Unload filament, load filament loop  

Re: Unload filament, load filament loop

I’m having exact same issue ... very strange ...🤔

Re: Unload filament, load filament loop

I’m going to try to upgrade the firmware ... currently running 3.5.3 but 3.6 is available

Re: Unload filament, load filament loop

Hi Stefan,

is your printer a mk3 version with the old style laser filament sensor?

if it is, the filament sensors are a bit rubbish,

the Mk3S upgrade resolves the situation.

most folk turn the old filament sensor off when using Shiny filament, transparent / translucent filament or some green filament

regards Joan

Re: Unload filament, load filament loop

Thanks, Joan. I'm working on a just built MK3S from kit... was shipped last week.

That said, I disabled the filament sensor and it now seems to be doing my first test print just fine... not sure what the issue is with the filament sensor (seems strange to need to disable it on a latest-model printer just after installing it!)... especially when it otherwise prints the first layer test with filament sensor on and no issues.

Re: Unload filament, load filament loop

Several have reported a similar issue. Things to check:

* The magnets were installed the correct way
* the FS lever pivots freely
* the steel ball rotates freely
* the IR sensor board is neither loose nor over torqued

Someone reported that they loosened the IR sensor board and wiggled it around a bit. Don't know if that was a one off thing or something common.

Re: Unload filament, load filament loop

Hi @joan.t, I've got the mk3s. And I don't print with transparent filament. I tried with the shipped grey (or silver?) one.
Furthermore, the print while calibrating the filament thickness on board did work.
Cheers
Stefan

Re: Unload filament, load filament loop

I’m going to try to upgrade the firmware ... currently running 3.5.3 but 3.6 is available

Hi @david.043, did upgrading of the firmware help?

Re: Unload filament, load filament loop

Here's the official page for troubleshooting on this problem: https://help.prusa3d.com/article/43mduc4zdn-filament-change-prompted-at-the-beginning-of-the-print .

I turned off the filament sensor and I finally can print my first object. Hurray.

Afterwards I'm going to go through the chapter "How to fix this".

Re: Unload filament, load filament loop

I've got the same issue on a MK3S kit I built at the weekend.

I did the XYZ and first layer test with perfect results.

Then I turned it off with the PLA still loaded, tried it yesterday and the PLA came out a bit stringy, so I took the PLA out and tried to reload it and it won't go back in, just getting unload/load filament loop.

I'll try the advice here to turn off the sensor to see if that helps.

Re: Unload filament, load filament loop

I have pretty much the same problem - newly assembled MK3S. Initial calibration, including setting Z level went fine. Autoloading works. But when I try to print from the SD card, it goes into this unload/load loop. I will also check out the troubleshooting steps.

Re: Unload filament, load filament loop

Big sigh - even though I was SURE I had all the connectors right, and I DID have the IR sensor in the bottom slot, I also had it reversed. Works much better now!

Re: Unload filament, load filament loop

@stefan ... no, the firmware upgrade did not work 🙁 ... still operating with a disabled filament sensor. Thanks for posting the other thread I will look through that at next opportunity

I’ve ordered the multimaterial upgrade which I think comes with a new and different filament sensor ...

Re: Unload filament, load filament loop

Big sigh - even though I was SURE I had all the connectors right, and I DID have the IR sensor in the bottom slot, I also had it reversed. Works much better now!

---- SOLVED !!! ----

@holmes, thanks for posting this... this is exactly what I had done wrong. Good grief! I turned the IR sensor around which I had reversed just like you had.... Now that that's fixed it is printing well with the filament sensor turned on.

😀

Re: Unload filament, load filament loop

I am experiencing the unload/load loop. I inspected the IR sensor and it required some alignment to consistently read 1 with filament loaded. Although the sensor is working it still loops. Running latest software 3.7.0. I only discovered the problem when I turned on the filament sensor which was set to off as the default. Prints fine when disabled so I can live with it for now but it is annoying to spend money on the extruder update kit, do the work and have it non-functioning. I really don't want to disassemble the extruder but looks like I may have to even though I took extreme care assembling to try and avoid issues. Any other suggestions or solutions?

Re: Unload filament, load filament loop

How do you know the sensor is working? Are you viewing the sensor status display while you feed in or pull out a piece of filament?

Re: Unload filament, load filament loop

I followed the troubleshooting guide and disassembled the extruders as instructed. To diagnose the printer is on and reading the IR sensor state. I discovered that the IR sensor was unstable, changing state with minor movement of the filament. I checked everything and finally resorted to re-printing the IR lever arm and the little adapter that holds the steel ball. I replaced both parts and problem solved. The sensor reports a stable 1 when loaded and 0 when unloaded. If it is of interest, I printed the parts originally with a non-Prusa PTEG filament. I printed the replacement parts with the Prusa filament supplied in the kit. Also of note, the new parts were printed with the updated extruder which appears to make more consistent and smoother parts. Auto-load feature is working perfectly and no more loading "loop". If you are experiencing this problem I suggest you reprint the two key parts and replace yours and see what happens.

Re: Unload filament, load filament loop

I have danke problem with a printer that's been fine for months, after I updated the firmware. 3.7 has a bug.

RE: Unload filament, load filament loop

I had the same unload-load filament loop problem, but I discovered that I put the IR cable in backwards into RAMBo board: the red and black wire should be to the right; I had them to the left. 

RE: Unload filament, load filament loop

Just had the same problem. Turns out I had the filament sensor plugged into the top row instead of the bottom row.