly recommend getting by pmeyer :
https://www.thingiverse.com/thing:3113520
you can either buy some 1" PVC or 3d print the 85mm tubes but the design is superior to the stock MMU spools
you reuse the exact same parts but now the spool load is transfers from the I.D. of the bearing to the O.D of the bearing.
the spools drag is basically removed and it solves one way the pulley can strip the filament out and cause load and unload problems.
2) make sure the filament can enter and exit the extruder body without catching anything.
my next issue was the filament going through the orange PTFE tube into the extruder. the gap between the small white PTFE tube and the filament sensot board would cause the filament to catch just a little entering through the lower hole onto the Pulleys. i took a round Jewelers file with a tapered end removed the top plate and tube and carefully working around the sensor i knocked down some of the ridges on the extruder just enough so a blunt end filamant would not catch on anything entering the pulley. i used straight and curved pieces of filament to test and retest at different angles that it would smoothly guide the filament into the extruder.
you will have to go into service mode and reset the PTFE tube lengths with the new spool rollers and the modifications to the extruder.
once the filament can move for load and unload easy it will be less likely to strip and cause a failure.
take the time to check this movement.
3) space out the spool holders in a half circle don't place the spools side by side behind the machine. space them out angle them slight like a crescent moon
4) use some bearing oil on the pulley body assembly on the finda shafts with bushings just a light amount of oil to free up the assembly.
double check you knife placement here also.
5) during pulley body assembly for the idler body clean out the elongated holes for the springs that tension the pulleys make sure the spring can float and the body doesn't get hung up on the screw threads. you want that assembly to float on those springs easily to avoid too much tension on the pulleys set them by the manual works well just a slightly under the surface of the plastic.
6) drill out the mmu2-s-holder-lever-a with a 2mm drill bit on the spool holders so the filament again moves freely through it.
7) watch your PLA being brittle from improper storage or age. the constant load and unload will snap the filament and lead to more problems. bake the PLA to get the water out or use new spools for the first runs.
i had to upgrade my original MK3 extruder as i had the old version with the vertical fan assembly. if you have to upgrade yours remember there are additional new parts for the Z bearing holders. since i had to take the entire machine apart to replace the Z bearing holders i also took the oppertunity to switch from the Spiral wrap holders to the new Cloth holders. i recommend first getting the new MK3 rebuild working as a normal MK3 before starting the MMU2 update. don't tackle it all at once. verify the new upgrades work first as a single filament printer.
XYZ Calibration will also change quite a bit with the MMU2 attached. after getting the MK3 printer upgrades as a single filament and getting it dialed in i found i had to go back and lower the pinda slighty after installing the MMU and getting it up a running for a XYZ cal. the extra weight on the frame also slightly increased my Skew so be wary of this as well to avoid damaging the Bed on the first start up.
i'm a noob and i'm sure i will have many more issues as i go along. i used the ready made Gcode for my first print.
lots of work to get to this point.
upgrading my spools.
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
first print...nice. you must have been paying attention to forum posts 😀
I have a Prusa,therefore I research.
Re: just got my MMU2 MK3 up and going.
funny enough i didn't read the forums at all. i wanted an unbiased opinion as i built mine up. i came across the spool conversion via different means which was great since i arrived at the same conclusion.
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
Very nice post. I'm using MMU2 for two weeks now and the filament path is root cause #1 for the issues I've seen so far.
The filament holder need to be replaced. They are working only with softer plastics and perfect matching diameter.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: just got my MMU2 MK3 up and going.
i got the lizard out. and decided to go for a real test with a 5 color benchy.
now i was resetting the PTFE lengths on the service menu and i noticed the other filaments that i had setup before 1-3 had those little stringy tails coming off the tips which mess up the FINDA.
now i was using the provided Gcodes for the Sheep and the Lizard but on the benchy i went with the new PLA prusa defaults in the newest sli3cer. so we shall see what happens.
the benchy will take about 11 hours so i'm crossing my fingers as to what will happen. I also loaded a yellow PLA which i read is either really tough or un-usable due to stringing. everything is on hatchbox filament
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
well i have to say that was pretty amazing.
