Why it clogs? teflon coupler?

[reject 0]

Hi people,

Im having a lot of problems with my UM2, it started 1 month ago, now its impossible to make a single piece. I checked a lot of threads and used your advises but now im just lost, nothing worked.

 

The print start normally, but passed 2 o 3 min, it starts to and the filament clogs. When i pull the filament after this, there are always a ball bigger than the tube.

I did the atomic method, and the filament is always damaged, no matter the times i do ( last time i did like 10 times and the result after 4-5 was the same).

I used a 0,3mm hypoalergenic needle to clean the nozzle, but nothing changed.

I tried to eliminate the tension on the feeder using just 1m of filament, but the tension is not here.

I thing my teflon coupler is the responsible of this,

 

sorry for my english :(

Any ideas?

 

[IRobertI 520]

Is the fan at the back of the print head running? It should turn on as soon as you turn on the printer.

It also looks like your bowden tube is not pushed down all the way into the teflon piece and held in place there. When you re-assemble, make sure that you push the bowden tube all the way into the teflon, then pull the white collet up as far as it will go while pushing the bowden tube down, finally put the red horse shoe clamp back. Now try to move the bowden tube up and down, it shouldn't move.

If that doesn't work you can try to unscrew the four long bolts a couple of turns, repeat the steps above and then tighten the screws.

 

[gr5 2,167]

Try robert's suggestsions first.

Especially the 3rd fan!

I wish you showed a photo of the *other* side of the white teflon part. It's the other side that tends to go bad - the hot side. Also try pushing some virgin filament through the coupling to feel if there is friction. If so you might want to drill it out (3mm drill bit).

But I'm thinking your 3rd fan broke. The wiring breaks easily - especially under the black mesh covering just at the top of the print head.

 

[reject 0]

Thank you lRobertl & gr5.

The 3rd fan is ok, it works fine as always. Also, i always put the bowden tube with your screw method IRobertI, if i dont do this, it only prints like 20 seconds.

gr5 your idea of making a 3mm drill was my next move, the teflon part is, as you said, a bit deformed on the heated side, i cant even pull it out. Pushing some virging filament feels with a hell of friction, thats the reason i blamed the teflon.

I will try the drill next, lets see what happens. Thank you!

 

[reject 0]

2 Pictures of the bottom:

 

[IRobertI 520]

If you're feeling a lot of resistance just pushing a piece of PLA through by hand then that's definitely the issue. If it doesn't work after drilling it out I would get in contact with Ultimaker for a replacement.

 

[reject 0]

Hello again,

I had to drill a 4mm hole, the deformation inside was like 4.1-4.2mm.

Its printing right now, and im seeing a great difference, its printing almost like the old days! hope its fixed!

Thanks everyone!

 

[Daid 306]

If the deformed teflon problem comes up again. You might want to contact support, we actually have fiberglass filled teflon now, which doesn't deform as easy as the normal teflon that we used before.

 

[Dim3nsioneer 557]

Have you delivered already machines with the new teflon? If yes, when was the magical date?

 

[Daid 306]

Have you delivered already machines with the new teflon? If yes, when was the magical date?

 

No exact date. But at least a month already.

 

[DidierKlein 729]

These new Teflons are available as spare parts? I guess it will eventually happen to all of us who use the old teflon (or are they damaged because of a bad use of the printer??)

I would be interested in ordering one to prevent delay from a "broken" printer

 

[Daid 306]

These new Teflons are available as spare parts? I guess it will eventually happen to all of us who use the old teflon (or are they damaged because of a bad use of the printer??)

I would be interested in ordering one to prevent delay from a "broken" printer

 

Pretty sure support could hook you up with those parts.

Note that the price of spare parts, and getting them into the shop is something that's being worked on. (see the other topic about that)

 

[gr5 2,167]

The teflon does better if you keep the temperature lower and don't tighten the nozzle too high up (the nozzle position is adjustable so that you can make both nozzles the same height easily - if dual extrusion ever becomes available). I'm not sure which is more important, having the nozzle down low or keeping the temperature low. I think 250C is a bit hot for that part so keeping your printing at 220C might improve the teflon piece lifetime. Or maybe failure is inevitable.

