Pulley Motor Stalls
Hi,
I encounter the problem that the pulley motor stalls sometimes when retracting the filament from the extruder to the MMU.
Observations:
- My MMU has many modifications, but the pulley part is mostly unchanged.
- Initially, I used clone components, but I upgraded to the original pulley motor.
- After swaping the motor to the genuine part, it did ont happen for quite a while, now it happened 2 times within 2 days. (Maybe still random since I did not print very much after swapping)
- When a stall occurs, I can pull on the filament. After I overcome a resistance, the the motor rotates again and the MMU will continue operation.
- I recreated the stall when driving the motor with a standalone stepper motor driver. It happened above a certain speed (only when the the speed is beyond a certain thershold and each time when going beyond the threshold). It also happened when the motor was outside the MMU and nothing attached to it.
- My MMU is mounted outside of the printer enclosure. Its orientation is such that the pulley axis points up.
- Before upgrading to MMU3, I used the stealth mode to prevent stalls. I think the lower retraction speed is key.
Is there anyone who encountered this problem, too?
I mostly guess that I damaged both motors, but I am not sure how.
Do you have ideas for the reason? Maybe the orientation lead to higher wear in bearings? Or what else could damage the motor? Maybe the reason is something totally different?
Is there a way to set the retraction speed of the MMU?
RE: Pulley Motor Stalls
I am having the exact same issue and it is driving me nuts. I've tried everything.
I am wondering if you tried increasing the current of the pully motor? It seems to have a lower current than the other steppers and there is a way to do it here: https://help.prusa3d.com/article/registers-mmu-mmu3_511780
RE: Pulley Motor Stalls
Have you the O-Ring installed? It takes a lot of power from motor?
Motor Stall I only recognized if idler tension is to strong, maybe because there blocks anything the lever from reaching the filament with bearings and pushes the mainplate to the PG wheel
My Printables models including Nextruder improvements: https://www.printables.com/@ThorstenLach_1801966
RE: Pulley Motor Stalls
Oh, I missed that there was a reply!
@Kinchey,
Do you have the original MMU3? Clone Components? Some modifications?
I have a workaround that helps 98% of the time. I reduce the Pulley speed with a custom g-code.
this is part of my Start G-code:
M862.6 P"Input shaper" ; FW feature check
M862.6 P "MMU3" ; FW feature check
M115 U6.1.3+7898; setup MMUM
708 A0x1e X12 ; Pulley current to ~200mA
M708 A0x0d X40 ; Pulley_unload_feedrate default: 120
M708 A0x11 X40 ; Pulley_load_feedrate default: 80
not sure what I added, maybe only the last two lines are relevant.
@thorsten-lachmann:
I have to look up which O-Rings you are referring to. So I guess I don't have them.
Mechanical tension sounds like a reasonable explaination. However, I get the issue also, when I operate the motor after removing it from the MMU.
There is no tension, and also no filament to pull. That's why I rather think it is not the reason.
I could think of too much tension causing wear, though.
RE: Pulley Motor Stalls
In your Start code there is a line break wrong, but I assume that is only copy paste issue.
by default this is the MMU register setup in the start code:
; setup MMU M708 A0x0b X5 ; extra load distance M708 A0x0d X140 ; unload feeedrate M708 A0x11 X140 ; load feedrate M708 A0x14 X20 ; slow feedrate M708 A0x1e X12 ; Pulley current to ~200mA
40 as load and unload seems to be slow.
personally I tweaked my MMU setup in the startcode
M708 A0x0b X0 ; extra load distance TL: removed not needed extra load M708 A0x0d X180 ; unload feeedrate TL: speed up unload M708 A0x11 X180 ; load feedrate TL: speed up load M708 A0x14 X30 ; slow feedrate TL: Speed up slow feedrate ;M708 A0x1e X12 ; Pulley current to ~200mA M708 A0x1e X20 ; Pulley current to ~350mA TL mod M708 A0x23 X40 ; Cut length to 25mm TL extend cut length
The pulley motor is rated to 1A, so 350mA is okay for me, on my side it seldom happens that pulley motor stalls, but then there happens a reason like the filament tip is bad and hits a edge and blocks or if at spool a blocking happens.
Can you use a terminal to comunicate with printer like octoprint? then you can check how the MMU is configured when using M707 instead M708 with the corresponding address above e.g.
M707 A0x1e to read the configured pulley current.
Does the issue also appears if you power up the printer and using UI to do Load-Tests or to perform load to Nozzle Filament? because after power up custom gcode didn´t have influence and only Eeprom config is used.
My Printables models including Nextruder improvements: https://www.printables.com/@ThorstenLach_1801966
RE: Pulley Motor Stalls
In your Start code there is a line break wrong, but I assume that is only copy paste issue.
yes. The forum removed all line breaks...
40 as load and unload seems to be slow.
it is. i wanted to be sure to prevent stalls. For a long time, i could reproduce that it happened only at fast feedrates.
but then there happens a reason like the filament tip is bad and hits a edge and blocks or if at spool a blocking happens.
I don't think this is the problem in my case. I was easily able to pull out the filament. Also many times it stalled while the end was in the middle of the bowden tube.
Does the issue also appears if you power up the printer and using UI to do Load-Tests or to perform load to Nozzle Filament? because after power up custom gcode didn´t have influence and only Eeprom config is used
Never seen it, but I rarely use that function.
Can you use a terminal to comunicate with printer like octoprint? then you can check how the MMU is configured when using M707 instead M708 with the corresponding address above e.g.
M707 A0x1e to read the configured pulley current.
I will do that at the next opportunity.