Filament Sensor Calibration failing  

RE: Filament Sensor Calibration failing

Video would help

RE: Filament Sensor Calibration failing

New unit, so I'd get on the chat with Prusa Support, to establish a warrant claim if it's a hardware issue 

RE: Filament Sensor Calibration failing

I seem to have gotten past this after heating up the nozzle before running the test. Not sure why this worked, but it did. 

RE: Filament Sensor Calibration failing

This is a firmware issue.  3 hrs with support.  I had the same problem and did a hard reset and it went away.

RE: Filament Sensor Calibration failing

Hi Chuck is there somewhere a step for step howto how to troubleshoot the sensor ? Some Leds and so on ? thx Thomas 

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Just ran into this on the latest Firmware 5.1.3 upadate ... filament sensor check. One it pre-boot, and other is post-hardboot (turn power of/on)About to dod a factory reset and see what happens. Trying to attach videos of the process (sorry about the quality and can only attach one file at a time) but shows what happens. I'm thinging about a factory reset next :/ ... not exactly confindent the videos will show up. Ugh sorry - cant figure out why the video wont attach. .. compressed the down to below 10MB but forum is not liking it

RE: Filament Sensor Calibration failing

ok trying to uplodad second video afert a "hatd-boot" ... turning power on/off ... will do a factory reset next :/ and post video it I can.

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Looks like it you right click on the attachment and open in new tab may show the video ... will keep trying if not

RE: Filament Sensor Calibration failing

Sames issues here:

https://youtube.com/shorts/iqQnjAZjlC0

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My XL is also having the same issue (I'm on FW 5.1.2). The printer itself works fine, but because it cannot pass this calibration test, it presents a nagging message about completing calibration each time I send a print to the XL, which means that the print won't start without a manual clearing of the nag (making for more trips to the printer in my basement).  Anyone know a way to permanently dismiss this message?

This was all preceded by the filament sensors become very "flaky", i.e., not consistently detecting the filament even when it's there, which led to the issue that many others have described of stopping in the middle of the print and requesting a filament change even though there's nothing wrong.  So I disabled the sensor as many others have done. I don't know if that's part of why the current calibration/test is failing; if so, I'm in an infinite loop because for some reason you aren't allowed to re-enable the filament sensor until the calibration has been completed...which I can't do as described above.

RE: Filament Sensor Calibration failing

Dad and I had this issue with the new 5.2 firmware and we managed to get it finally.  We noticed  display on the bottom of the screen that showed the state of each filament sensor.  We used two cut pieces of filament to manually trigger each and verify on screen it was activated.  I had toggled the side filament sensor on and off about 5-6 times and saw the state changing, then manually inserted filament into the extruder, verified the sensor was triggered and then it completed calibration.  This was after a day of failures, and support offered no ideas at all.  

not sure if it was just luck, of if toggling the side sensor did something, but we got it and dad now has firmware update anxiety.  I think his XL will be on 5.2 for years after this.  

Obviously there is a firmware bug and Prusa needs to figure it out.  Support acted like this is something they e never encountered before.  

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Same thing is happening to me.  anyone have a fix? I have talked to tech support twice now and they keep wanting me to disconnect and reconnect it. 
https://www.dropbox.com/scl/fi/qujol7lqbtbmc7xih9r5p/IMG_1777.MOV?rlkey=518ikkadw44jqidvss1d5qln1&dl=0

Tech support wants to replace the part. Still thinks its a hardware issue.

RE: Filament Sensor Calibration failing

I did a hard reset and went back to 4.7.5 and it failed there too. Tech support is sending new sensor

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Same thing occurring here. Chatted with Prusa Support for quite some time, they seem to think it's a hardware issue but it completely seems to be a firmware issue. The filament sensor is working fine and is showing that it can tell when the filament is/is not inserted. But it just fails on this last step -- which indicates a bug. 

I'm not sure if Prusa is going to take this investigation further, but I hope so, as printing without a filament sensor is no fun. 

