Clogged Hot end

[3dtopo 0]

I was having a bunch of clogs between the Bowden tube and brass, but I finally got that fixed. The key was to keep the Bowden a little bit longer than the PTFE so that there was always pressure on it.

But I just got a clog, expecting it was the same as before, but there is no plastic between the brass and PTFE, it is clean.

I am extruding at 210. I recently bumped the speed up to 100 mm/s. I didn't have any issues when I was at 80 mm/s.

So I am wondering why it might have clogged. Do you think it might need to be hotter now that it is running faster? Before when I was experimenting (at say 60 mm/s) if I printed at 220 I got worse quality prints compared to 210, and I had bad warping that seems to be alleviated when printing at 210.

Any suggestions would be greatly appreciated, thanks!

[Daid 306]

You do need to up the temperature if you up the speed.

As you sure you had a clog? You could have had just a grind because of too much force needed by the extruder drive.

[3dtopo 0]

Hi Daid!

Yes, I am sure it was a clog. It did grind the filament, and could no longer feed it, but I was not able to manually push the filament in.

Well actually, the first grind I was able to force it in manually and ran enough through to be sure it was flowing again. But then a very short print later I had another grind, repeated and then another grind very shortly after. The third time I could no longer force the tube no matter how hard I tried.

That is when I decided to open it. In the brass tube there was plastic with a indentation where I was trying to force the filament. It was clearly a plug when I heated it up and pulled it out.

How much hotter should I try, 5c? 10c? Is there any rule of thumb?

[3dtopo 0]

Hmmm, well darn it, I just got another plug.

It printed flawlessly for about an hour at 216C @ 100mm/s. I haven't taken it apart yet, but I suspect it is the same issue.

I heated up the nozzle to 250C, removed the nozzle head, and I still can't force the tube through.

This is really starting to dash my hopes. Each time it clogs it is really time consuming to get it working again. It seems like the hot end has serious design issues. How am I ever supposed to ever print larger items that require many hours?

[Daid 306]

Clogging is caused by the bowden tube moving up. Which is a bit of a design flaw in the current design. A solution will be presented soon. But the most important thing is that you keep that bowden tube in place. If you are taking it apart again check you white clip, it could be damaged.

[3dtopo 0]

That design flaw is what I stated I think I fixed in my first post. I am using Owen's Bowden Clamp with a metal e-ring. But like I said, the key seems to be to make the tube a little bit longer than when screwed together so there is constant pressure on the PTFE from the Bowden.

The last clog turns out it wasn't a clog in the hot end after all (and likely the other previous clogs after fixing the hot end clogging issue). Even with the hot end removed I could not force the filament though the Bowden tube.

The next design flaw seems to be with the extruder. I am starting to suspect that it is because the filament (from Ultimaker) width must vary. If it is too thin it doesn't feed (failed print), and if it is too thick it gets mashed and can no longer pass through the Bowden cable (failed print and have to pull the fillament, cut it and re-feed it). For starters I think the Bowden cable should be slightly larger on the inside diameter (perhaps 0.5mm to 1.0mm bigger inside diameter).

Anyways, I am trying to print out a spring loaded extruder at the moment. Now if I could just print circle parts I would be set.

[Daid 306]

Saidly, the current UM is very picky on the filament thickness, and some of the filament from UM was not within specs. Right now they are doing their best to check every roll of PLA.

They also had a few bowden tubes that where not within specs and contain thin sections causing a lot of friction on the filament.

[3dtopo 0]

Do you know when the batch of bad Ultimaker filament was discovered?