MK3S+ has a suddenly flaky filament sensor
I have a MK3S+ that has exhibited generally excellent performance for most of its three-year lifespan of casual use.
A few days ago, the printer paused mid-print with the message: "Press knob to unload filament." I've encountered this before during a filament runout, but this time, the filament was still loaded. I unloaded the filament and reloaded it, and the print resumed printing - but about 15 minutes later, it paused again with the same message.
Over the next few days, I repeatedly tried printing the same model with the same filament. My printer kept pausing at random points with the same message. Often, it would go through this process repeatedly and wouldn't actually resume. The problem has steadily grown worse - I can't even get through a full first layer on a relatively small part without encountering the message.
The only solution I've found is turning off the filament sensor. In that case, the printer runs just fine. But, of course, I'd like to have a working filament sensor, both for the functionality of detecting filament runout and for the convenience of autoloading filament.
Things I've tried without success:
* Switching filament spools, including entirely different types of filament from different manufacturers.
* Trying different models.
* Loosening the filament sensor door and inspecting the filament sensor.
* Loosening the idler screw and inspecting the idler.
* Running the entire printer calibration process.
* Updating the printer firmware. (I was using the second-to-latest firmware when the problem began.)
I suppose the part that I find most puzzling about this problem is that nothing changed at the time of the error. I was in the middle of printing a bunch of normal parts with normal filament and normal settings.
Any suggestions? Should I just replace the IR sensor? (And do IR filament sensors spontaneously fail like this?)
Thanks in advance.
RE: MK3S+ has a suddenly flaky filament sensor
Filament sensor door ? You must have a different special printer as the filament lever is not accessible except by partial disassembly. Its a physical lever that moves and blocks a break beam detector. Like any moving part it can get clogged with crap from filament, try cleaning it out and adjusting it. Also the break beam detector could also potentially be dirty too. You just need to clean and maintain your printer.
RE: MK3S+ has a suddenly flaky filament sensor
Filament sensor door ? You must have a different special printer as the filament lever is not accessible except by partial disassembly.
Umm.. are you familiar with the MK3S+? Because the IR filament sensor is on top of the extruder and is covered by a small plastic cover, which is held in place by one screw. See the MK3S+ E-Axis assembly instructions, Step 21 (showing the IR filament sensor on top of the extruder) and Step 38 (FS-cover assembly). In case it isn't readily apparent to you, "FS" stands for "filament sensor."
I removed the screw, removed the cover, and looked at the IR sensor to see if anything was visibly amiss. That's what I indicated above.
RE: MK3S+ has a suddenly flaky filament sensor
The believe that the Filament sensor door, mentioned the first post, is the FS-cover (E-axis assembly step 37)
My printer started doing this same thing yesterday. I have disassembled the hot end. The lever and the area around it are clean. I also used the sensor info (Main-> Service-> sensor info) menu option to verify that the filament sensor is working. The sensor is triggering as it should. My machine is MK3S+ with firmware 3.12.1-5686.
The only difference in my situation is that I had been running with filament sensor turned off. Yesterday I turned the filament sensor on. The problem started today around noon, it had been printing fine until then.
After putting it back together, I ran a test print that had failed previously. It printed w/o any problems. I started the print that was printing when the problem happened. It takes several hours to print. I will post the result here.
RE: MK3S+ has a suddenly flaky filament sensor
Yes I am quite familiar with it. Sorry to be pedantic but a door by definition has a hinge.
You removed an access panel with a screw, you would then need to remove a second screw to remove the ir break beam sensor to check the opening in it. so that’s 2 screws to check the sensor itself.
However you need to partially disassemble to access the moving lever properly. And it’s the moving lever with the magnets that activate the break beam. So yes saying you opened a door to check is misleading. The lever arm is the most problematic part of the whole mk3s and mk3s+ models.
RE: MK3S+ has a suddenly flaky filament sensor
Maybe the small M2x8 screw that fixes the IR sensor to the top of the extruder is too tight (see step 21 of E-axis assembly). During the assembly of my MK3S+ I had this issue. The IR sensor sensor didn't work until a released that screw a couple of turns from the initial setup. l don't know the reason. Possibly the sensor gets misaligned if that screw is too tightened ?.
