Extrusion issues - removing filament

[jimmyd 0]

I’m in the very first week of 3D printing and I’m loving it. However our Ultimaker has suddenly stopped extruding plastic at the preheat stage?? I have removed the extruder feeder clip (at least it swings below) at the rear of the machine and im trying to pull through the filament within the Bowden. However it will simply not budge, no matter how much pressure I apply. Ive had the machine at 210 for some time so should be more than warm enough and I just can’t get the filament out? All thoughts greatly received

J

 

[IRobertI 520]

In my experience the extruder can put on a lot more pressure/pull than your fingers. Have you tried backing the filament out using the extruder instead? Before you try it, take out the bolt and make sure it's clean so it can get a good grip on the filament. You can either turn the gear by hand or you can use the "Jog" tab of the cura printing dialog.

Using pliers might be an option as well to get you more grip on the filament but I find that more often than not you just end up breaking the filament and end up with nothing to grab onto.

Also, make sure that the head is actually hot so that there isn't some kind of malfunction with the heater.

If all that fails I'm afraid you're down to disassembly of the head. It's not as bad as it sounds. Just unscrew the four long bolts holding the nossle and heater package in place and it'll drop down (be careful not to burn yourself or the printbed obviously).

 

[jimmyd 0]

^{Thank you for your reply.}

^{Unfortunately the manual extruder won’t budge anything either?! I’m a little lost now as the plastic is to temperature (very hot to touch and the occasioanl plastic ball drips from the head) and yet I’m unable to manually extrude the filament with the wheel and I’m unable to pull through. The feed does appear to have eaten into the filament (it is roughly a third less its manufactured diameter and there is fine plastic inside?) in the housing which might explain the reason in the first place?}

 

[IRobertI 520]

Yeah, if it has already eaten away at the filament there's no chance it'll get enough grip. Then I'd say you're down to brute force with pliers or disassembly I'm afraid.

 

[jimmyd 0]

Sounds reasonable. The main issue with that is I didn’t build this machine. Could you point me in the direction of a good manual for this aspect of work? I have read that if I remove the Bowden tube (blue clip and push down?) I can remove direct from the nozzle? That would provide me with more purchase on the filament but I’m reluctant as I’m nervous of damaging the ‘business end’ of the process

 

[IRobertI 520]

You can take a look at the assembly instructions and it should hopefully become clear what you need to do:

http://wiki.ultimaker.com/Ultimaker_rev.4_assembly:_Extrusion_head

You'll want to scroll down to step 22 (doesn't hurt to read all of it though, knowing more about how your printer is assembled is great for figuring out problems) which is where the four long bolts are used to finish off the build.

When you undo those four screws the metal plate, heater block and PEEK (the brown part closest to the wood) will become free. You might need to wiggle the PEEK a bit to make it detach from the white teflon piece (the teflon piece might come off together with the PEEK, that's ok). As a precaution I'd hold on to the bowden tube as you do this just in case it's a bit stuck to prevent it from being pulled through (unlikely, but you know, just in case ).

Of course the head needs to be warm for this to work or the PLA will act as a very effective glue keeping things together.

If I was unclear, let me know.

 

[gr5 2,172]

Yes. Remove blue clip. Push down on outer ring (the blue clip was preventing this) and at the same time lift on clear plastic bowden. However you may have trouble if the filament is stuck in the bowden somewhere. Sometimes the diameter of the filament is larger than the inside diameter of the bowden.

Here are the assembly instructions - around step 21:

http://wiki.ultimaker.com/Ultimaker_rev.4_assembly:_Extrusion_head

 

[IRobertI 520]

Just to clarify why I'm talking about a more "extreme" disassembly. I'm coming from the perspective of older machines where there were sometimes issues to get the connector to grab onto the tube properly again after you removed it. Maybe that's not an issue anymore?

 

[gr5 2,172]

I don't really know. I've watched Ultimaker employees take this apart in a second on the UM2 and put it back together and the design looks identical to me. And I did it myself on the UM2 when I was helping them. But there are these little knives in there and I'm sure the teflon can get scraped and each time it gets scraped the grip can get worse. Personally I've never had to take the head apart. I had to remove the nozzle once and that's it.

So I suppose if JIMMY wants to be extra careful he can take his time and take the whole head apart the hard way. It will be a good learning experience. But if it were me I would just pull the bowden out. Much simpler. Screw the risk.

JIMMY I wouldn't go over 180C. Also leaving the head hot for more than 10 minutes (and not extruding) at a time can let the heat get up into the upper part of the head, soften the PLA and cause the exact kind of jam that you probably have.

 

[gr5 2,172]

Actually reading steps 21 through 24 again, I think it's best to loosen the 4 screws so there is a small gap between the wood and aluminum before removing the bowden. That way there isn't any pressure on the metal knives inside the bowden clamp when you go to remove it. Just like in the picture on the right in step 22.

 

[jimmyd 0]

Many thanks for the responses. Huge help.

I have now rectified the issue. i simply removed the bowden, via the clip, and resolved to brute force. It worked. The tempreture had resulted in an almost perfect 'plug' at the bowden/nozzle junction and would explain why I was having so much difficulty pulling through via the extrusion gearing mechanism at the back.

I removed the enitre filament, cut away the element that had been damaged by the gearing and reinserted the filament. Quite a few lessons learnt today. Every day is a school day.......

Many thanks once again, machine is now happily whirring away as I get back to the business of design

Great forum!

J