FS-Lever Not Clearing Filament IR Sensor (Auto Load Failure)
 

FS-Lever Not Clearing Filament IR Sensor (Auto Load Failure)  

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ben_r_
 benr
(@benr)
Trusted Member

After a fun 8.5 hours of build time my new i3 MK3S printed several items perfectly! Everything was going well until I tried to load a new color filament into the extruder.

First sign of the problem was the Auto Load Filament feature was not working. So after reading a bot online I found that I could find out if the IR sensor was working properly and I have confirmed that it is. It correctly reads something obstructing its path.

After slowly taking bit by bit off the extruder I discovered the issue. The FS-Lever (LINK) is not moving enough and is always blocking the path of light for the IR sensor. So the printer always thinks there is already filament loaded and will not auto load.

Going through the calibration process and manually loading filament works perfectly, so I knot there is nothing wrong with the extruder otherwise. I can also confirm that the magnets in the extruder body and FS-Lever function as they should and the Steel Ball Assembly (LINK) seems to work as it should.

It just just appears that the FS-Lever isnt moving far enough towards the Steel Ball (or the Steel Ball isnt moving enough) to have the back part of the FS-Lever clear the IR sensor letting the controller know there is no filament loaded.

Anyone else have this issue or has had it and know what I did wrong? Also, in the menu options I only see the ability to turn the Auto Load Filament feature on. But where is the Manual Load Filament option? Running firmware 3.7.2 if that helps.

If at first you don't succeed, redefine success!...
Posted : 26/08/2019 6:52 pm
florian liked
ben_r_
 benr
(@benr)
Trusted Member

Hmmm.... perhaps this is the same issue Im having: LINK
Video here demostrates it well: LINK

If so, is that a flaw in the design of the extruder body?

If at first you don't succeed, redefine success!...
Posted : 26/08/2019 7:18 pm
ben_r_
 benr
(@benr)
Trusted Member

So for now, just so I can continue enjoying my new printer and dont start blaming Prusa for what appears to be a design flaw in the filament sensor design, I have disabled the Auto Load Filament feature and Filament sensor.

Now Im wondering, if I leave those disabled will that interfere with the MMU2S? I am planning on ordering the kit next week but I need to know if Ill need to get this filament sensor working before I can use the MMU2S.

If at first you don't succeed, redefine success!...
Posted : 27/08/2019 2:35 am
david.a66
(@david-a66)
Honorable Member

the mmu2s replaces the filament sensor design with a new idler door and sensor mount/tower

Posted : 27/08/2019 3:09 am
ben_r_ liked
ben_r_
 benr
(@benr)
Trusted Member
Posted by: david.a66

the mmu2s replaces the filament sensor design with a new idler door and sensor mount/tower

Awesome! If thats the case then I dont have to worry about spending hours tearing down the extruder just to fix this design flaw! Glad I asked. Ill just leave the Auto Load Filament feature and IR Filament Sensor disabled until my MMU2S comes then replace it with whatever that brings!

If at first you don't succeed, redefine success!...
Posted : 27/08/2019 3:41 am
Afro Samurai
(@afro-samurai)
Active Member

yes.. i am having the same problem.. but it worked when first assembled.. for but then shortly after.. it stopped working.. 

I can check the sensor feed.. and no matter what i do.. filament in or not. the sensor value is still at "1"... 

 

Was thinking on getting a new sensor..but will try shaving a bit of the lever off as you did.. maybe something moved.. not sure.. but for a while now i have just been running it.. since it doesnt affect anything.. just kind of sucks not having auto load and any alarms enabled.. 

will try shaving a bit of the lever off..will print a few spares.. 

This post was modified 12 months ago by Afro Samurai
Posted : 01/09/2019 9:00 pm
ben_r_
 benr
(@benr)
Trusted Member
Posted by: lmbee2013

yes.. i am having the same problem.. but it worked when first assembled.. for but then shortly after.. it stopped working.. 

I can check the sensor feed.. and no matter what i do.. filament in or not. the sensor value is still at "1"... 

 

Was thinking on getting a new sensor..but will try shaving a bit of the lever off as you did.. maybe something moved.. not sure.. but for a while now i have just been running it.. since it doesnt affect anything.. just kind of sucks not having auto load and any alarms enabled.. 

will try shaving a bit of the lever off..will print a few spares.. 

