Extruder body is clogged. What to do next?  

Re: Extruder body is clogged. What to do next?

Manuel

The extruder assembly manual can be found here: https://wiki.e3d-online.com/wiki/E3D-v6_Assembly Simply reverse the process.

You will not need a new extruder, but you may need replacement PTFE if that gets damaged during removal. You may also take the opportunity to swap the nozzle.

The blockage is most likely in the small gap between heat break and PTFE tube, so once the tube is removed applying a little heat to the heat break should get things moving.

The blockage was most likely caused by retraction value exceeding 1mm, but there are other reasons.

Peter

Re: Extruder body is clogged. What to do next?

This happened to me a LOT when trying to print Brassfill.

Take the whole extruder apart. You will see where the blockage is. For me it was usually in the metal heatbreak just where it stayed cool - this is why heating it won't clear the blockage - it is above the hot bit!

I think it is frequent retraction, combined with slow overall extrusion, which causes this. Printing Brassfill in big solid areas worked fine because the molten filament was quickly carried away from the head. In small areas, with infill, or jumping from spot to spot, the extrusion slows and the heat travels back up the (metal in my case) filament, melting it at a much higher point than usual. When that melted bit gets retracted into the cold heatbreak or PTFE tube, it goes solid and ta da! Blocked.

You can use Acetone to disolve ABS if that's what you are printing with. I think I used a drill bit in the heatbreak in the end to slowly cut out the filament, by hand. The E3D heatbreaks are not always so smooth on the interior (as Prusa seem to have found when testing the MM upgrade). Hopefully your PTFE is ok, but its easy to replace. I ordered a second heatbreak, nozzle and more PTFE from E3D here in UK - that gave me a whole spare set so I could immediately fit a clean set and keep printing while I spent time sorting out the clogged one.

You should not need to replace the heater block, nozzle or extruder body (finned). But repeatedly taking apart the hot end can easily cause damage to your thermistor and heater, so you might well want to get spares of them too while you are at it. I fitted a connector in the thermistor cable so I never had to remove it from the heater block - but the movement has broken the teeny weeny wires anyway in the end. Wish they were not so delicate...

Good luck 🙂

Re: Extruder body is clogged. What to do next?

this is why heating it won't clear the blockage - it is above the hot bit!

Usually heating does work with the extruder fan removed; after a while the heat will pass up the heat break and start to soften the blockage.

I think it is frequent retraction, combined with slow overall extrusion, which causes this.

No that's usually fine; it's only when you use retraction settings of more than 1mm (or 0.8mm) and you haven't modified the PTFE tube and/or the lower end is not perfectly square.

I think I used a drill bit in the heatbreak in the end to slowly cut out the filament, by hand.

Very bad idea. The inside of hte heat break is polished so that the filament will not stick. Inserting a hard, sharp object can easily damage the internal polish.

The E3D heatbreaks are not always so smooth on the interior (as Prusa seem to have found when testing the MM upgrade).

There was occasionally a small ridge at the point where the two drillings met, but the main reason was lack of internal chamfer and the gap between heat break and PTFE (retractions are much greater with Bowden tubes).

Hopefully your PTFE is ok, but its easy to replace. I ordered a second heatbreak, nozzle and more PTFE from E3D here in UK - that gave me a whole spare set so I could immediately fit a clean set and keep printing while I spent time sorting out the clogged one.

You will probably still need to modify the PTFE if you intend to use larger retraction.

repeatedly taking apart the hot end can easily cause damage to your thermistor and heater,

Yes, it can, but I have been changing nozzles about every 2 to 3 weeks for the past 2 years (dusty environment - because it's quicker and easier than trying to clean) and have never had any problems with cables. Probably because I am usually very careful!

Peter

Re: Extruder body is clogged. What to do next?

@Peter, I followed your advice and you were right. The clogging occurred in the heat break body. I tried heating up the heat break but could get all of the PLA out.

@mike.o, thanks for the description on how it can get clogged. I think that is what happened. I ended up using a thin drill head to remove the rest of the PLA out of the heat break. I was very careful and it worked.

Thank you both for the advice. It really helped and I learned a lot by disassembling the extruder apart. For next time, I will have spare pieces just in case something breaks.

Re: Extruder body is clogged. What to do next?

Same issue. I didn't find the official PRUSA documentation very helpful. Here you can see step by step what I did to clean up the issue. You'll need Allyn keys, needle nose pliers, needle nose tweezers, compressed air, fresh PTFE tube and some patience.

(Apologies for the image rotations. This forum doesn't seem to support CSS)

Here I've opened up the idler door. The screws are on the left side of the extruder while the idler door opens on the right
[attachment=2]20180618_215005[1].jpg[/attachment]

Here's a close up of the damaged PTFE tube and the offending filament.
[attachment=1]20180618_215452[1].jpg[/attachment]

Here you can see what needs to be replaced - the damaged PTFE tube better,
[attachment=0]20180618_220837[2].jpg[/attachment]

Did I mention that I had to remove a 45mm slug of filament?

Good luck!

Re: Extruder body is clogged. What to do next?

[attachment=0]20180618_220844[1].jpg[/attachment]