Extruder stops feeding

[Toby]

This has happened to me twice now. About half way through a print, the extruder stops feeding. The printer carries on quite happily printing air. I press the fillament into the extruder and it starts feeding again but of course the print is ruined.
Any insights?
Thanks.

[laneinator]

Do you have the filament guide tubes attached straight to the back of the printer? I had this problem also. The filament got caught up in the spool holder and the motor on the extruder couldn't pull it in. I printed a bracket that mounts the guide tubes further away from the printer, about the half way point of the spool, and haven't had the problem since.

[Toby]

Thanks for the input. As you say, myfilament tubes are attached directly to the back of the machine. I'lltry your suggestion and let you know the results.

[Toby]

Okay, I adjusted the feeder tubes and even applied a little WD40 to the spindle holding the filament spool. No luck, the next print quit after about an hour.

[Nargg]

Printer hotter.

[Toby]

Printer hotter.

I don't think that would help. It had been printing perfectly up to when it started to go south.
Nothing had changed, same filament, same settings on g-code.
I took apart and cleaned out the feeder gear which was full of plastic. When i put it together and tried it, same results.
It extrudes a little bit, then quits. I pushed the filament through and after some initial resistance, it started to extrude, so the nozzle isn't clogged, but when I released the pressure, it slowed down and finally stopped extruding.

[Toby]

Looks like the motor running the feed gear is not working. When I do a load filament on the left extruder, it starts extruding as soon as it has reached the correct temperature. On the right extruder, when it reaches the correct temperature, nothing.
It would seem that it has been failing for a while, hence the three occasions where it quit half way through a print. Now it doesn't work at all.
Any suggestions on how to further trouble shoot this?
Thanks,

[laneinator]

When the right extruder reaches temp, do you hear the motor TRYING to pull the filament in? If you cant tell, you should take the stepper motor off the extruder bar and run the loading sequence. You should visually verify if the stepper motor is turning the gear or not.

If it is NOT turning, I would then take the wire harness going to the right motor and put it on the left motor. Run the loading for the RIGHT extruder again, since the left is now the right as far as the printer is concerned.
If it still does not work then the problem is not the motor, it is the signal from the printer, and I would trace back the wiring to the motherboard and inspect the connections.
If it does work when the right harness is on the left motor, then the problem would appear to be the motor on the right is bad.

***** Take the left motor OFF when doing this because if it does work, it is going to try and shove filament into the cold left extruder. You will probably strip the teeth off the gear******

It wouldn't surprise me if the connections were bad somewhere, I had two wires on my printer come off the motherboard.

IF the right motor works but it doesn't pull filament in I would check the teeth on the gear, which I'm sure you have. I would also check the spacing between the gear and the wheel on the opposite side that sandwiches the filament as it comes in. If the spacing is too large then there wont be enough friction to grip the filament and pull it in.

[Toby]

Hi laneinator,
I did as you suggested and removed the right stepper motor. The gear was turning and was full of plastic residue again.
After cleaning it, I loaded it with filament from the left side just to rule out the possibility of defective (soft) material on the right, but it performed exactly the same as before.
I then forced some filament through so as to compare it with the extruded filament from the left extruder and found the right hand side was producing filament measuring .41mm whereas the left side was .56mm.
This would indicate to me that there must be some blockage in the right nozzle.
Thoughts?

[laneinator]

Its possible, but you're also trying to feed the filament at the same rate the printer is feeding it. That might be causing the difference in the filament diameter coming out.

Did you try and measure the distance between the wheel and gear? I'm wondering if its just not grabbing well enough. Not sure what it's supposed to be but you can compare it to the left side.