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abraham.m
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Re: MMU2 Troubleshooting

Sep 26, 2018 10:57 pm

DavaD wrote:
Sep 23, 2018 9:57 am
Hi
I've same problem of filament load, I did the calibration load only once, I read here that need to be 3 time load and unload... Is this right? In another way it doesn't save? I've this problem every time I restart printer.
You do HAVE to press the center button to unload it. The value is saved when you perform that operation.
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jan-peter.b
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Re: MMU2 Troubleshooting

Oct 23, 2018 8:50 pm

Hello,

I have problem with my MMU2.
Filament 1 prints just fine, but when unloading it gets stuck inside the extruder due to mushrooming on the end of the filament.


1. Where the blockage occurred (in cooling tube, below cooling tube etc)


Within the extruder (the regular one, not one of the MMU extruders). The tip of the filament manages to get back above the bondtech gears but will get stuck at the opening to the PTFE tube leading to the extruder cover.

2. When the blockage occurred (load/unload)


During unloading.

3. Which extruder blocked and the previous extruder used in the print.


Extruder 1.

4. What filaments (make and colour) you were using in each extruder and the temperatures you were using.


https://shop.prusa3d.com/en/filament/22 ... t-1kg.html
at 215°C.

The second extruder is loading Geetech PLA white and should print at 215°C.
But as it can't unload Ex1...




And one smaller question: Is it normal that, at the beginning of the print, the selector moves to position 4 and pushes out ca. 10cm of Filament 1 with the message "remove old filament"?
I then have to cut it down so the selector can move again.

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PJR
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Re: MMU2 Troubleshooting

Oct 23, 2018 9:26 pm

jan-peter.b wrote:
Oct 23, 2018 8:50 pm
Hello,

I have problem with my MMU2.
Filament 1 prints just fine, but when unloading it gets stuck inside the extruder due to mushrooming on the end of the filament.


1. Where the blockage occurred (in cooling tube, below cooling tube etc)


Within the extruder (the regular one, not one of the MMU extruders). The tip of the filament manages to get back above the bondtech gears but will get stuck at the opening to the PTFE tube leading to the extruder cover.

2. When the blockage occurred (load/unload)


During unloading.

3. Which extruder blocked and the previous extruder used in the print.


Extruder 1.

4. What filaments (make and colour) you were using in each extruder and the temperatures you were using.


https://shop.prusa3d.com/en/filament/22 ... t-1kg.html
at 215°C.

The second extruder is loading Geetech PLA white and should print at 215°C.
But as it can't unload Ex1...




And one smaller question: Is it normal that, at the beginning of the print, the selector moves to position 4 and pushes out ca. 10cm of Filament 1 with the message "remove old filament"?
I then have to cut it down so the selector can move again.

Hi

Sounds as though ramming needs to be reduced.

No, that is not "normal" behaviour.

There is a sliced "Gustav the Turtle" in this post: general-discussion-announcements-and-re ... ml#p112886 Can I suggest that you try printing it?

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.

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abraham.m
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Re: MMU2 Troubleshooting

Oct 23, 2018 10:07 pm

What determines how much filament is fed to load the head?

In the g-code, each type is called out, however during the course of a print, the MMU may well be reset.

After a reset, I notice my loads/unloads are much less reliable than before it.

I already have an (unconfirmed) theory that the bowden tube length which is calibrated is multiplied by a filament type based factor. My suspicion is that this number is sent to the MMU and then later forgotten by it upon reset.

I don't know how to tell if this is true. Can you enlighten me>?
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PJR
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Re: MMU2 Troubleshooting

Oct 24, 2018 7:51 am

abraham.m wrote:
Oct 23, 2018 10:07 pm
What determines how much filament is fed to load the head?
A set number of pulley steps plus/minus any calibration adjustment.
abraham.m wrote:
Oct 23, 2018 10:07 pm
In the g-code, each type is called out, however during the course of a print, the MMU may well be reset.

After a reset, I notice my loads/unloads are much less reliable than before it.
There is no reason for this, but resetting the MMU during a print is not really a good idea; I have never tried doing that, it could upset something somewhere :(
abraham.m wrote:
Oct 23, 2018 10:07 pm
I already have an (unconfirmed) theory that the bowden tube length which is calibrated is multiplied by a filament type based factor.
I don't believe that to be the case
abraham.m wrote:
Oct 23, 2018 10:07 pm
My suspicion is that this number is sent to the MMU and then later forgotten by it upon reset.
It's not forgotten; just not used anywhere in the code.
abraham.m wrote:
Oct 23, 2018 10:07 pm
Can you enlighten me>?
I can try :)

Peter

P.S. Abraham, have you tried printing my Gustav G-code? I would appreciate some feedback on that.
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.

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Re: MMU2 Troubleshooting

Oct 24, 2018 2:22 pm

On the video from Chris I noticed it's easy to loose the the bolts and spring from the tumbler hatch.
How about adding a small nylon washer that's a holding the bolt in place if possible in the design?

After 4:35

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PJR
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Re: MMU2 Troubleshooting

Oct 24, 2018 2:24 pm

Jasper wrote:
Oct 24, 2018 2:22 pm
On the video from Chris I noticed it's easy to loose the the bolts and spring from the tumbler hatch.
Surely that only happens to Chris :) No-one else is that clumsy ;)

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.

Jasper
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Re: MMU2 Troubleshooting

Oct 24, 2018 4:35 pm

PJR wrote:
Oct 24, 2018 2:24 pm
Jasper wrote:
Oct 24, 2018 2:22 pm
On the video from Chris I noticed it's easy to loose the the bolts and spring from the tumbler hatch.
Surely that only happens to Chris :) No-one else is that clumsy ;)

Peter
ROFL

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abraham.m
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Re: MMU2 Troubleshooting

Oct 25, 2018 5:15 pm

Jasper wrote:
Oct 24, 2018 2:22 pm
On the video from Chris I noticed it's easy to loose the the bolts and spring from the tumbler hatch.
How about adding a small nylon washer that's a holding the bolt in place if possible in the design?

After 4:35
hardware-firmware-and-software-help-f56 ... ml#p112523
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james.m30
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Re: MMU2 Troubleshooting

Nov 07, 2018 3:59 am

Excellent write-up. This is a big help. I have filament feeding now and performed a first layer calibration with no hiccups.
Thanks Peter!

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