brandon.g
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MMU Gear Chewing Up Filament

Dec 04, 2018 4:54 am

I'm not sure if this is happening during loading or unloading, but the MMU bondtech gear is chewing up the filament, producing a significant amount of confetti.
IMG_20181130_214349.jpg
IMG_20181130_214349.jpg (341.41 KiB) Viewed 374 times
Has anyone else seen this and know how to address it? I recalibrated the bowden length multiple times following the individual filament calibration guide, I'm using amazon branded pla filament with default settings.

It printed these without issue while producing that amount of confetti so it's not impacting printing, but having to vacuum up after any long print job is not ideal.
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toaf
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Re: MMU Gear Chewing Up Filament

Dec 04, 2018 6:08 am

I would mess with the tension screws, and make sure the filament has a clear path, the fact its on all of them maybe look into the cap of the extruder

hey just thought of this. check and make sure that part that holds down the 5 PTFE tubes isn't too tight.
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therefore I research.
toaf.

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PJR
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Re: MMU Gear Chewing Up Filament

Dec 04, 2018 8:45 am

Set "Loading speed at the start" to 19 mm/s

Peter
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toaf
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Re: MMU Gear Chewing Up Filament

Dec 04, 2018 8:46 am

thought they fixed that in firmware?
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therefore I research.
toaf.

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PJR
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Re: MMU Gear Chewing Up Filament

Dec 04, 2018 9:09 am

toaf wrote:
Dec 04, 2018 8:46 am
thought they fixed that in firmware?
Latest MMU firmware from GitHub, just now:

Code: Select all

void load_filament_inPrinter() { // loads filament after confirmed by printer into the Bontech pulley gears so they can grab them uint8_t current_running_normal[3] = CURRENT_RUNNING_NORMAL; uint8_t current_running_stealth[3] = CURRENT_RUNNING_STEALTH; uint8_t current_holding_normal[3] = CURRENT_HOLDING_NORMAL; uint8_t current_holding_stealth[3] = CURRENT_HOLDING_STEALTH; if (isIdlerParked) park_idler(true); // if idler is in parked position un-park him get in contact with filament set_pulley_dir_push(); //PLA tmc2130_init_axis(AX_PUL, tmc2130_mode); for (int i = 0; i <= 320; i++) { if (i == 150) { if(tmc2130_mode == NORMAL_MODE) tmc2130_init_axis_current_normal(AX_PUL, current_holding_normal[AX_PUL], current_running_normal[AX_PUL] - (current_running_normal[AX_PUL] / 4) ); else tmc2130_init_axis_current_stealth(AX_PUL, current_holding_stealth[AX_PUL], current_running_stealth[AX_PUL] - (current_running_stealth[AX_PUL] / 4) ); } do_pulley_step(); delayMicroseconds(2600); } //PLA if(tmc2130_mode == NORMAL_MODE) tmc2130_init_axis_current_normal(AX_PUL, current_holding_normal[AX_PUL], current_running_normal[AX_PUL]/4); else tmc2130_init_axis_current_stealth(AX_PUL, current_holding_stealth[AX_PUL], current_running_stealth[AX_PUL]/4); for (int i = 0; i <= 450; i++) { do_pulley_step(); delayMicroseconds(2200); } park_idler(false); tmc2130_disable_axis(AX_PUL, tmc2130_mode); }
Still the same delays between steps. the 2,600 delay generates 380 steps/second at 1/2 stepping = 19mm/s for about 7.5mm, then 2,200 delay generates about 450 steps/second at 1/2 stepping = 22.5mm/s for about 22.5mm, but at much lower current, allowing the MMU drive pulleys to be puled rather than skip.

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 or loss.

alexander.i4
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Re: MMU Gear Chewing Up Filament

Dec 05, 2018 4:41 am

Dear all
I am a complete beginner, no knowledge about firmware and stuf, but what I see on my filament is that there is a litte piece of filament "bitten" everey 3 to 5 cm or so, additionlay there is clearly a feelon the filament that on one side tooth-gear has cut into the plastic.
Did I tighten my MMU2 to hard or is this a genereal assambly error by
What can I do?

Sascha

alexander.i4
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Re: MMU Gear Chewing Up Filament

Dec 29, 2018 10:50 am

Dear Brandon

Same issue here Image.
Please beware that FINDA -Holder will have filament residues inside either, you have to clean this too
Maybe you should tighten the selector with less force seemed to work for me, even now I have some Filament loading issues

sascha

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nikolai.r
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Re: MMU Gear Chewing Up Filament

Dec 29, 2018 10:45 pm

brandon.g wrote:
Dec 04, 2018 4:54 am
I'm not sure if this is happening during loading or unloading, but the MMU bondtech gear is chewing up the filament, producing a significant amount of confetti.
1. Run for each tube a length calibration
2. Set the "Loading speed at the start" to something between 15-20mm/s
3. Update the MMU/MK3 firmware and Slic3r (don't forget to reset the filament configurations) to the most recent version

After this steps grinding should disappear.

daniel.k17
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Re: MMU Gear Chewing Up Filament

Dec 30, 2018 9:02 am

For me it grinds during the fast unload session, the fast load is smoth and nice

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