Filament sensor calibration failed

RE: Filament Sensor Calibration failing

Had the issue when i got my XL dual head in tool 2. I disassembled the tool had and found that the filament sensor board wasnt seated correctly in its place. I put the board in its designated place and the printer is running since then without any filament sensor fails.

RE: Filament Sensor Calibration failing

I had this issue after upgrading from 1 to 5 toolheads.  I reached out to Prusa support, they suggested following the cleaning instructions. That didn't help. I was ordering some other items so decided to add on another filament sensor to the order.  That one didn't pass as well.  Then I did a full factory reset (oof, had to redo the tedious multi-head calibration) and that fixed it.

So add me to the "it was firmware" group...

RE: Filament Sensor Calibration failing

Does anyone have other tricks to try? The ones mentioned in earlier messages (factory reset, cold start, heating up the nozzle before the calibration) did not work.

In my case, it is the "side sensor" that gets disabled, exactly the same as in the video posted by @bbbdesigninc.

But... if I go to Info / Sensor info / Side filament sensor, the sensor read-outs fluctuates in the range 1059..1072 when filament is inserted, and in the range 1417..1429 when there is no filament. The Tool filament sensor also fluctuates, but in a smaller range. Could the fluctuation be the cause of the calibration failure? That might explain that you occasionally pass if you try often enough.

I have a single toolhead XL, with firmware 6.0.4.

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New hypothesis: it is not due to the fluctuation of the sensor read-outs, but because the values for the "filament inserted" and "no filament" cases are too close.

In my case, when there is filament inserted, the sensor gives a value of 1065 (+/- 6), and when there is no filament, the value is 1422 (again +/- 6).

I looked through the source code of the firmware. To check whether the sensor detects filament, it compares the value of the ADC (in the sensor) to a "span", which is fixed at 310. However, in that last calibration step (where it fails), the code had multiplied that "span" criterion with 1.2 (symbol "fs_selftest_span_multiplier"). In other words, it applies a 20% safety margin.

This explains why the the calibration was successful up to that point, correctly detecting that filament was inserted in both sensors, and then failing in the next step. In normal operation (when using my values of the sensor read-outs), 1422 - 1065 = 357, which is above the criterion of 310. During that last step of the calibration, the criterion is 310 * 1.2 = 372, and the difference in the read-outs (357) is below that value.

This may therefore still be a hardware issue: the difference in the values for the "filament inserted" and "no filament" cases should be bigger. Possibly these side sensors have more tolerance than Prusa anticipated.

As an aside, I have had this machine for about a year, and it has completed calibration successfully before. Now that I re-calibrated (after moving it to a new location), it failed. Possibly, these sensors need periodic cleaning...

RE: Filament Sensor Calibration failing

I fixed my issue. The hypothesis in my last message is correct: it is caused by tolerances, noise on the readings, wear and (the main culprit in this scenario) the multiplication factor in a last step in the calibration procedure.

If sensor calibration fails after it has already detected that the filament was inserted past the two sensors:

1. Check which sensor gets disabled as a result. The remaining steps only apply to the side sensor.

2. From the main menu, select go to Info / Sensor info; then observe the values for Side filament sensor. Use a piece of filament to check on the values with filament inserted and without filament. If the difference is less than 380, that's the cause of the problem. (By the way, if the difference is less than roughly 320, you need the filament sensor replaced.)

3. Disconnect the "bowden tube" from either the back of the side sensor, or from the top of the extruder. The goal is that you can insert/remove filament in the side & tool sensors separately.

4. Still in the Info / Sensor info screen, test the side sensor with something stiffer than filament and approximately the correct width. I happened to have a piece of wire of 1.8 mm. Possibly the 2mm Allen (hex) key works well. What you are looking for is a difference between inserted/not-inserted of roughly 400.

5. Once you found something suitable, repeat the filament sensor calibration. But... for the side sensor, use the wire or tool you selected earlier. For the tool sensor, use a piece of filament. Note that this is cheating, because we calibrate with something different that the filament we will be using it with. However, the goal is only to get past the calibration, and counter to 1.2 "multiplier" factor used in that.