some of my personal observations.
the first layer on all 3 prints seems to be under-extruded. the rest seems ok but i should run a test and stop it to look at the infill.
there is a bit of stringiness. i'm running at the default 205C temp which i found worked nice for hatchbox on my other 3d printers.
i'm thinking increase retraction and lower temp a little?
i'd love feedback for improvements
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
had first real failure on a print. was caused by the yellow filament and a rather large string that got into the FINDA.
one thing that would be better is if the FINDA ball weighed more. if the center of the ball bearing was Tungsten then you could keep the magnetic properties of PINDA detection with a much heavier weight which would be less sensitive to those strings giving false readings to the FINDA. obviously the Strings are not good anyway but maybe it would allow the machine to kind it save itself.
i managed to blow out the FINDA with compressed air as it was really getting full of Strings. so i obviously need to look up Ramming settings or maybe drop the Yellow only temperature from 205 to 200 or 195C.
one thing i'm noticing is the First layer is always under extruded no matter what i try is there a possible bug somewhere in just the first layer. the other layers look ok. i played with the extrusion multipler and the extrusion width but saw no effect. i've lowered Live-Z quite a bit but it just seems to always under extrude on the first layer with MMU
i'm running the first layer at 215 and then 205 for the rest.
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
one thing that would be better is if the FINDA ball weighed more.
A while ago, I printed an amended selector which used a 9.5mm diameter ball (a lot heavier).
Overall, it didn't make any difference, so I have now reverted back to stock.
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: just got my MMU2 MK3 up and going.
was worth a shot.
i guess the best manual solution would be:
filament comes out of the extruder. it retracts a bit, the extruder switches out for a pencil sharper, filament gets sharp end, extruder swaps back in and filament happily ejects into the selector ready for another fresh round of loading.
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
so yellow is as problematic as people had stated. 2 jams so far caused by yellow with default prusa PLA settings.
i'm running a test with some new ram and speed and temp settings to see if the end of the yellow filament looks better or worse.
all the filaments are actually stringing badly however they are not tripping the FINDA ball incorrectly and they seem to load and unload ok. but yellow is exceptionally stringy. so white is ok because maybe the coloring in the PLA holding in spec and dark colors are ok, but yellow can basically knit a sweater from the strings getting in the tubes and selector body.
some practical color printing i made special versions of the suspension arms for the URSA R/C 3d printed truck to mess around and get to understand how to make STLs for multi-color or materials.
a one color next to a 4 color version of the arm
backside
installed on the truck
what i find is the slicer kind of introduces weak points because of the color change, so the entire main support of the arm is in the silver color with colored panels and covers on top to give the effect while keeping a center core of strength.
the black inlay panels on the back and front for example do not go all the way through, there is a silver core separation between the front and back so there is a back side collection of black inserts and a front side collection of inserts on top of the core silver support.
example of a weak point on a test piece caused by the slicer as perimeters obviously can't mix like infill. mechanically i feel you have to take this into consideration on a load bearing part. this part is also showing slight under-extrusion which i'm working on as well.
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
after all the above i pulled my filament to see what the machine is dealing with on average.
comments, everything is on prusa PLA defaults except for yellow
yellow was stringing to the point of making cotton candy so i used some inland PLA settings and dropped the temp down to 200 from 205.
added 4 seconds to ramming and 2 cooling cycles to get this point.
black has the best tip and all the others have a decent amount of light stringing.
i'm going to leave the temps alone and change the settings on the other colors run another multi color item and pull them again and see what changed.
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
yellow was stringing to the point of making cotton candy so i used some inland PLA settings and dropped the temp down to 200 from 205.
added 4 seconds to ramming and 2 cooling cycles to get this point.
I would go even lower with the temp. maybe 195C or even 190C. Such stringy tip I got only with hot filament printing.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: just got my MMU2 MK3 up and going.
problem is the strength of hatchbox PLA goes down quickly under 205C I need stronger parts so i have to keep the temps up.
i had a power failure last night which messed up my testing since the MMU kept reseting for every flicker even on the APC i have(buying a better APC to try out)
but with the quick tests i put out using the INLAND settings what i found was it was getting rid of the small strings but greatly elongating the Tips they started to become 10cm long. the machine was still humming along but this was not a good solution.
i'm going back to basics again and start messing with one setting at a time and see what happens.
i may not find a solution so it is a question mark at the moment.
