Extruder 0 reported 'tooLittleMovement'

jhelmstetterjr

I am trying to perform the calibration but shortly after the print starts the job pauses and the error message "Extruder 0 reported 'tooLittleMovement'" is displayed.

Magnetic Filament Monitor v1.7a connected to Duet Wifi E0 endstop using a crossover cable.

M591 D0
Duet3D rotating magnet filament monitor v3 on pin e0stop, enabled, sensitivity 24.80mm/rev, allow 70% to 130%, check every 3.0mm, version 3, mag 132 agc 88, measured sensitivity infmm/rev, min 0% max 0% over 11.2mm

The sensor is mounted below and against the extruder.

What steps should I take to troubleshoot this error?

Thanks

Phaedrux

Duet firmware version?

What kind of extruder is it?

Have you seen this?
https://duet3d.dozuki.com/Wiki/Duet3dFilamentMonitor_RotatingMagnetVersion#Section_Troubleshooting

jhelmstetterjr

@phaedrux The printer is a D-bot using the bowden-type extruder. Below is a picture of it. The bracket below the extruder holders the filament sensor.

Upon power up I get three green flashes. When the printer is extruding I am seeing green and red flashes on the led.

I modified the M591 parameters to give a wider tolerance range and increased the distance between comparisons but I still get the same error.

M591 D0
Duet3D rotating magnet filament monitor v3 on pin e0stop, enabled, sensitivity 24.80mm/rev, allow 10% to 190%, check every 20.0mm, version 3, mag 132 agc 88, measured sensitivity infmm/rev, min 0% max 0% over 42.3mm

M122
M122
=== Diagnostics ===
RepRapFirmware for Duet 2 WiFi/Ethernet version 3.2.2 running on Duet WiFi 1.02 or later
Board ID: 08DJM-9178L-L2MS8-6J9DA-3S86J-K8GAN
Used output buffers: 3 of 24 (22 max)
...
=== Filament sensors ===
Extruder 0: pos 0.00, errs: frame 0 parity 0 ovrun 0 pol 0 ovdue 0

alankilian

@jhelmstetterjr It seems like somehow your magnet is not turning.

But you're seeing the green/red flashing like you should when extruding, so that doesn't match.

Maybe take it apart and look carefully for something that would keep the magnet from moving.

jhelmstetterjr

@alankilian I took the housing apart and sanded the inside of the idler to allow the bearing to get closer to the hobbed gear. Put it all back together and still have the same problem. I'm going to try reprinting the housing. If that doesn't work I'll see if I can get the housing SLA printed.

Thanks for now.

dc42

@jhelmstetterjr said in Extruder 0 reported 'tooLittleMovement':

Upon power up I get three green flashes. When the printer is extruding I am seeing green and red flashes on the led.

You should see alternating green and red flashes (with gaps between them) when not extruding, and more or less continuous green flashes when it is extruding. If you don't see the continuous green flashes then the magnet is not turning. Your AGC reading is very good, so the gap between the magnet and the chip is not tool large.

jhelmstetterjr

@dc42 I reprinted the housing and reassembled but now I'm getting seven red flashes on boot up. If I'm reading the firmware correctly it means that the magnet is too far away (FLASHES_ERR_TOO_WEAK = 7)? Running the M591 D0 results in:

M591 D0
Duet3D rotating magnet filament monitor v1 on pin e0stop, enabled, sensitivity 24.80mm/rev, allow 10% to 190%, check every 10.0mm, no data received

dc42

If the magnet is too far away, first check that there are no bumps in the recess where the PCB fits, so that it fits snugly on top of the plastic in the recess. Then if necessary, sand down the flat mating surface of the top part.

jhelmstetterjr

@dc42 @alankilian @Phaedrux
Thanks for all the help. it is working now.
What I discovered:
The reason my AGC was so good was that the magnet was almost touching the hall-effect sensor. In fact, when I disassembled the MFM I found that the shaft from the hob gear was scratching a nice circle on the top of the hall-effect sensor. I believe this was causing the magnet to turn intermittently.

What I did:
I reprinted the housing using .06mm layers and gradually sanded it down until I got 90 agc. I then moved my MFM mount down about 50mm and added PTFE tubes on the enter and exit. I'm printing a XYZ calibration cube at the moment and here is my M591 D0:

Duet3D rotating magnet filament monitor v3 on pin e0stop, enabled, sensitivity 24.80mm/rev, allow 10% to 190%, check every 10.0mm, version 3, mag 131 agc 91, measured sensitivity 27.16mm/rev, min 89% max 103% over 1234.5mm

Again thanks for all the help.

dc42

@jhelmstetterjr I'm glad you fixed it. We're currently looking at sourcing stronger magnets so that the distance between the magnet and the sensor is less critical.