RE: MK3S+ has a suddenly flaky filament sensor
The long print finished with no problems. I have printed several other items and all completed without the error. I have no idea why the partial disassembly and reassembly seems to have resolved the issue.
RE:
I had the same issue, MKS3+ working flawlessly for a year and then suddenly my filament sensor stops autoloading, or rather it thinks it is loaded when it isn't, which is the same issue. Turns out the solution was firmly blast the steel ball in the ball socket with an computer pressurized air can. Something small got in there and messed it up. The way I knew this was going to the LCD menu/support/sensors and seeing the filament sensor value set to a One rather than a Zero, meaning it thinks it is loaded already, thus it wont autoload. Follow the page on troubleshooting the filament sensor and just get to the part where you can slightly expose the gap where you can see the ball so your air can nozzle can go in there. You can do this while the printer is on and immediately the sensor value change to a zero, and loading then works.
RE: MK3S+ has a suddenly flaky filament sensor
asking because I'm experiencing the same issue with all of my printers, have you been able to find a solution to this?
I have a MK3S+ that has exhibited generally excellent performance for most of its three-year lifespan of casual use.
A few days ago, the printer paused mid-print with the message: "Press knob to unload filament." I've encountered this before during a filament runout, but this time, the filament was still loaded. I unloaded the filament and reloaded it, and the print resumed printing - but about 15 minutes later, it paused again with the same message.
Over the next few days, I repeatedly tried printing the same model with the same filament. My printer kept pausing at random points with the same message. Often, it would go through this process repeatedly and wouldn't actually resume. The problem has steadily grown worse - I can't even get through a full first layer on a relatively small part without encountering the message.
The only solution I've found is turning off the filament sensor. In that case, the printer runs just fine. But, of course, I'd like to have a working filament sensor, both for the functionality of detecting filament runout and for the convenience of autoloading filament.
Things I've tried without success:
* Switching filament spools, including entirely different types of filament from different manufacturers.
* Trying different models.
* Loosening the filament sensor door and inspecting the filament sensor.
* Loosening the idler screw and inspecting the idler.
* Running the entire printer calibration process.
* Updating the printer firmware. (I was using the second-to-latest firmware when the problem began.)
I suppose the part that I find most puzzling about this problem is that nothing changed at the time of the error. I was in the middle of printing a bunch of normal parts with normal filament and normal settings.
Any suggestions? Should I just replace the IR sensor? (And do IR filament sensors spontaneously fail like this?)
Thanks in advance.
RE:
I have a workaround for the sensor stuck in the "filament present" state that restores its functionality: use some pad under the sensor board.
TL;DR:
I had the filament sensor stuck at "filament present" value. After removing the top cover and the filament sensor from the assembly (step 21 in the assembling guide as mentioned above) and going to Support/sensor info menu in the printer, I figured out that the IR sensor itself is working (by repeatedly putting something into the sensor gate and watching the sensor value change between 1 and 0 immediately). So I checked the bearing ball and the lever. But without doing full print head disassembly, I found no issue there as well, and even after blasting with with cleaning air can quite a lot and pushing the bearing way deeper, so I saw the contact point of the ball and the lever (which was clear), the sensor was still set to 1 every time I attached it.
So I raised the sensor a bit by inserting small pads (a thick duct tape) at the edges of the sensor. That raised it by ~1 mm vertically, and this restored the expected functionality.
I suspect that the lever and sensor have an extremely tight tolerances and if the sensor is perhaps tightened a little bit more during the assembly, over time and many prints, something my deform just enough that the lever is permanently detected, and the pad/tape restores the original position. Or there was some tiny plastic hair I couldn't see.
The commonest cause is fragments of stringing from unloads or dust from the filament surface clogging the mechanism. In many cases a blast of compressed air as above is enough to shift it, sometimes disassembly and reassembly is required, it's common not to even see the tiny obstruction that's dislodged. There are (were?) a couple of notoriously dusty filaments that commonly caused problems and there are filament wiper/cleaner designs in Thingiverse and Printables; search four or five years back, that address this. If several printers suffer simultaneously look for the common factor - have you acquired a batch of dodgy filament? AIui spiderweb can also be a problem if filament is stored open but open storage is never wise for other reasons.
Cheerio,