IR sensor toggling 0-1 while printing  

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Jasper Lisabeth
(@jasper-lisabeth)
New Member

When printing from SD-card, everything goes fine for a good hour. Suddenly, the extrudor stops extruding the filament, but the printer continues to move its axes like it's printing normally. Also the extrudor-motor keeps rotating, but no filament comes out of the nozzle.

While the printer is still 'printing', without extruding filament, the IR-sensor toggles between 0 and 1. this only happens when printing from SD-card.

When I stop the print, and check the IR-sensor by placing a filament in and out of the extrudor, the IR-sensor stops toggling between 0 and 1 and behaves normally like it should.

what could the problem might be?

Video prusa 2

Posted : 19/03/2021 12:13 pm
EJTH
 EJTH
(@ejth)
Eminent Member

If the sensor toggles state randomly when there is no filament inserted, you need to recalibrate you IR sensor (again?). You have it too close this time! 

Sensor calibration (both FINDA and IR) is kind of tricky, but once you get it set and properly secured it shouldnt be a problem.

Is there any movement or noise from the extruder when in this state? I had my bondtech gear come loose from the idler once, and that caused the gears to skip so the idler would jump and intermiddently trigger the IR sensor... If you have wierd noises from the extruder, then check inside the extruder that everything is as it should be, remove the idler retainer screw and the hinge screw, remove idler and inspect the gears are secured properly, aligned and meshing fine.

This post was modified 3 months ago by EJTH
Posted : 20/03/2021 12:07 pm
EJTH
 EJTH
(@ejth)
Eminent Member

Other than that. If the filament is feeded to the extruder fine, but catches somewhere and stops extruding you should check your idler tension both on the extruder and on the MMU, it should be set as loose as possible (while still driving the filament of course).

 

If you set the idlers too tight, filament will be squished and get caught so it will not extrude, the idler gears will grind a pit in your filament and you will have to remove that broken piece.

This post was modified 3 months ago 2 times by EJTH
Posted : 20/03/2021 12:13 pm
EJTH
 EJTH
(@ejth)
Eminent Member

Remember that IR and Finda sensor calibration should be performed with the 1.5mm allen key and not a piece of filament!

This post was modified 3 months ago by EJTH
Posted : 20/03/2021 12:17 pm
Clarmrrsn
(@clarmrrsn)
Honorable Member
Posted by: @jasper-lisabeth

When printing from SD-card, everything goes fine for a good hour. Suddenly, the extrudor stops extruding the filament, but the printer continues to move its axes like it's printing normally. Also the extrudor-motor keeps rotating, but no filament comes out of the nozzle.

While the printer is still 'printing', without extruding filament, the IR-sensor toggles between 0 and 1. this only happens when printing from SD-card.

When I stop the print, and check the IR-sensor by placing a filament in and out of the extrudor, the IR-sensor stops toggling between 0 and 1 and behaves normally like it should.

what could the problem might be?

Video prusa 2

Another thing to check is cables, make sure that none of the cables are pinched anywhere.  Could be that when the x axis is moving the filament sensor cable is being stretched, or is pinched somewhere and making/breaking.  It is rather a thin cable and there are many opportunities to trap it.

The cables must be run precisely as the manual describes, particularly when assembling the extruder, and mounting the rear plate on the extruder, If a recalibration does not fix it that's a likely cause.

Check the einsy box as well, make sure there are no tight/trapped cables.

Tank you very much!...
Posted : 20/03/2021 12:22 pm
EJTH liked
Clarmrrsn
(@clarmrrsn)
Honorable Member

Apologies, was this happening only after installing MMU2s? I did not notice this was posted in the MMU2 section.

Does it do this when just the mk3 is running on its own?

Tank you very much!...
Posted : 20/03/2021 12:47 pm
HeneryH
(@heneryh)
Estimable Member

There is a known problem/design-weakness in the way the MK3S filament sensor is designed.  You may need to take the cover off and fiddle with the placement or many of us put a shim under the sensor board.

At idle, go to the sensor display LCD menu and watch the sensor value as you insert/remove the filament.  It should accurately go between 1/0.

I needed a shim to make it stable.

The MK3S+ redesigned the sensor design to make it more reliable.

Posted : 20/03/2021 4:35 pm
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