IR filament sensor stops working (mk3s + mmu2s)  

Re: IR filament sensor stops working (mk3s + mmu2s)

I thought I also calibrated the IR sensor and figured everything worked well, but turned out that even the printer vibrations were enough to trigger the sensor and make the MMU stop feeding filament. I was looking elsewhere until I found a post talking about it and how scraping away some material from the lever made this more stable. It made a world of difference to me, perhaps this might also be the problem you're having? So in my case it was not technically possible to calibrate the IR sensor reliably with the procedure as described in the manual.

Re: IR filament sensor stops working (mk3s + mmu2s)

I thought I also calibrated the IR sensor and figured everything worked well, but turned out that even the printer vibrations were enough to trigger the sensor and make the MMU stop feeding filament. I was looking elsewhere until I found a post talking about it and how scraping away some material from the lever made this more stable. It made a world of difference to me, perhaps this might also be the problem you're having? So in my case it was not technically possible to calibrate the IR sensor reliably with the procedure as described in the manual.

Thanks for your answer steve.g

My problem is just the oposite, the MMU doesn't stop feeding filament.
In any case for avoid discarting anything I tried your solution and It gotharder to calibrate the IR Sensor (I cutted a cuple of layers).

I tried unmounting the chimenei and triger the IR sensor with a allen key but it seems to be turned off and doesn't detect any change after load and unload the first filament. It seems to be working randomly.

Re: IR filament sensor stops working (mk3s + mmu2s)

Thanks for your answer steve.g

My problem is just the oposite, the MMU doesn't stop feeding filament.
In any case for avoid discarting anything I tried your solution and It gotharder to calibrate the IR Sensor (I cutted a cuple of layers).

I tried unmounting the chimenei and triger the IR sensor with a allen key but it seems to be turned off and doesn't detect any change after load and unload the first filament. It seems to be working randomly.

This is probably also related to the IR sensor, but the other way around: it's most likely not being triggered instead of too much.
Cutting material is definitely not a solution then, you need the opposite.
Have you looked on the printer in the Support menu to Sensor Info. Does the IR ever switch from 0 to 1 when you feed it filament? If not you have to look into the Calibration of the IR in the manual (section 7.1). I prefer doing it with filament instead of that alan key, but to each his own.

Re: IR filament sensor stops working (mk3s + mmu2s)

Hi steve.g

I have been touching many things and I found something interesting.

I was able to calibrate the IR sensor but depending the tension on some screws the sensor works better (both screws in the chimenei and extruder idler one).

I adjusted everything in a way that I can check (in support -> sensors) that IR is correctly triggered when I insert a piece of filament (as you suggested) and it seem to work.

The current problem is the extruder idler screw needs to be with a very low tension and the printer is under extruding.

I suppose it can be result of the modification I did in the piece so I will try to print the piece again and recheck everything.

Other things I tried:
- Check connections to the EINSY (principally IR sensor)
- Recalibrate F.I.N.D.A
- MMU2s factory reset.

I will write you back when I recheck everything with the new part.

Thank you.

Re: IR filament sensor stops working (mk3s + mmu2s)

Hi,
Finally I reprinted the "extruder-idler-mmu2s" and calibrated again the IR sensor. It seems to be working now. My original piece came on the "UPGRADE MMU2 to MMU2S with printed parts" kit, I don't know if it could be realted.

After trying to many things I don't know where was exactly the problem. If someone has any similar problem I recommend:

1 - Check the connections with "EINSY RAMBo" - https://manual.prusa3d.com/Guide/8.+Electronics+assembly/1052?lang=en
2 - Re-print "extruder-idler-mmu2s" and change - https://www.prusa3d.com/downloads/others/MMU2toMMU2S_upgrade_stl.zip
3 - Re-calibrate IR Sensor with a piece of filament - https://help.prusa3d.com/article/wprwemqsmj-ir-filament-sensor-calibration
5- Re-calibrate F.I.N.D.A - https://manual.prusa3d.com/Guide/5.+Pulley+body+assembly/1040?lang=en
6 - Factory reset of MMU2s - https://manual.prusa3d.com/Guide/Service+menu+-+Factory+Reset/871?lang=en

At this moment my mk3s + mmu2s is printing the test sheep. I will update the results.

Thank steve.g for your support.

UPDATE: Sheep finished perfect

Re: IR filament sensor stops working (mk3s + mmu2s)

I said victory to early.

As you saw printer and mmu were working perfectly.

I decided to try again the firmware 3.7 and the problem raised again.

With the firmware 3.7 it gets stuck in a while:
- mmu2s loads filament to the extruder
- filament is detected by IR sensor
- mmu2s unloads filament
- repeat

So after try to calibrate IR sensor and factory reset mmu2s again I decided to downgrade to 3.6 because the printer was working.

Now I am having some problems with filament change again (I suppose it's related to calibration) but at least filament is loaded.

Could be something related to IR sensibility in the new firmware?

Thank you

Re: IR filament sensor stops working (mk3s + mmu2s)

With the firmware 3.7 it gets stuck in a while:
- mmu2s loads filament to the extruder
- filament is detected by IR sensor
- mmu2s unloads filament
- repeat

That's a firmware problem. I too have this and have reported it to the devs. Currently reverted to 3.6 which works fine for me.

Peter

Re: IR filament sensor stops working (mk3s + mmu2s)

Hi Peter,

Thanks for your answer! It is good to know because I was getting crazy.
Do you know if there is any place where track the issue?

Thank you

Re: IR filament sensor stops working (mk3s + mmu2s)

Do you know if there is any place where track the issue?

Sorry, I don't. I find Github confusing, so I use other ways to let the devs know. It seemed to work for the fault I found in 3.7.0-RC1, so hopefully it will also work for this 😉

Peter

Re: IR filament sensor stops working (mk3s + mmu2s)

Hi Peter,

Thanks for your answer! It is good to know because I was getting crazy.
Do you know if there is any place where track the issue?

Thank you

One of these looks to be your issue on Github (not sure if they are the same problem or not):
https://github.com/prusa3d/Prusa-Firmware/issues/1689
https://github.com/prusa3d/Prusa-Firmware/issues/1700

Re: IR filament sensor stops working (mk3s + mmu2s)

One of these looks to be your issue on Github (not sure if they are the same problem or not):
https://github.com/prusa3d/Prusa-Firmware/issues/1689
https://github.com/prusa3d/Prusa-Firmware/issues/1700

They are similar issues, but the first definitely relates to the new method for preventing missed layers.

3.7.0 behaviour is for MMU to load Bondtech and trigger IR sensor, Bondtech loads 50mm then unloads 45mm and the sensor is checked to ensure filament is present. If not, only a single retry occurs.

Good in theory, but in practice, unfortunately it's a fail. Especially because the subsequent code ignores the MMU error condition and continues to print without filament 🙁

Peter

Re: IR filament sensor stops working (mk3s + mmu2s)

3.7.0 behaviour is for MMU to load Bondtech and trigger IR sensor, Bondtech loads 50mm then unloads 45mm and the sensor is checked to ensure filament is present. If not, only a single retry occurs.

Good in theory, but in practice, unfortunately it's a fail. Especially because the subsequent code ignores the MMU error condition and continues to print without filament 🙁

Peter

And...this just happened to me. Nothing but issues since I upgraded to the MMU2s and 3.7.0. Had my MMU dialed in and working beautifully and decided to upgrade. When am I going to learn to leave things that are working alone. 🙁