UM2 eating up PTFE couplers

[gr5 2,167]

If you want a really nice spacer that replaces the spring I'm partial to this one:

https://www.youmagine.com/designs/um2-spring-replacement

Regarding your ptfe part - that's the old teflon material. UM (and 3dsolex) have a newer material - it's more transluscent (you can see through it a bit more - like a frosted glass). UM may be offloading tens of thousands of the "older" style - I dont' know. But they shipped me 2 of the newer ones a few weeks ago.

[foehnsturm 969]

Just an observation from a noob, regarding this issue: Just printed some 10 hrs with a slight rattling noise until I discovered the front left long screw beeing loose. Everthing is still working perfect. So, not much tightening required I think. Distance here is 17.1

[Nicolinux 288]

@gr5: Ok, nice - I didn't know about the new 3dsolex couplers.

@Labern: I think that might be it. A long time ago I swapped the default 3rd fan (which is super loud) with this one: MC25100V2-000U-A99 (air flow: 3.0 CFM which is around 5m^3/h). I don't know how much air volume the default 3rd fan can move but I just made a test and held my hand against it. And damn the default noisy fan seems to be "stronger". So this means all this time I might have shortened the lifespan of those PTFE couplers because of the stupid fan :(

I was not able to find a better/stronger fan at this size. Where does UM get them from?

[johank 7]

I think Ultimaker is currently using Sunon MC25060V1.

When looking at that last picture the dent seems to be higher up than usual and I find the green deposits on the inside kind of strange. What kind of (PLA) filament is that?

Also, could you post a picture of the top of your heater block?

[gr5 2,167]

The original Ultimakers - in the first 4 months - had much weaker third fans. I have that on my oldest UM2 and it works fine for me. I hate the noisy fans.

I doubt it's the fan. The difference between 0 km/h wind and .1 km/h wind makes a massive difference in cooling. The difference betwen .1km/h and 3km/h is small in comparison. I found this true with electronics in experiments I did many years ago. So I prefer quiet fans.

[Nicolinux 288]

Nice, ok. I'll keep it in mind.

Alright, in the process of debugging this issue, I dusted off the side fans too (with the vacuum cleaner) and broke a wire from one fan. Re-soldered it (almost SMD style - man those things are tiny).

Since I took the head apart three times today, now there's something new. Usually when I re-assemble it and push the filament in by hand (Robert's feeder is open), I can push it all the way into the head until the filament hits the spot where the nozzle tapers off.

Now I can't push the filament past the entry point into the PTFE coupler. If I start a print the motor forces the filament through and at some point I hear a "tok" and it jumps past the PTFE entry point. This is new.

When I take out the bowden tube and push the filament in from the top (for atomic cleaning for example), then it passes the PTFE coupler without problems. The bowden looks clean and is not deformed at the end.

The only thing I remember related to this behavior is that there was some resistance when the filament passed the PTFE entry point.

I fiddled with the metal plates and thought that they are not aligned well, but that's not the case either.

Maybe this is a clue, although I don't know what causes it.

Edited March 2, 2016 by Guest

[gr5 2,167]

Here are the latest teflon isolators from 3dsolex and Ultimaker.  It's hard to tell in this photo I think - I photographed over a dark background to make it easier to see but they are more translucent than the older teflon parts because this is a newer higher temperature teflon.

Notice that 3dsolex has a groove around it - that's just a marker so we could tell the older material from the newer material when 3dsolex switched brands of teflon.

Also the 3dsolex one has a bit of a funnel inside (can't see it in the photo though).  This is to reduce the likelyhood that the filament get stuck when inserting it  - also lets you print with filament that is cracked due to the recent brittle filament issue.  I was nervous that soft pla might get stuck in that cone but it seems to not be an issue.

Edited March 2, 2016 by Guest

[Nicolinux 288]

Ok, to answer my question from before - I've changed the bowden tube and now the filament passes the PTFE coupler entry point without problems. At least one problem is gone...

[IRobertI 520]

Hey Robert, could you be so naughty and find out the size of that spacer? I am sure with my mad modeling skills, I could design and print my own

Sorry about the late reply. The spare parts list has it listed as 9.4mm.

As for the filament getting stuck at the transition between bowden and PTFE/TFM, yeah, that seems to be a somewhat recent thing. I mean, it has always been something that can happen but I've heard it a lot more often from customers lately (had a customer call about it today in fact). Not sure what has changed.

[Nicolinux 288]

Thanks Robert.

I was able to get rid of the problem by swapping the bowden tube. I think this happens because the hole is not centered in the tube. Check out the picture, the hole is a bit too far up north.

[martin-bienz 36]

I think this was also the problem on my UMO, after changing the bowden tube and relaxing / adjusting the force (bowden pushing down and the peek pushin up) to be just right, I feel I have a smoother system. Since then I did at least not have any grinded couplers anymore.

[Nicolinux 288]

Hm, now that you mention it... I have a clip that holds the bowden in place which is fairly thick. This means the bowden presses with a lot of force against the coupler. Thanks for the idea, I will print a thinner clip.