UMO+ Globs of PLA stuck in tube

[macouno 4]

Hi all... I'm sure It's been covered before, but I could not find it using search. So please bare with me...

I just got my Ultimaker Original Plus a week or two ago and it's been printing just great... Except...

Every time I let filament cool in the machine I get nasty globs of the stuff at the print head that make it impossible to remove the filament without removing the tube... Check the image!

[LePaul 321]

I'm not sure I understand the issue?

I've only seen globs, such as in your photo, when I used the Ultimaker 2's remove filament feature.

Are the blobs on the print head?

[gr5 2,167]

I get the same globs all the time but they never cause clogs. @neotko? Ideas?

[neotko 1,417]

I get the same globs all the time but they never cause clogs.  @neotko?  Ideas?

It can be a damage over use ptfe coupler, while the UMO overpowered feeder can deal with almost anything, it has it's limits. And if the coupler is dead due normal use (it can last from 50 to 200h even when it seems that it just 'extrudes') the tip of the coupler that touches the heat barrel deforms and change shape, leaving a gap for the filament to deposit. So.. Maybe is something like that? It's quite easy on umo to take it out and take a look.

[macouno 4]

Thanks for the replies guys.

Pretty much every time I remove the filament after finishing my print (I swap filament colors a lot)... The filament has a slightly thicker 'rim' around the tip which makes it hard to pull it back through the tube.

And... most of the time a large piece of plastic is left in the extruder... so large it juts out of the top (nearly into the end of the tube)... either that or the large piece is stuck to the end of the filament making it impossible to pull the plastic out (as in the image).

[LePaul 321]

Are you using the blue horse-shoe shaped shim to lock the bowden tube into place? I don't see it in your photo

[macouno 4]

Are you using the blue horse-shoe shaped shim to lock the bowden tube into place?  I don't see it in your photo

 

Yes I do, just wasn't there in the picture.

[gr5 2,167]

If you attach the bowden correctly it shouldn't slide up and down. To do it right you have to insert it all the way while pushing down on the outer clip and then lift them up and do all this with the 4 screws loose about 1 full turn and then tighten the 4 screws 1 full turn.

anyway I'm thinking your white teflon part has died. I suggest you get one from 3dsolex (not ultimaker) because the 3d solex ones are made out of a newer kind of teflon that handles higher temperatures.

Or at a minimum you take the head apart and try to figure out where the filament is leaking into.

[macouno 4]

Ok.. so if I get this right... If there is a "glob" anywhere that is wider than the bowden tube... there must be a leak because there should not be any space for it to grow?

So either the tube is not connecting properly or the coupler is damaged.. probably

[gr5 2,167]

Exactly. Or the bowden is loose and slides up and down. Or not properly seated in the teflon. Or the brass fittings aren't all the way touching each other or not touching the teflon inside the peek part.

By measuring the filament that comes out of the head - it *might* be possible to figure out where the enlargement corresponds to. But it's difficult because the PLA likely stretched as it pulled out. So maybe measure from the tip. But then that is also tricky because you can't see how far the nozzle is drilled on the inside.

[gr5 2,167]

Also note that the failure mechanism for teflon is that it looks fine and is the right shape but it is softer under pressure. But only the portions of the teflon that got hot so the "top" and the outside might be fine but inside it might now be softer (even when cold) than it should be.

Again, get the part from 3dsolex or a partner and not Ultimaker because although Ultimaker switched to the newer, more expensive teflon for the UM2 and UM3 I don't think they switched for the UMO yet (it's possible). The 3dsolex web store is down this week but you can just email them at "sales" at 3dsolex.com. Or pick a nearby reseller that has the UMO part. I think they are about 15€ maybe.

You can tell just by looking at the teflon - older style is pure white. Newer material is more translucent. It looks darker if you put it on black paper. "Pearly"?

[macouno 4]

Update..

I've installed a new bowden tube, teflon coupler, and a fresh nozzle (3d solex 0.8mm) and all is well!