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Tilt mechanism losing it's position  

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patrickmiller
(@patrickmiller)
Active Member
Tilt mechanism losing it's position

After hundreds of hours of reliable printing my SL1 has picked up an odd error. It was about 3 hours into a 5 hour print and it started making the hammering on sheet metal noise, mentioned here: https://help.prusa3d.com/en/article/loud-noises-from-printer_1797

I've followed the steps suggested to remedy this (open the case, check the sensor is clean & re-calibrate the printer) and the issue is still there. In a follow up print it took about 2 hours to bring up the error, in another an hour and a half. The parts looks great up until the error.

I think the tilt motor is losing its position over time. After i cancel the print to put a stop to the awful metal on metal banging noise it isn't able to home the tank.

I can make it home properly by moving the tank "down" until it is in range again. Moving "up" is smooth and easy until it collides with the end stop, but it isn't happy about moving down after the error, it's like i'm asking it to move past its zero position. I have to repeatedly press the fast "down" button and each time it shift by a few degrees at most. Once it is back to a reasonable tilt i can ask it to home the tank and it will do so without error.

System is 1.5.0, i've attached the logs if that's of use to anyone. log

 

Please help, i don't know how to fix this.

Posted : 30/06/2021 10:49 pm
gnat
 gnat
(@gnat)
Noble Member
RE: Tilt mechanism losing it's position

When you checked the sensor did you also check that the flag appears to be positioned correctly so that it is properly tripping the sensor? It is the same sensor they use on the MK3S/S+ for the filament sensor. As a MMU user I have significant experience in how small the IR field is and how finicky it can get if the flag isn't tripping it correctly.

It's been almost a year since I assembled mine so I forget the specifics, but maybe something with the motor, arm, or LCD is loose? 

Assuming it's not the flag, is the printer in a location where you could print with the bottom cover removed (e.g. where someone isn't going to get an eyeful of UV by accident)? If so, maybe set up a camera to record the mechanism. That might give you a better idea of what things look like when it does fail.

There is no resin or debris in the hinge of the LCD?

Maybe some good pics of all the mechanical areas involved (LCD hinge, arm, stepper, sensor) might give us some more ideas.

MMU tips and troubleshooting
Posted : 01/07/2021 2:24 pm
patrickmiller
(@patrickmiller)
Active Member
Topic starter answered:
RE: Tilt mechanism losing it's position

Thank you for the detailed and thoughtful reply. I'm pleased to say it has successfully made a thing today.

I did check that the flag is positioned in the middle of the sensor. To my eye it was exactly where it should be.

I did also check that every fastener was tight and working as intended. In a more thorough disassembly i did find a single drip of resin under the top cover, you can just make it out here.Otherwise everything looked clean.

I did as suggested and ran a print with the cover removed. In each layer it is now homing the tilt motor correctly, no growing error and no losing zero. Additionally I did a factory reset and re-calibration. Perhaps it was just software gremlins or an errant piece of dust on the sensor. If it does fail in this way again i'll try to get some video.

Posted : 02/07/2021 3:31 am
gnat
 gnat
(@gnat)
Noble Member
RE: Tilt mechanism losing it's position

Glad it's working now. Hopefully it stays that way.

MMU tips and troubleshooting
Posted : 02/07/2021 4:17 am
patrickmiller
(@patrickmiller)
Active Member
Topic starter answered:
Post 1.6 update, it's back to it's bad old ways

After updating to firmware version 1.6 this error has come back.

 

The first print after the update failed but i suspected this was due to changes in the calibration causing problems, after running a factory reset and re-calibrating the machine it worked fine for a while.

Today without any adjustments or changes since the last run of successful prints the error occurred again at 53m into a 6 hour print.

Is there any reason why this might happen after an update? Or is my SL1 just cursed and is it time to start offering incense to drive the evil spirits away?

I'll run another print today and hopefully i'll have footage of the error.

Posted : 20/08/2021 3:42 am
patrickmiller
(@patrickmiller)
Active Member
Topic starter answered:
Now with video! (hopefully)

 

https://drive.google.com/file/d/1gs4vdqKCZyeu_R8NU1nrBeNz9fcJsQ09/view?usp=sharing

Right at the end you can see the tilt mechanism is going nowhere near the end stop sensor.

Posted : 20/08/2021 7:36 am
gnat
 gnat
(@gnat)
Noble Member

Not that I think highly of them in regards to the SL1, but have you reached out to support to get their input? 

If the mechanism itself appears to be smooth and functioning, the last two options would seem to be the motor or it's driver. They don't list the motor in the spare parts area of their shop, but I wonder if it is the same as the E or X motor from a MK3 (I don't even know if those motors are the same). If you have a MK3 that can spare a motor for a test you might try swapping if they are the same and see how each printer handles the other's motor.

MMU tips and troubleshooting
Posted : 20/08/2021 2:27 pm
patrickmiller
(@patrickmiller)
Active Member
Topic starter answered:
RE: Tilt mechanism losing it's position

I have reached out to the support people and they're quite helpful. At this stage the requested photos of the parts in the tilt mechanism, so we'll see. With luck they'll suggest a software fix or send replacement components or something.

I agree that it seems like a faulty motor or driver. It works fine up to a certain point which implies it's electrical in nature. Sadly i don't have an easy way to swap out and test the motor, this is my only Prusa machine.

Posted : 21/08/2021 12:37 am
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