Crank sound while exchanging filament
Hello,
This is what happens on my extruder just at the time the extruder engine starts rotating when NO FILAMENT is loaded (during a filament exchange on my MMU2S)
I
What do you think could be the reason? have you had the same issue and have you solved it?
I first think about a problem in the MK3S extruder design, but after opening the pieces I don't see the walls devastated so this is not the issue.
I thought about the PTFE but it looks in good conditions and not in contact with anything.
How about the bearings inside?, note the noise only comes when no filament is loaded in the gears.
Thanks!
Best Answer by Ellswor:
So I struggled with this issue as well for a while. I was able to narrow down the sound to the interaction of the gears on each other. It wasn't caused by the PTFE tube. What eventually fixed it was following the prusa guide on Bondtech maintenance( https://help.prusa3d.com/article/3EMxwPQU0B-bondtech-extruder-gears ).
Essentially adding some lubricant to the gear teeth fixed the problem and now my gears are silent.
Hope this helps, and I really think this should have been part of the assembly instructions.
RE: Crank sound while exchanging filament
I just now had the same issue. My tiny screw from the pully was loose. I just opened the door (2 screws) and fixed the pully again.
Reason of my problem: It started when a print (single material) with low layer height started to clog my nozzle. Probably some kind of fat tip formed and got stuck in the extruder PTFE. Then the MMU2S finished the print with the top layers missing (underextusion).
When unloading the MMU2S pulled on the stuck filament - after all that I had the problem.
Another thing that I didn't like was that the MMU2S stopped the print with an unload-problem and the nozzle remained hot.
RE: Crank sound while exchanging filament
Hi, take a look on this thread, I had the same nasty noise during filament change, I did some changes to the extruder to solve it. https://forum.prusa3d.com/forum/original-prusa-i3-mmu2s-mmu2-hardware-firmware-and-software-help/loud-clicking-from-bondtech-gears-while-loading-unloading/#_ga=2.118670153.1763390156.1558804013-2006940115.1558804013
MK4/MMU3 - VORON 2.4 350 Stealthburner
RE: Crank sound while exchanging filament
Thanks Andreas-d10. I've tightened that screw and the noise is less loud but continues.
Thanks andre-I9. I'll take a look at your design.
I'm still thinking there is something wrong with the firmware. The extruder can stop moving when the IR sensor signals 0 and could start moving after the IR sensor signals 1. Current firmware keeps the extruder running fast with no reason. I'll investigate the firmware to see if I can do anything on that side.
Cheers
RE: Crank sound while exchanging filament
I'll investigate the firmware to see if I can do anything on that side.
Well,
Here are my findings up till now.
1) The Slicer produces the g-code (instructions) that tells the extruder engine to move. This means that one possible fix is to go deep inside how the PrusaSlicer is generating the G-Codes that keeps the extruder motor running when there is no filament loaded in the extruder. This is at this time my preferred solution so I'll try to report a bug on the slicer to see if I can get attention of the Prusa Development Team.
2) Another alternative is to modify the firmware so the GCodes relative to the extrusion engine are "ignored" when the IR sensor indicates there is no filament. The advantage of this solution is that even with badly generated g-code it is possible to save the printer hardware, but there might be rare cases where you may want to move the extruder even if the IR sensor indicates there is no filament loaded so there should be a software option in the menu to deactivate this protection
Both two solutions requires better documentation of the firmware and available GCodes. The official documentation here https://github.com/prusa3d/Prusa-Firmware/wiki/Supported-G-codes is "work in progress" and if you explore the generated GCode during a filament change there is something like this.
