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Will Not Load to Nozzle  

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Ron Wensley
(@ron-wensley)
Active Member
Will Not Load to Nozzle

MK3S+ with MMU2SFirmware is 3-11-0-4955 and 1.0.6

The issue is from the LCD menu ->

Load to Nozzle
Select PLA
Preheat to 215
Load to Filament 1
MMU feeder drives and FINDA triggers (light goes out) feeder stops after about 2 seconds and does not continue to push filament to the extruder.
Makes 3 attempts, cuts filament, and tries again.
Until I get past this part there is no sense in trying to print anything.

MK3S+ prints flawlessly 
I checked IR Sensor, no issue
I checked FINDA Sensor, no issue
Factory reset on MMU2s reloaded firmware, no help with the issue.

All help is welcomed
Ron.

Posted : 01/05/2022 2:18 pm
Ron Wensley
(@ron-wensley)
Active Member
Topic starter answered:
RE: Will Not Load to Nozzle

I should have added that the filament can be push easily and freely from the MMU2 input all the way to the nozzle.

Posted : 01/05/2022 2:31 pm
GarretV liked
GarretV
(@garretv)
New Member
RE: Will Not Load to Nozzle

Same issue here. It started happening for me during a multi-color long print. Obviously I had to cancel the print. Started trouble shooting. Ran the filament calibration:

https://help.prusa3d.com/guide/service-menu-individual-filament-calibration_86376

Still no go.

Now I suspect the filament sensor in the extruder. Under the Support menu the filament sensor shows 'unknown state'. 

That's what I'll look at next.

Posted : 10/05/2022 2:23 pm
GarretV
(@garretv)
New Member
RE: Will Not Load to Nozzle

Update: My issue was indeed the sensor in the extruder. It was showing '1' for filament though none was loaded. I took it apart and, though I didn't see anything, I'm assuming there was dirt or something blocking the signal. I rechecked the status and then it was signaling properly. Ran the Load to Nozzle routine and it now works.

Posted : 10/05/2022 8:43 pm
Ron Wensley
(@ron-wensley)
Active Member
Topic starter answered:
RE: Will Not Load to Nozzle

I replaced the IR sensor and the MMU still will not load. 

Feeds for a bit then stops and retries. Finally gives up.

Posted : 15/05/2022 2:50 pm
GarretV
(@garretv)
New Member
RE: Will Not Load to Nozzle

When I checked my IR sensor reading at the menu Support / Sensor Info, after my filament wouldn't load, it read 1. I'm assuming the MMU stopped feeding because it thought it was already there. Whether my disassembly & reassembly dislodged debris or corrected a misaligned IR sensor, I'm not sure.

When your filament stops loading what is the reading on your IR sensor correct?

Posted : 15/05/2022 9:14 pm
Robin
(@robin)
Reputable Member
RE: Will Not Load to Nozzle

The IR sensor (Fil. Sensor) value has to be a stable 0 when there is no filament and a stable 1 as long as the filament is present in the extruder.

If at first you don't succeed, skydiving is not for you.

Posted : 17/05/2022 8:43 am
Ron Wensley
(@ron-wensley)
Active Member
Topic starter answered:
RE: Will Not Load to Nozzle

I may have found the problem. I attached an LED and resistor between +5 and OUT on the IR sensor.

When I select load to nozzle the extruder motor starts running continuously.
The extruder does not do this without the mmu so it is not an issue
As the extruder rotated the led would pulse on and off.

Opening the idler door to inspect I found nothing in the gears that would cause this.

I did find however that the grub screw that attaches the drive gear to the extruder motor shaft is too long.
As a result with every rotation of the extruder motor, the IR gets triggered. Resulting in a false feed.

That is the smallest grub screw I have seen and I am unsure how to get a shorter one.

Posted : 17/05/2022 1:33 pm
GarretV
(@garretv)
New Member
RE: Will Not Load to Nozzle

Could the grub screw be tightened on the round side of the shaft instead of the flat? That would make it stick out further

Posted : 17/05/2022 1:46 pm
JoanTabb
(@joantabb)
Moderator
RE: Will Not Load to Nozzle

The extruder gear grub screw should be 2mm long,

If it's 3mm, you have the wrong grub screw!
regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 17/05/2022 5:28 pm
Ron Wensley
(@ron-wensley)
Active Member
Topic starter answered:
RE: Will Not Load to Nozzle

The grub screw is 2.8mm long. I verified that it was tightened on the flat of the shaft.

I ordered a set of 2mm screws hopefully that will help.

I am going to leave the led on the IR sensor. Seems like a good modification.

Posted : 18/05/2022 12:06 am
Ron Wensley
(@ron-wensley)
Active Member
Topic starter answered:
RE: Will Not Load to Nozzle

Good thing I purchased several of these set screws.

Dam these things are tiny.

Posted : 21/05/2022 9:16 pm
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