 

[reject 0]

Hello guys,

My printer is definitely working as before :-P i didnt know you have improved the coupler, and i was thinking on getting this replace

http://www.aliexpress.com/item/-/1959140480.html

But obviously i prefer the fiberglass one :mrgreen:

 

[DidierKlein 729]

The teflon does better if you keep the temperature lower and don't tighten the nozzle too high up (the nozzle position is adjustable so that you can make both nozzles the same height easily - if dual extrusion ever becomes available). I'm not sure which is more important, having the nozzle down low or keeping the temperature low. I think 250C is a bit hot for that part so keeping your printing at 220C might improve the teflon piece lifetime. Or maybe failure is inevitable.

 

So printing with ABS or Colorfabb XT (temp of 250°c) will for sure damage the Teflon...

I had and odd thing last week, the filament was stuck in the teflon (i think). It had been retracted from the previous print and the next day nothing was extruded.

So i tried removing the filament and it didn't move. I removed the bowden tube and then the filament came out... should i be worried??

 

[Dim3nsioneer 557]

Maximum permanent temperature for PTFE is around 250°C, peaks are allowed up to 280°C. These are the numbers which can be found at various sources.

 

[Daid 306]

Maximum permanent temperature for PTFE is around 250°C, peaks are allowed up to 280°C. These are the numbers which can be found at various sources.

 

To bad (for us) that those maximum working temperatures do not account for deformation under stress as we found out (the bad way)

 

[Dim3nsioneer 557]

Yep. Parts under stress have lower maximum values of course. So I guess the stress comes from the spring and from the filament which is pushed by the feeder?

 

[DidierKlein 729]

So i think my Teflon is deformed too. I didn't dismantle it as i have an event saturday where i bring my UM2 with me.

It's been a couple of days i've been noticing some little underextrusion mainly when retraction is on. If i disable retraction all seems to be okay (i print at 40mm/s most of the time).

So yesterday i printed a small skull of a horse that i scanned.

0.1mm layers, 30mm/s, temp at 220°c

This was the result:

It doesn't show on the pics a lot but there are a lot of small holes in the print due to small underextrusion. So i disabled retraction and the rest of the print was okay.

After that i did the cylinder test that my UM2 passed succesfully a couple of weeks ago (even the tougher test gave me good results).

 

Attempts are from left to right.

 

It fails at 7mm3/s i know it isn't that bad but for me it's a concern because it worked perfectly before.

 

After first attempt i atomic bombed my nozzle twice. Nozzle seems clear of residue. But when i push it by hand i feel a resistance.

 

Second attempt failed quite as bad as first attempt.

 

The i removed the printed clip i have for the bowden tube because it's one of the thing i changed and put the stock clip back on.

 

Third attempt was even worse.

 

What do you guys think? Teflon or not?

 

The behaviour during retractions is a big warning for this or am i wrong?

 

[mostlyatomicbob 34]

This is really good news.

I have had 3 Teflon couplers, I have cut down all three of them to get rid of the deformation and i was looking into getting some CNC'd.

I will be keeping any eye out for there release.

Bob

 

[DidierKlein 729]

I asked support for one replacement coupler, will let you know if it's available directly or not.

 

[stu_le_brew 42]

To bad (for us) that those maximum working temperatures do not account for deformation under stress as we found out (the bad way)

I have been following this thread for some time and realise my problems are because of deformation in the teflon coupler. I have done some printing with ColorFab XT and now realise that problems started after than, I plan to disassemble the head later today. I have been in contact also with support to buy replacement parts, bowden tube ,coupler and print head.

Daid I assume that any new shipments of parts will be with the new teflon coupler ?

Stu

 

[stu_le_brew 42]

I asked support for one replacement coupler, will let you know if it's available directly or not.

I also have asked for a new coupler (plus replacement bowden tube) but as is usually the case my three months warranty has just expired !!!!

 

[DidierKlein 729]

So for your information the Teflon coupler's price is € 12,50 exl. vat and shipping.

I've also done quite a lot of prints with XT at temps of 250°c i guess it comes from there... i didn't print ABS at all.

 

[handyman 0]

Hello everybody,

Thank you for your help here. I have the same issues describe and they begun after printing with colorfab XT.

My teflon coupler is deformed at the tip, and I have ordered a new one, but I am stoped with the printing, could I cut the teflon coupler a bit, to get rid of the deformed part and use it while waiting, will it work?

Thank you