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Filament won't move through nozzle

Posted by rdear4 
Filament won't move through nozzle
May 04, 2016 09:02AM
I've done a lot of searching on this but I have only found one mention of this issue with no resolution.

My issue is that when my hotend is completely assembled and tightened down I cannot push the filament through. After some investigating I found that the hollow screw (heatbreak I think) and the heatsink don't line up. When the screw is loosened the filament will pass through.

As a temporary fix I loosened it but put a number of washers between the heater black and the heatsink. I've gotten a few low quality prints out of it but the plastic is starting to ooze out of the top of the heater block and burn. It's only a matter of time before it gets clogged or damaged.

Has anyone else encountered this issue? aNy ideas if there's anything I can do to fix it or should I scrap it and order a replacement?

Thanks in advance for any help you can provide.
Re: Filament won't move through nozzle
May 04, 2016 09:06PM
problem 1 we need to know what hot end you have
Re: Filament won't move through nozzle
May 04, 2016 11:34PM
If it's a cheap China knock-off - toss it in the garbage and buy something like a genuine E3D, genuine hexagon or genuine j-head
I've had great success with both a genuine J-head and the hexagon, but never tried an E3D.

Re: Filament won't move through nozzle
May 05, 2016 11:45AM
I bought it from Replikeo and nowhere on there site does it say what it is. But going off what I've seen and learned it looks like a generic E3D. The whole thing isn't broken it just seems that the hole through the heatsink wasn't drilled through properly.

I'm planning on purchasing a genuine E3D V6 but I wanted to see what I can do to get this working for now.

Re: Filament won't move through nozzle
May 05, 2016 12:37PM
What size filament are you using?
I don't have an E3D but I have looked at the web site.
Can you explain what you mean by the heat sink doesn't line up with the heat break. The heat sink screws on to the heat break so must line up. Do you mean the entry for the Teflon tube doesn't line up with the hole in the heat break?
I suspect the later. However if there is filament leaking from the heater block this suggests your heat break is not screwed in so it contacts the nozzle. That may be part of the problem as the heat sink will be unable to screw right down.
Re: Filament won't move through nozzle
May 05, 2016 01:30PM
I am using 3mm filament.

When everything is disassembled and you look through the heatsink the hole through it isn't straight. I'm not sure if it was bent slightly or if the hole just wasn't drilled properly or what. Either either way when the heatbreak is screwed into the heatsink the openings in both don't line up fully.

When everything is screwed in tightly I can't feed the filament through. If I unscrew the heatbreak from the heatsink about an inch the filament will then move through but its still tight. As in I can feel it scraping when I remove the nozzle and feed the filament through by hand.

If this is still confusing I can try to post some pictures when I get home.

I think what it needs is to have a 3mm hole rebored through it but I don't know anyone who can do that.

Re: Filament won't move through nozzle
May 06, 2016 07:22AM
I think you are saying that the 3mm hole in the heat sink doesn't line up with the hole through the heat break. So I assume the Teflon tube to the heat sink is OK. With the offset you have, the filament will hit the end of the heat break. By moving the heat sink away from the heat break you made space for the filament to flex and align with the heat break.
If it was mine I would start by using a drill to counter sink the heat break. This angle will help deflect the filament into the heat break. If that doesn't work you can screw the heat sink to the heat break without the Bowden then use a 3mm drill and drill from the heat break end. The heat break is steel so you wont make much damage and it will guide the drill. The heat sink is All Alloy so is soft and easily machined. You may not need to drill right through the heat sink just enough to get the filament to flex.
Do counter sink the heat break top as the filament will still rub against the edge as it enters the hole.
Just my thoughts.
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