E3D all metal extruder jam

Dear fellow Robo community,

I was wondering if anyone else has had this problem, where the extruder will stop dispensing plastic at an arbitrary point in the print. After I kill it, I physically cannot push the filament out of the extruder (heated to 210). I the pull it out a little bit then press it back it, then it will extrude. I've cleaned out the nozzle as best as I can, even replaced it with a new one. Can't find any edges that it may be catching on. Anyone have a solution to this?

 

Some people run their filament through foam or a sponge to catch dust that might be on it. This dust may cause the extruder to jam.

Unfortunately I'm running into jamming issues and haven't really come up with a good solution besides buying a new one.

 

Yeah, I have the same problem.
One thing i figured out is that the Z-Axis Steps/Unit was too small ( I do not understand it cause, its a metal thread and it should be the same on all printers.
(Is there a way to check if I am loosing steps? I had too increase to 2650 steps/unit)

BUT, that is not all, still get clogging by random.

AND its NOT the nozzle, its the PLA which gets thicker at the printing end and then can not pass through the extruder.

The question is: Why is the PLA getting thicker at random ?

I think its the E3D hot end which heats up to the PLA and then its cooling down again and gets stuck.
(I will play with that around a bit, e.g. turn of the stock fan not the E3D fan))

Printing: PLA 0,4 nozzle 0,15 height, 210°C, and 65°C bed (tried different PLAs, all the same)

 

Thank you very much for your input. Upon that information, I turned off the fan pointing at the head, and I know it is really high, but I set the temp to 230. So far I have had successful prints on small and medium scale.

 

Hi,

i finally figured it out:
1) Forget about Z-axis
2) The Fan OFF and minimal rejections help but DO NOT cure the problem

3) The Problem is the heat trap in combination with the diameter of the hole.
I do not know why but my bore in the upper screw has different diameters.
-> Solution I screwed everything together and then drilled a 2,1 mm hole from above to the nozzle.
Now it works, there are no edged etc in the channel, and same diameter everywhere.
Below the heat trap nothing really matters cause everything is liquid.

But next days i will post a spare part, which does not have that problem, and makes a clean mounting of the thermal sensor

Hope this helps

 

It does! In some of the other forums, they mention taking a pipe cleaner and metal polish to the tube. I guess that's something to do over beers...

 

these plans sound great, I think boring it out a little more should do it. I see the plastic thermally expanding in the shaft and the hole is just too small. if it fits perfectly snug, I see a problem with that.

 

The challenge happens here - when you're guessing about how much to bore it out....

 

Well, everyone, after conducting an experiment with print speeds and swapping back out to the robo stock print head, I am still having the issue. Possibly an Estep issue, because out of 100 mm extruded, I am coming up 8 short. there is also an excessive amount of molten plastic in the thermal isolator. I am also about to turn the head down to 180 because the isolator might be getting too hot or the filament is expanding too large for the bore. Who knows, I am not sure how to solve this at all yet.

 

E steps or take a look at wiring just to make sure you've got good connections everywhere. It's a head-scratcher for sure.

 

I would think that excessive Esteps could cause a jam not low Esteps like you seem to have. Unless your bolt is skipping and shaving the filament the 8mm low value is just probably due to the effective diameter of your bolt. I get 4 or so mm short due to the groove in my hobb. I scaled Esteps up to 753 in the firmware to compensate.

This is strange because it seems like there are a lot of us that don't have any problem with the E3D (knock on wood). I wonder if there is a quality control issue with the smoothness of the stainless tube bore.

 

Just one last thing I remembered.....when I installed, I made sure I heated up and then twisted hard on everything. I've heard of people having what they thought were tight assemblies only to get jams.

I'm not completely sure about ESteps....if it was working before, it was working before...

 

My jamings do not connect to the esteps, cause the hobbed bolt carves into the PLA cause it gets stuck -> that was how I found out where the PLA gets stuck. ATM I am designing the whole stuff as one piece with only the nozzle screwed in. Wait till Tuesday, I will post the drawings, on Thursday I will have it installed.

BTW: if you are payimg with the esteps, just adjust the feedrate on the fly or in the gcode (no firmware editing necessary)

HEATING up is a have to, thats right.

 

Hey guys, thanks for all the help and support, this has been a very interesting discussion. But, I have all the reason to believe now that it is the hobbed bolt. its shaving everything down and the clamping springs are very fatigued. Ill either find sturdier springs or unless there is another method someone has to offer.

Thanks again,
Danny

 

Hey as promised, enclosed two Versions of the hotend. Both work, but after making the first one in the workshop, we redesigned it to make manufacturing with less milling.
If someone needs this parts just write me an email dorian@milkyplay.net