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
problem is the strength of hatchbox PLA goes down quickly under 205C I need stronger parts so i have to keep the temps up.
True. Maybe go with ABS 😉
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: just got my MMU2 MK3 up and going.
messing around with all the setting really the ramming has the most effect. but i can see i will need to lower the temps from 205 if i want a better profile for the filament. lighter colors appear to need a lower temperature that is under darker colors.
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
after messing around for a few hours i really didn't get anywhere, the inland pla settings were producing the better results obviously not where they are ideal, however the machine is printing ok, so i guess i'll just leave it. the only change that worked was dropping 5C just on the yellow since that filament was causing more problems.
i found i needed to do some more things to the accessories on the MMU2 to get it a little more stable.
1) I taped the Spool holder bases to the table. i had adjusted one spool holder and in doing so the filament shot out of the selector assembly through the PTFE tube and it jammed the selector because the machine was printing at the time.
after that little screw up... i also kind of discovered at that point that the knife design kind of doesn't work in that it should be cutting anything sticking out but the knife is too far away from the filament holes and it just bends it 90 degrees and then it jams across all 5 selector points. Wawa.
2) i printed out a PTFE Tube Separators. i clamped it behind the selector assembly because my center PTFE was kind of twisting and i felt messing things up a little.
current little test piece
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
skipped 2 layers on yellow on the first 2 changes then whatever was catching let the filament go on the 3rd layer and it kept going after that. the layer skips were mechanical the filament tip on the first use caught on something once the filament has been used and rammed the shape on yellow no longer hung up on the jam.
there appears to be a thin wall bug in slic3r 1.41.1 that caused a problem with the bridging fix.
worked fine as a torture test.
typical ringing and Moiré pattern i always got with my MK3 no matter what i did to try and fix it.
the hinges came out fine and it works as a fidget toy
the little red dots is what was suppose to be the bridging support that slic3r bugged out on. this was a 3 color run
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
so far after the first 2 days and making mechanical adjustments at that time, i had one model with 2 layer skips that was my fault. otherwise the last 100 or so hours of printing, almost 2 weeks, have been mostly problem free.
There is now some weirdness with the MMU2 on resetting which i documented here:
https://shop.prusa3d.com/forum/hardware-firmware-and-software-help-f56/mmu2-homing-issue-t26043.html#p117637
i don't know if this issue will continue to get worse with more and more hours on the machine for now it isn't effecting the loading or unloading of filaments but that could change if there is some kind of electrical failure occurring. i think as more and more people get hours on these machines it should be reported as a bug or problem.
I decided to make some mechanical changes to try and see if things will improve on MK3 printing issues.
I've changed from the rubber feet to hard feet:
https://www.thingiverse.com/thing:2805753
changed out the Z mounts from stock to:
https://www.thingiverse.com/thing:2779123
changed the Y motor holder from stock to:
https://www.thingiverse.com/thing:2942590
I've also read the mk3 better printing guide, which recommend some of the changes above.
in reading the guide i have gone back and reduced the tension on the extruder spring tension. lowering the tension to produce less bite into the filament as it goes into the extruder down into the nozzle. the claim is the bites from the pulley are causes some of the moire patterns in prints due to inconsistent nozzle pressure caused by the deformed filament shape.
i have seen some positive changes on some test prints. nothing ground breaking yet.
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
and like a dummy i snapped my X-end motor part.....
gurrrrrr i was attempting to tighten my X belt and snapped the new pieces i just printed 2 weeks ago. 👿
“One does not simply use a picture as signature on Prusa forumsâ€
Re: just got my MMU2 MK3 up and going.
ouch, had mine about a week I am up to 2000 changes no issue 2 times in a row. stock hardware stock software. well not spool holders...
I have a Prusa,therefore I research.