Knocking from Extruder (*not* clogged)

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KSheets
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Joined: Fri May 02, 2014 6:38 pm

Knocking from Extruder (*not* clogged)

Post by KSheets » Wed May 07, 2014 3:29 pm

There was a knocking sound coming from my extruder the other day, and just as I walked over to look at it, the filament (ABS) stopped coming out, so I was sure it was clogged. I removed the nozzle and let it soak in acetone for 24 hours. When I pulled it from the acetone, I could see clearly through so I know the clog was removed.

When I put the nozzle back on and hit "Extrude" to get the filament back in, the knocking persisted. It pulls the filament like it's supposed to, but it doesn't seem to be reaching the nozzle? I removed the cover to the extruder to get a better look, but everything within it is still so encased, I can't really tell what's going on.


If anyone has any suggestions -- I *really* need to get my printer working again. :(

Thank you in advance!

D3rax
Posts: 139
Joined: Thu Feb 07, 2013 7:54 pm
Location: Netherlands

Re: Knocking from Extruder (*not* clogged)

Post by D3rax » Fri May 09, 2014 7:32 am

Things you can try:

-Just to test to make sure your nozzle is not clogged: Hit extrude and push down the fillament, gently, by hand and see if it will extrude.
-Check the diameter of your fillament. Do you use OEM fillament? Third party fillament can have a bigger diameter on some places, just measure it in a few spots.
-Check your nozzle height and check if your platform is still level. When the nozzle gets to close to the prefboard the extruder will start "knocking".
-Disassemble the printhead and check if the teeth of drivegear are still clean. It's possible that chips of ABS have clogged up the gear so its not gripping the ABS (although this usually will not result in "knocking", just extruding will stop, as far as I know).
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DrewPetitclerc
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Re: Knocking from Extruder (*not* clogged)

Post by DrewPetitclerc » Fri May 09, 2014 5:34 pm

Hi All,

An area of the extruder most user forget is directly above the removable nozzle tip, the barrel can become clogged with burnt plastic and needs to occasionally be disassembled and reamed out with drill, the constriction can cause the symptom of seeming to extrude in air but any back pressure (printing) no matter how slight will stop feeding and cause strip out.
clog area.jpg
This is an area most user ignore.
clog area.jpg (115.57 KiB) Viewed 15490 times
Just like the pipes in your house can become clogged with sediment over time, so can the different plastics and temps cause a plaque build up in the hot-end tube, I usually at the first sign of issues or if I've been running an unusual filament, I will unscrew the nozzle (while hot) and the let the extruder push plastic through until I see a good solid approx. 2mm diam flow without pollutants from prior plastics/materials.

Just common sense.
Regards
Drew
Drew Petitclerc
Petitclerc Designs
Owner/Senior Principal Designer, prototype, tooling and test equipment design and 3D printing
http://flash-graphics.deviantart.com/
http://www.thingiverse.com/DrewPetitclerc

KSheets
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Joined: Fri May 02, 2014 6:38 pm

Re: Knocking from Extruder (*not* clogged)

Post by KSheets » Tue May 27, 2014 4:20 pm

We seem to have gotten the knocking sound taken care of. We used a 1/16th" drill bit to boar through the pipe, and then let everything soak in acetone just for good measure. The printer is still not working, though. When I hit "Extrude", the filament comes out as it should (basically... it's not as smooth as it used to be). But when I go to print something, first the software gives me a hard time about the nozzle height (in Maintenance, the nozzle is [and always has been] set to 118, but now, when I hit Print, it tells me that I can only enter a number for nozzle height between 125 and 145. I've never seen this message before). Wanting to just get something printing, I tried entering in a new nozzle height and finally figured out that 132 seemed to do the trick... except that there's no filament coming out. The extruder and print bed move like they're making something, but there's just nothing coming out.


Anyone know how long the warranty lasts? I'm about to throw this thing out my window. :(

dhyre
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Joined: Fri Jul 11, 2014 6:49 pm

Re: Knocking from Extruder (*not* clogged)

Post by dhyre » Sat Jul 12, 2014 5:35 pm

KSheets wrote:... used a 1/16th" drill bit to boar through the pipe, and then let everything soak in acetone just for good measure... The extruder and print bed move like they're making something, but there's just nothing coming out. :(
I've sort of inherited one like this, I think it is either an early Plus or possibly even a Basic, it has the extra filament-feed motor to help pull filament off the reel. The local K-8 school was given it, I'm trying to make it work for school in the fall. I pulled the entire hot end off, removed heater & thermistor, soaked in acetone, reamed out both ends as above, soaked again, and now filament can come out. But the extruder stepper stutters and doesn't advance, even seems to go backwards, and nothing comes out unless I push on the filament. Drive gear and that area is clear, tried adjusting positions of the mounts and such, no joy, though it really seems like the printer has forgotten how to extrude. The one calibration print I let run for a while ejected no filament, plus the X axis (extruder+hotend) didn't really move (Y & Z did), even though it will move with commands from the Maintenance dialog. I tried unplugging USB, no improvement. Somewhere I read about grounding issues, but can't get specifics of the fix - anyone familiar with this?

dhyre
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Re: Knocking from Extruder (*not* clogged)

Post by dhyre » Fri Jul 18, 2014 2:41 pm

Update:

It seems to be an overheating issue with the extruder motor. I can extrude for a little while, then it goes into this confused state. To this n00b, it seems like the stepper-motor driver needs to have its current adjusted, not sure if it's too high, or too low due to changing resistance at higher temps. ANY input welcome, including self-service info on the motherboard.

bozzo
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Re: Knocking from Extruder (*not* clogged)

Post by bozzo » Tue Aug 05, 2014 3:51 am

It seems to be an overheating issue with the extruder motor.
I am experiencing that as well (Up! Mini, but Physics works across platforms...). My nozzle was cool to the touch when the stepper motor was scorching hot after the motor had stopped running for 15 minutes or so and unplugging the whole think cooled it down in 2 minutes... It feels like it is getting actively heated when powered.

I am also fighting the same softening of the filament before it gets into the nozzle, making it OK to extrude but it stops flowing and starts knocking after 5 or 6 layers.
I am thinking about covering the motor with heatsinks and adding a fan to remove the heat.

There has to be another way, no??

D3rax
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Location: Netherlands

Re: Knocking from Extruder (*not* clogged)

Post by D3rax » Tue Aug 05, 2014 6:26 am

At the moment I'm playing with this idea: http://www.pp3dp.com/forum/viewtopic.php?f=18&t=54310.

Heatsinks and a cooling fan is not working for me. Might be that my fan does not have enough airflow but I can't get the motor cool enough.
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roller
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Re: Knocking from Extruder (*not* clogged)

Post by roller » Wed Aug 20, 2014 12:50 pm

I was also unable to get sufficient cooling on the motor side. Keep in mind that not all stepper will run at the same heat output (I can explain why but it's boring) so this stepper cooling solution will work for some but not all. Cooling the gear side is the most effective ... Drews air injection system works well but I think there are still better solutions out there ... but again some may have more heat to deal with than others.

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