Easiest way to get to filament detector on a MK3S
I finished my MK3S a few months back; it's working great except that the filament detector always thinks there is filament present.
I suspect I misassembled it (or overrightened the screw that the FS lever pivots on).
What's the easiest way to get to the FS lever detector to free that up? Putting together the FS lever was pretty early on in the printhead assembly instructions; working backwards from the end of the chapter would be painful....
It's just an annoyance, but I have the time to work on it...
Best Answer by HeneryH:
I also had trouble with the sensor and took the unit apart a few times.
Here are some hints to try before taking it apart...
Just access the sensor by removing the cover.
Loosen the sensor and play with it while inserting and removing the filament while watching the senor readout 0/1.
Hopefully you can loosen or shim under the sensor (print a little pad with a hole in it for a shim) and get it to work.
If you need to go inside the unit, perhaps loosen the screw holding the lever to make sure it moves freely.
When putting it back together... MAKE SURE THE FAN WIRE IS outside the hot end frame. Every single time I put it back together I had to do it twice because the fan wire was tucked in next to the hot end. I always got to that and yelled "D#$^%, not again!"
RE: Easiest way to get to filament detector on a MK3S
Had the same problem on the first day. I've unscrewed the filament sensor board on top by half a turn and it works fine since (it can move a little bit if needed, but still in place with the screw).
RE: Easiest way to get to filament detector on a MK3S
Here are the instructions to get at the internal mechanism
https://help.prusa3d.com/en/article/ir-filament-sensor-troubleshooting-mk2-5s-mk3s_112226
The FS lever is not moving correctly
The FS lever is the part that is moved by the filament to activate the sensor. How to access it:
-
- The first step is to toggle the Filament autoload off. Do it in the LCD Menu -> Settings -> F. autoload. (but the Fil. sensor must be still [on]!)
- Now we need to get to the filament sensor mechanism. Before you start, make sure the printer is cold and that none of the fans is spinning.
- Take the Print fan off by unscrewing both M3x20 screws holding it on the Extruder. Do not lose the nuts for these screws. You can insert the fan in between the belts on the left side, it should fit there just fine.
- Unscrew 2 out of 4 screws of the Noctua Hotend fan that are the closest to the original position of the Print fan. One of them is M3x18 (or M3x20 if you decided to use it instead) and the other one is the top-right M3x14.
- Unscrew both long M3x40 screws located below the Extruder motor and take the Extruder cover off.
- Unscrew the M3x40 screw holding the Extruder idler door as well as the other M3x40 screw holding the upper part of the assembly together.
- Take the Extruder motor off.
- You now have full access to the hotend and to the filament sensor mechanism.
RE: Easiest way to get to filament detector on a MK3S
I also had trouble with the sensor and took the unit apart a few times.
Here are some hints to try before taking it apart...
Just access the sensor by removing the cover.
Loosen the sensor and play with it while inserting and removing the filament while watching the senor readout 0/1.
Hopefully you can loosen or shim under the sensor (print a little pad with a hole in it for a shim) and get it to work.
If you need to go inside the unit, perhaps loosen the screw holding the lever to make sure it moves freely.
When putting it back together... MAKE SURE THE FAN WIRE IS outside the hot end frame. Every single time I put it back together I had to do it twice because the fan wire was tucked in next to the hot end. I always got to that and yelled "D#$^%, not again!"
RE: Easiest way to get to filament detector on a MK3S
I just had to fix mine. It wasn't that bad. I think I had a seating issue with the lever and cover.
RE: Easiest way to get to filament detector on a MK3S
The FS lever was working fine, it was just an alignment thing between the sensor and the level, just like all 3 of the respondents.
I ended up shimming it; I had some brim left over from a old print; two layers of that under the sensor as a shim got the spacing correct. Tightened it down just enough that it won't wiggle, and the sensor seems pretty reliable.
Thank all 3 of you for your responses; they saved me a lot of time and frustration.
RE: Easiest way to get to filament detector on a MK3S
I had the same problem, and the shim solution fixed it.
Thanks!