Overhead filament feed
I've moved my MMU to my workshop where I have filament spools hanging overhead. It works perfectly.
Also...that blue that's printing is a transparent ABS filament that's years old and very brittle. There's no way I could get that stuff to work in the Palette, but the Prusa MMU is handling it just fine (knock on wood).
Re: Overhead filament feed
Nice work.
What are the connectors between PTFE feed tubes and filaments?
Re: Overhead filament feed
Nice work.
What are the connectors between PTFE feed tubes and filaments?
There's no connector.
What you see at the end of the PTFE tube is a bit of foam to wipe any dust off the filament before it feeds. It's a habit I got into a long time ago, and helps cut back how often I have to clean nozzle clogs.
Re: Overhead filament feed
Pic appears sideways on my computer- chrome/mac. It probably looks okay on others, but here's a 'fixed' version:
Re: Overhead filament feed
Thanks. It is sideways.
Re: Overhead filament feed
Thanks for posting this. Mine are also overhead so I'm glad to see a working setup.
Now, if my upgrade kit would only ship...
Re: Overhead filament feed
So now that I've got PLA and ABS pretty well dialed in on my MMU2, I'm working on getting the kinks out of TPU.
And I've discovered a problem with using TPU and overhead filament feed: the TPU is slippery enough, and the PTFE tubes weigh enough, that occasionally the filament will slip backwards just a bit in the load sequence and fail to load.
The problem occurs at the moment when the MMU disengages the loaded filament but the bondtech has not started moving yet. Sometimes the TPU slips a couple cm, and the filament fails to load properly. Often it will load the next time.
I'm working on a solution; my idea at the moment is to use some string and binder clips to hold up the end of the PTFE tube and relieve the force pulling the filament out. This should work for TPU, which is floppy enough to just form a loop.
I don't have this problem with ABS or PLA because they have enough friction in the system to hold them in place when both the extruder and MMU are disengaged.
Re: Overhead filament feed
The problem occurs at the moment when the MMU disengages the loaded filament but the bondtech has not started moving yet.
That does not happen.
Current MMU firmware feeds about 20mm at the same time as the Bondtechs are feeding before the MMU releases the filament.
What I think you are experiencing are short load feeds by the MMU. This could be due to a slightly smaller pulley, but most likely the MMU pulleys are stretching the TPU which is then shrinking back after the MMU pulley and causing the short load.
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: Overhead filament feed
That does not happen.
Current MMU firmware feeds about 20mm at the same time as the Bondtechs are feeding before the MMU releases the filament.
What I think you are experiencing are short load feeds by the MMU. This could be due to a slightly smaller pulley, but most likely the MMU pulleys are stretching the TPU which is then shrinking back after the MMU pulley and causing the short load.
You are right; I took the time to watch the timing of the bondtech during the load process. I hadn't realized it does this. Thanks for pointing that out, and I'd been working under false assumptions about how the load cycle works all this time.
The overhead mount puts a lot of springiness in the input side, partly because of the weight of the tube and filament, and partly because the PTFE tube flexes upward to pull on the filament reel. What I'm observing is that sometimes during the load cycle when the MMU disengages the filament visibly pops back a few cm. Obviously it's not engaged at the bondtech at that point as it should be, and that must be a short load. But it's only doing that with TPU, not PLA or ABS.
It looks like the consistent back-force from the overhead mount is causing the TPU to underfeed just enough that it sometimes doesn't make it to the bondtech.
In any case, I seem to have solved the problem by hanging the end of the PTFE tube from a string. This removes most of the force pulling the filament backwards during the load cycle, and makes the whole system a lot stiffer.
Re: Overhead filament feed
nice to see the printer has left the dinning room 😀
I have a Prusa,therefore I research.
Re: Overhead filament feed
It looks like the consistent back-force from the overhead mount is causing the TPU to underfeed just enough that it sometimes doesn't make it to the bondtech.
I was testing with TPU 87A; I think I only had about 1 in 3 managed to load. I have amended the MMU firmware which should improve matters, but have not had chance to retest.
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: Overhead filament feed
I was testing with TPU 87A; I think I only had about 1 in 3 managed to load. I have amended the MMU firmware which should improve matters, but have not had chance to retest.
I'm using 92A, so a little harder. It's working well for me now that I've eliminated most of the pulling from the feed. Maybe that extra hardness is what is making the difference for me.
What change are you testing in the firmware?
Re: Overhead filament feed
I'm trying overhead as well. Nothing's working yet, so don't get too excited.
I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list.
Re: Overhead filament feed
Dear friends, just like to reach out to all of you for help regarding short loads in the overhead configuration.
Currently I print exclusively PETG and filaments 1 and 4 load. However 2 and 3 just fall short slightly (probably 5mm or less) of the extruder bondtech gears. Wonder if there is any way to ensure that they get loaded? PETG should not be as slippery as TPU.
I have tried the bowden length calibration to no avail (it keeps trying it on filament 1, any way to switch it to filament 2 and 3?). Have activated the filament sensor too.
Ideas? (= thanks in advance!
Re: Overhead filament feed
Totally with you. I make changes on the first filament, but it doesn't seem to make a difference to what gets used.
Instead of option 4 in the secret menu, you can use option 1. That lets you move the head around and "load" (spit filament to sensor then retract small amount) any filament, which I think may be the problem with my calibration, starting with the filament advanced.
I can't get back into bowden tube tuning after being in the material select stage.
I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list.
Re: Overhead filament feed
Currently I print exclusively PETG and filaments 1 and 4 load. However 2 and 3 just fall short slightly (probably 5mm or less) of the extruder bondtech gears. Wonder if there is any way to ensure that they get loaded? PETG should not be as slippery as TPU.
Sort the hobbed pulleys based on diameter of the hobbed section, smallest to position 1 and recalibrate.
Re: Overhead filament feed
Currently I print exclusively PETG and filaments 1 and 4 load. However 2 and 3 just fall short slightly (probably 5mm or less) of the extruder bondtech gears. Wonder if there is any way to ensure that they get loaded? PETG should not be as slippery as TPU.
Sort the hobbed pulleys based on diameter of the hobbed section, smallest to position 1 and recalibrate.
Thanks for this. The Hobbed pulleys are of different diameter?! No mention of this in the manual. Thought all the pulleys are of the same diameter...
Re: Overhead filament feed
What change are you testing in the firmware?
Mainly playing with the loads and preventing filament damage - which I believe is a contributor to missed layers. There's a lot to this that I don't have the opportunity to explain 🙁
As you know I don't run Slic3r, so I have to opportunity to tune the loads and unloads as much as I like and very easily. Plus amending and compiling MMU firmware is relatively straight forward.
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: Overhead filament feed
What change are you testing in the firmware?
Mainly playing with the loads and preventing filament damage - which I believe is a contributor to missed layers. There's a lot to this that I don't have the opportunity to explain 🙁
As you know I don't run Slic3r, so I have to opportunity to tune the loads and unloads as much as I like and very easily. Plus amending and compiling MMU firmware is relatively straight forward.
Peter
We certainly appreciate your contributions! Better firmware is more valuable than Slic3r changes because it helps everyone, not just people who use Slic3r.