;--------------------
; CP TOOLCHANGE START
; toolchange #3
; material : PLA
;--------------------
M220 B
M220 S100
; CP TOOLCHANGE UNLOAD
G1 X229.250 Y152.480
G1 F1341
G1 X223.671 E0.2816
G1 F1452
G1 X217.626 E0.3051
G1 F1644
G1 X210.785 E0.3453
G1 F1899
G1 X202.881 E0.3990
G1 F2266
G1 X193.449 E0.4761
G1 F2745
G1 X182.025 E0.5767
G1 F3224
G1 X170.750 E0.5691
G1 Y151.700 F7200
G1 F3224
G1 X172.892 E0.1081
G1 F3639
G1 X188.036 E0.7644
G1 F3926
G1 X204.375 E0.8248
G1 F4038
G1 X221.180 E0.8483
G1 E-15.0000 F6000
G1 E-24.5000 F1200
G1 E-7.0000 F600
G1 E-3.5000 F360
M104 S215
G1 Y150.920
G1 X170.750 E20.0000 F488
G1 X221.180 E-20.0000 F326
M73 Q6 S110
M73 P6 R109
G1 E-35.0000 F2000
G1 Y151.060 F2400
G4 S0
T3
G4 S0
; CP TOOLCHANGE LOAD
G1 E12.0000 F1140
G1 X170.625 E42.0000 F1315
G1 X221.180 E6.0000 F713
G1 Y151.560
; CP TOOLCHANGE WIPE
G1 X229.000 E0.3507 F800
G1 X229.750 Y151.060 E0.0404
G1 X171.000 E2.6348 F900
G1 X170.250 Y150.560 E0.0404
G1 X229.000 E2.6348 F1100
G1 Y150.060 E0.0224
G1 X171.000 E2.6012 F2100
G1 Y149.560 E0.0224
G1 X229.000 E2.6012 F2125
G1 X229.750 Y149.060 E0.0404
G1 X171.000 E2.6348 F2150
G1 X170.250 Y148.560 E0.0404
G1 X229.000 E2.6348 F2175
G1 Y148.060 E0.0224
G1 X171.000 E2.6012 F2200
G1 Y147.560 E0.0224
G1 X229.000 E2.6012 F2225
G1 X229.750 Y147.060 E0.0404
G1 X171.000 E2.6348 F2250
G1 X170.250 Y146.560 E0.0404
G1 X229.000 E2.6348 F2275
G1 Y146.060 E0.0224
G1 X171.000 E2.6012 F2300
G1 Y145.560 E0.0224
G1 X229.000 E2.6012 F2325
G1 X229.750 Y145.060 E0.0404
G1 X171.000 E2.6348 F2350
M73 Q7 S109
M73 P7 R108
G1 X170.250 Y144.560 E0.0404
G1 X229.000 E2.6348 F2375
G1 Y144.060 E0.0224
G1 X171.000 E2.6012 F2400
G1 Y143.560 E0.0224
G1 X229.000 E2.6012
G1 X229.750 Y143.060 E0.0404
G1 X171.000 E2.6348
G1 X170.250 Y142.560 E0.0404
G1 X229.000 E2.6348
G1 Y142.060 E0.0224
G1 X171.000 E2.6012
G1 Y141.560 E0.0224
G1 X229.000 E2.6012
G1 X229.750 Y141.060 E0.0404
G1 X171.000 E2.6348
G1 X170.250 Y140.560 E0.0404
G1 X229.000 E2.6348
G1 Y140.060 E0.0224
G1 X171.000 E2.6012
G1 Y139.560 E0.0224
G1 X229.000 E2.6012
G1 X229.750 Y139.060 E0.0404
G1 X171.000 E2.6348
G1 X170.250 Y138.560 E0.0404
G1 X229.000 E2.6348
G1 Y138.060 E0.0224
G1 X171.000 E2.6012
G1 Y138.560
G1 X230.000
M220 R
G1 F6000
G4 S0
G92 E0
; CP TOOLCHANGE END
;------------------
But the documentation tells you nothing about some of the instructions in use 😕 in my little understanding of the gcode, I believe that this instructions:
G1 E-15.0000 F6000
G1 E-24.5000 F1200
G1 E-7.0000 F600
G1 E-3.5000 F360
Are responsible of moving the Extruder some mm with a determined flow.
I don't know if I can go much further... I hope someone from Prusa can continue from here.
Regards
Ignacio
RE: Crank sound while exchanging filament
So I struggled with this issue as well for a while. I was able to narrow down the sound to the interaction of the gears on each other. It wasn't caused by the PTFE tube. What eventually fixed it was following the prusa guide on Bondtech maintenance( https://help.prusa3d.com/article/3EMxwPQU0B-bondtech-extruder-gears ).
Essentially adding some lubricant to the gear teeth fixed the problem and now my gears are silent.
Hope this helps, and I really think this should have been part of the assembly instructions.
RE: Crank sound while exchanging filament
Indeed!
Thank you for the link. The indicated procedures solved the sound problem.
In any case, I don't see any reason for keeping the bondtech extruder gears rolling while there is no filament engaged so I'll leave the bug as it is in github
RE: Crank sound while exchanging filament
the extruder needs to run to grab the filament as it enters the bondtech gears. it should only be moving during the actual load cycle and not during idle time.
RE: Crank sound while exchanging filament
I agree, it should be running after the IR sensor detects the filament passing through
RE: Crank sound while exchanging filament
that doesn't work - with the mmu2 the ir sensor is triggered by the filament spreading the bondtech gears apart - so the motor has to start before the filament gets to the gears to grab the filament. at best they could wait till the finda shows filament leaving the mmu2 but right now the MMU2 does not send finda state to the einsy during a load. and the motor running is not a real issue it consumes the same power turning or stopped