MK3S filament movement/jam detection?  

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mdaneman
(@mdaneman)
Estimable Member

I recently acquired an MK3S.  As I understand the filament sensor on MK3S just detects the presence/absence of filament, but not whether the filament is moving/extruding.  This is due to the fact the sensor is not looking at the filament directly, but at a magnetic shutter that moves to break the laser beam when filament is inserted.  I believe the MK3 had a sensor that looked directly at the filament directly and COULD detect movement, but was also affected by the color/reflectivity of the filament.

So, is there any mods / solutions that would detect filament no feeding and pause the print (ideally allowing to re-start after the problem is fixed, but the power-panic detection)?

I have now had 3 occasion where the extruder jammed and the printed happily continued to "print" without filament. The extruder gears continued to spin trying to feed filament and would grind the filament in half, with the lower half stuck in the PTFE tube and very difficult to extract without disassembling the hotend.  It also typically failed near the end of a long print (like 18 hours) forcing me to scrap the pieces.  If there was a jam sensor, it may have saved me a lot of wasted filament and time.

(p.s. I think I have an idea of how to improve the jamming issue, but that's another story.)

Thanks in advance for any feedback/help.

-Mike.

 

Posted : 31/08/2019 10:14 pm
Tim
(@tim-m30)
Illustrious Member

Sorry - but an 18 hour "long print" had me chuckling. 

The jam problem was present even with the sensor that could detect filament motion, and that laser detector would miss them, too.  You could rig up a filament counter like the wire length counters used in hardware stores, and if it didn't click every once in a while it could set off an alarm.  Not a satisfying answer, but knowing if the print is just using too little filament for a detector, or just sputtering random amounts, is a problem that has yet to be solved.

 

It is always wise to get more than one opinion......
Posted : 31/08/2019 11:58 pm
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