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filament Jam only on infilll?


Strange problem with filament jamming in the extruder motor.

First few layers go down great on 5th layer, the infill starts and that is where I get the filament jam in the extruder.  The failure always occurs on the first or second layer of the infill.

The printer keeps going but no filament is extruded.

The filament is jammed in the etxruder motor - it is mangled in there and flattened thus causing the jam.

The tension on the filament seems fine as it prints regular layers just fine - I also tried loosening and tightening. (inly small teeth marks on filament as it comes through).

I re-load filament and extrudes just fine - so hot end not clogged. Plus it starts all over just fine till the infill layers again.

Happens on several PLA types and temps.


Hmm.. that does sound like an odd issue. What software are you using and what values do you have set for the infill settings?

I am suffering the same situations.  I have a Creatr HS. The left stepper motor works just fine (HIPS) but recently the right stepper motor knots up my filament consistently after x amount of layers.  It has done it with MAXX PLA (black) and with Woodfill PLA.

The filament is curly where the gear makes contact with the filament.  I have removed the stepper motor and examined it ...but can't find anything wrong  Not sure I know what to look for anyway.

Very frustrating..

I have been discussing this with tech support for a while. The new firmware seems to help a bit but this still happens. It seems to be inconsistent. They have admitted that there is a heat problem and the engineers are working on a fix that may involve a cooling fans on the drive motors. I am waiting patiently. Perhaps you should ask them too and see the status. Thx


I will do that.  I'm wondering if it is heat somehow generated from the stepper motor or is it the heat rising from the build plate.  I did notice that this started happening once I raised the build plate temperature to the 60º mark.  The strange part is that this only affects the right stepper motor and filament feeder.  Left one feeds just fine...but then again, I'm shoving HIPS through the left filament feeder which has a higher melting temperature.

If it's just the surrounding heat affecting the jams, I wonder if fabricating some aluminum foil insulation as a temporary might help?

I've done some research on this issue (along with a support ticket).  I've created an illustration of what I'm encountering during a print build.  Here is a link to the image:  http://www.epromdesign.com/images/PLA-Issue.jpg

After examining the filament feeder gear I can see that it is perfectly lined up, so I know that's not the issue.  Here is what I have discovered.

(1)  It has nothing to do with the build plate temperature.  Bad diagnosis on my part.

(2)  It only happens during a dual-extruder print job where the primary feeder sits idle and waits for the other extruder to finish printing the supports.

(3)  It's not "friction" from the gear because it's not moving anywhere near fast enough to generate heat on the filament.

(4)  The resulting "melted blob" at the end of the indentation prevents the filament from exiting the filament feeder and causes the binding within the gear.

(5)  On a single-extruder print job, it continues printing without issue because the filament feeder gear doesn't sit idle long enough to melt the filament.

...My nest test is to rig up a fan for the stepper motor to see if I can cool it enough to stop the melting.

Hope this helps!

not sure if that will work, i tried a fan but could not get it to blow directly on the stepper motor, which is where I believe the problem is.

ABS seems to not have quite the difficulty but it still does have the problem.

I do think that it build up over time - which makes sense, I guess.

keep us updated - curious to see if/when they will work on this known problem.

Ken, I have a potential solution for this problem, but my last support post was screened by Leapfrog and not permitted to show.  Maybe because I added a link, I don't know?  Please email me at info@epromdesign.com and I will spec out the steps I am taking to fix this issue. 

Could you have a look at the filament once it goes through the drive unit ? 

I am mostly interested on how the filament looks. Filament jamming in the drive unit can be due to inadequate pressure on the filament ( the pinch wheel is digging into the filament and eventually jamming the drive unit) or the hot ends clog up and the amount of filament which is extruded is not constant.

Do you happen to see any filament shavings in the drive unit mainly on the pinch wheel?

Mircea.O, -- The advice I received from tech support was to "decrease" the amount of tension on the filament drive unit.  I've already done so a couple of times with the same result, but will try once more.  I think the stepper motor is getting hot enough to soften the filament should the filament remain idle for a period of time

This problem only occurs when doing a dual-extruder print with different materials.  I have PLA in the right extruder and HIPS in the left.  Only the right extruder is jamming up and it's doing so right after the HIPS has completed printing a support layer.  The PLA is just sitting there waiting for the HIPS to finish.  During this time, the PLA is melting/softening from the heat emitted from the stepper motor.  This results in a small, melted blob of PLA that is just large enough to not fit through the exit hole and thusly jamming up the gear.

Attached is a graphic that illustrates what I'm describing.

This does NOT occur during a single-extruder print as the filament is constantly being extruded and doesn't sit idle long enough to melt.

Hello again, I have been through this many times with colleagues of yours. Is us not a stepper tension problem. It was admitted to be a cooling issue that I am eagerly awaiting a fix for. Apparently your engineers are looking into a fan cooling solution. I hope it comes soon Thanks
I have made three follow-up posts to this thread (with attachments). NONE of them are making it to the thread. I'm getting extremely aggravated!
Well, since ONE post has finally made it through their screening process, I'll try another. I have a .STL file that you can print out that will fix this issue (in combination with a fan motor and adapter cable). Since every time I post this info it never shows in the thread I ask that you email me: INFO at epromdesign dot com.. I have to write it out this way because of the screening process.

Dear KEN petschauer,

Please understand it is not only a cooling issue. You can cool the drive unit motors as much as you want if the pressure on the filament is not ok and the hot ends are partially clogged and filament is not getting through cooling the filament is pointless to cool the drive units.

And I have been printing on the HS printer without fans cooling the drive units and the printer finishes the 3D model without a issue. Our engineers have developed a cooling system which is now being tested and once it is confirmed that it is working properly it will be available for customers.

Thank you.

Glad to hear you are working on a fix.

Looking forward to it.

I realize how complex this is and how everything has to be working just right.

Appreciate the help.

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