Yea I didnt do anything with it. After learning that the IR filament sensor is no longer used once the MMU2S is installed I just left it as is. I have the MMU2S on order and once that gets installed I wont be using the current IR filament sensor anyway.

If at first you don't succeed, redefine success!...
Posted : 02/09/2019 4:48 am
joan.t
(@joantabb)
Veteran Member Moderator

the new style IR Sensor is re purposed in the Mk2s/MMU2S solution
the steel ball is removed along with it's housing, the FS lever becomes redundant and the filament sensor is moved to the top of a new tower assembly where the extended arm on the Bondtech idler door becomes the  filament sensor actuation tab. 

The Mk3S/ MMU2S senses the filament leaving the Filament selector, using the Finda, and waits for it to arrive at the printer, using the IR Filament sensor to display success, the MMU then disengages, letting the extruder bondtech hobbed gears tke over control of the filament movement. 

so if you have abandoned the IR sensor temporarily, you are ok but if you think the IR Sensor is dead and buried, you are in error. 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 02/09/2019 8:31 am
david.a66 liked
shadewind
(@shadewind)
Active Member

I have this exact problem and it seems like a design issue. As soon as I put the extruder body back on, it turns to 1 permanently. As some others have said, putting a spacer between the sensor and the body solves the issue for me but I'd rather have it fixed in the actual original part...

Posted : 02/09/2019 2:14 pm
florian liked
ben_r_
 benr
(@benr)
Trusted Member
Posted by: shadewind

I have this exact problem and it seems like a design issue. As soon as I put the extruder body back on, it turns to 1 permanently. As some others have said, putting a spacer between the sensor and the body solves the issue for me but I'd rather have it fixed in the actual original part...

Yea its a flaw in the design. Nothing more can be said for it except trying one of the various ways to work around the issue or fix it. As I mentioned before I just disabled Autoload Filament as manual loading is fine for me for now. Once the MMU2S comes in a few days I wont have to worry about this setup anymore. I have confirmed that my IR sensor is working fine though, its just a poor design in the FS-Lever and the extruder housing parts around it.

If at first you don't succeed, redefine success!...
Posted : 02/09/2019 5:59 pm
ronsukalac
(@ronsukalac)
New Member

I had this problem and tried various fixes. Adding the washer under the sensor made it almost work (intermittently) but the sensor really needed to shift to the left (when facing the front of the unit) to be further away from the flag. I ended up removing the sensor board and sanding off a bit from the left edge of it and then opening up the mounting hole to allow some play in it. I pushed the board to the left as I tightened it down and it was enough to apparently make it work reliably. I did a hot test printing with a short piece of filament. The printer then correctly reported filament out and allowed me to eject and put in a new one to complete the print. Hopefully this will hold up over time. If you try this, be careful to not get close to any board traces when trimming or drilling. It only needed a small amount of movement to get it working.

Posted : 12/01/2020 10:45 pm
mierendorffplatz
(@mierendorffplatz)
Active Member

Glad to hear we all have the same problem 😉 

Not knowing it was a design flaw I loaded my filament by shortconnecting the Sensor Pin + and OUT for half a year now 🤣 

And PRUSA does nothing?

Posted : 12/04/2020 3:55 pm
rogerfortney
(@rogerfortney)
New Member

I found out I have the exact same problem for the exact same reason after having to remove stuck filament because runout cant be detected.  Wish they would fix the design of the fs-lever.  As it is currently designed I don't even understand how it could ever work right and capable of passing the test phase of it's design.  It couldn't have worked with this design.

Posted : 02/06/2020 6:18 am
keelyarnett
(@keelyarnett)
New Member

I was having the same issue.  Added three washers and it works fine.  I was trying to find a small spring or rubber washer to make the height adjustable.  I didn't have any that would fit and just added one washer at a time until it read correctly and consistently.  With the screw tightened the IR was too low and was always "1".  The washers brought it up so it's "0" without filament loaded.  Tested and it's been working much better.  The play that causes it to shift left or right doesn't seem to affect mine.  I've only had my kit assembled and running a few days, but will see how this works out long term...I still want to find a spring to be able to adjust it easily when things 'settle'. 🙂  I don't know 3d design all that well yet.  I want to remix the cover so there's a hole for adjustment and add room for a spring.

Posted : 29/07/2020 12:39 am
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