SKR 1.4 Turbo Filament Runout Issue

Everything seems good to go except this one last issue. Everytime I try to print, it immediately returns a filament runout error.

I started with filament runout disabled. I just happen to have a couple of filament runout sensors that I know work, so I decided to connect one and enable it to see if that would correct the problem.

Unfortunately it did not despite the filament runout sensor appearing to work perfectly.

M119 shows it triggered when appropriate and open when not. The runout sensor light is on when the filament is loaded.

But a print won’t start without the filament runout error poping up. When I click ok and press resume, it pops up again.

Any help would be gratefully appreciated.

Just as an addendum, I can disable the filament runout sensor in the tft3.5, which probably would have resolved the print issue in absence of a runout sensor, but either way, the runout sensor being present with or without filament doesn’t fix the problem when it is enabled.

Three quick suggestions.

  1. If you can, try leaving the sensor connected but don’t run the filament through it, run it right into the extruder. If the print runs it means the filament sensor logic got flipped and can be fixed in firmware.
  2. Disable the sensor from the TFT and see how it goes.
  3. Go back and revisit any recent changes to hardware and configuration settings to make sure they didn’t have an unintended consequence.

My recent sensor problem was very hardware specific (Prusa R4 extruder with the optical sensor). The permanent fix is to open up the extruder and do a little trimming to remove interference between a part of the case and the sensor flag. The quick fix was backing the top 2 stepper motor screws out about 1/4 of a turn. I “broke” it by fixing something else.

The runout sensor had been working fine since it was installed months ago, but I decided to adjust the X belt tension, which required partial diassembly of the X axis and extruder assemblies. I never touched the sensor during this process. Apparently I tightened those screws a little more than they had been before. I spent days looking for a gcode cause since I “knew” there wasn’t anything physically wrong with the extruder or sensor but it kept making me do filament changes over and over.

There’s a reason for the machine’s behavior. It can be figured out.

Thank you gentlemen for your continued assistance and support. I will generally try anything because I know there is always so much to learn about any subject.

I feel way further ahead tonight than I have in the past week. While it needs tuning, I did manage a basic test print tonight, so I am glad I pushed through rather than reverted back.

The filament sensor error is an odd one in it’s behavior. I’m pretty sure I have correctly set it up in firmware as I have done it before for another of my printers. I found it interesting that the TFT3.5 default setting was to have the filament sensor on regardless of the firmware on the SKR 1.4. It tripped the sensor every print even when disabled in the SKR 1.4 Firmware.

I will try enabling it on the tft 3.5 tomorrow to troubleshoot it further. I know it is triggered when the filament is present and open when it is not.

Thank you again for all your help.