UM2+ Feeder grinding PLA vs Blocked Hot End

[alexgan 0]

Hi guys, 

 

I've had a couple of issues recently with the ultimaker 2+ that lead to replace the bowden tube. ( I didn't know how hard was to find this replacement till this week). The problem is that I still don't know what failed. I wasn't there when it happened and I'm trying to understand by looking at the scene of the crime 😀

 

I have added two pictures, one of the end where the feeder grind the PLA and another one on the hot end where It looks like the PLA leaked and built up outside the tube. I have a replacement ready to go but it was expensive to buy and to deliver to Ireland and I don't want to try until I know if the feeder is broken or the hot end needs maintenance. 

 

Can I get your opinion on what you think it could be based in your experience?

 

 

As always thanks for the support and help, really appreciated

 

Thank you,

Alex

[Torgeir 212]

Hi Alex,

 

If the filament is soft and climbing up the tube, check that the aft cooling fan is working. This fan is keeping the cold side of the hot end "cold" in order to prevent such happen.

Such thing may also happen if the printer is turned off directly after printing without cooling down.

 

Thanks

 

Torgeir

[alexgan 0]

Thanks Torgeir, I will look into it

[alexgan 0]

the cooling fan looks ok. I have replaced the tube and worked for 30s, then pla stopped coming out the nozzle. I've attached a picture of the PLA at the hot end, feeder looks good. 

 

 

[Torgeir 212]

Hi alexgan,

 

Hmm..  Seems there is something going on at the coupler. 

How is the coupler, the white insulator that's right above the heath block?

If the coupler is too much compressed in between the fixed alu spacer and the heat block, the coupler may shrink and the passage for the filament will decrease. This will create a massive resistance for the "free" feed of the filament.

 

This pressure is set by the stainless tube screw that's attached to the heat block, however if this screw is to loose, it may lead to a leakage of filament into the extruder that will ruin you day..

 

Do not ask me about how tight is enough, cause I never seen any info about this.

I just turn it down until it is only in contact with the coupler, then I add about (5-10) degrees more turn -so that I feel "some" resistance. I usually put one mark on the screw and heat sink so I can see that it is held in the right place and do not move.

 

So yes, there is a critical balance in tightening this screw..

 

These couplers is a consumable part and we should always have some in spare.

 

Hope this help

 

Torgeir

[alexgan 0]

thank you Torgeir, I do actually bought a few couplers, I will look into it and will replace if needed. Thanks for all the support 😄

[SandervG 1,518]

Also make sure that the bowden tube is firmly pressed in the coupler and that there is no gap where the filament might could expand when the temperature rises. It shouldn't require any excessive force, but something to keep in mind when you put everything back together. Otherwise there is a risk of that second photo you shared. Good luck!

[alexgan 0]

I have replaced the coupler and everything looks very good now. Thanks for the help again

[Torgeir 212]

You're welcome. 🙂

 

[alexgan 0]

I managed to get a few hours of good printing but something started to go wrong with the rear fan. It started to make noises as if it was blocked. I had to abort the print, restart the machine and heat up the nozzle to test the fan (went up to 90 Degrees) but the fan didn't start anymore. 

 

I removed the fan and cleaned it properly cause there was way too much dust on it. Connected to external voltage and worked for a few hours properly. I plugged it back into the hot end and heated it up. The fan was working again (better than before :joy:) . However, as soon as I started to print again the fan didn't start this second time.  Could this be related to me doing something wrong when replacing the coupler? 

 

I'm happy to open another thread if you think is best. 

 

 

[Torgeir 212]

Hi Alex,

 

As those wiring is mowing all the times during printing, those wires might break sometimes.

This fan is using 5 V DC, also your model is a UM2+ right. So a question, is your printer an upgraded UM2 to + version, -or is it a factory new UM2+?

I'll ask this because I'll think the factory new versions aft fan is temperature controlled, -so if this control circuit stop working it's a problem, -but can be fixed. The old UM2 have a fixed 5 V DC, so when power is applied it will start and will stay as long power is applied. Check those small connectors and carefully inspect that the wires is properly connected to the two pin connectors.

This wires may also break at the place where it "tends" to bend when printing.. It might be close to the attachment at the back of the printer or quite close to the extruder.

But this might not be because of the replacement  of the coupler, as your first pictures indicated expanded filament up hi at the "cold" side of the hot end. So if the fan have had this issue for some time, the coupler had suffered due to high temperature and become deformed due to this fact. So as you've tested the fan with external power, the issue may be just a broken (open) connection in the aft "fan wiring".

 

Hope this help.

 

Regards

Torgeir

 

 

 

 

[alexgan 0]

Hi Torgeir,

The printer is a Factory new UM2+ ( We have had it for a few years already, We have a makerspace ,so many people have come and used it along the years).

I will have a look at those connections in the back of the printer and revisit again the full fan installation to see if I missed something. If everything is ok, I guess next step is to buy a new fan. 

 

Thank you,

 

 

 

  

[geert_2 556]

If you say the fan is "making noises", it could be:

- There are filament hairs and strings stuck into it, hindering the rotation.

- Or the fan bearings are worn-out. This was very common on similar CPU-fans in older computers (286-386-etc.).

 

If you don't have a replacement yet, you can extend the life of the fan a little bit by lubricating the bearings: using a needle, cut through the silver label covering the bearing, and then inject a drop of bearing oil into it. This is obviously not a permanent solution, but I did use this quite often on computer fans in the old days, and it can extend fan life for a couple of months. Enough to keep working and meanwhile find a replacement fan (and time to install it).

 

[geert_2 556]

So I made a nice pic to illustrate this concept of lubricating the bearings of old fans. This is a 386-computer fan, not an Ultimaker fan, but the concept is the same. I have done several of these in the old days.

 

Feel with your fingernail where the edge of the bearing is. Mark this with a pen if necessary (see red circle here). Then inject a little drop near the top (thus near what would be the top after mounting it again). A little drop, not a whole syringe: you don't want it to spill oil on the glass and destroy bonding. Somewhat thicker bearing oil works best in my experience. Too thin oil leaks away, does not fill the worn-out gaps, and does not stop the shuddering of the fan.

 

Don't do this on new fans: they come lubricated optimally. Only on old worn-out ones, once they start running rough and making "rheu-rheu-rheu" sounds. And only after checking that the problem is not caused by ingested dirt, hairs, strings,..., or anything else, but really the worn-out bearing.

 

Then buy replacement fans, as this method may work for several months, but not forever. Once you find that you need to re-oil every week, then it is *really really* time to replace it.  :-)

 

For safety: use a blunt needle, or cut the sharp tip off the injection needle prior to use. You don't want to accidentally inject this stuff into your body. Cutting the needle dan be done with a Dremel tool and cutter disk (use safety glasses!).

 

Obviously, don't use this method on life-saving equipment, critical systems, aviation systems; only on sturdy systems that won't burn down when overheating a bit.

 

 

[alexgan 0]

sorry for my late reply, I took a break from the makerspace. I gave it a go to lubricating the bearings and it worked!!!. Thanks for putting time aside for preparing that picture... It really helped. 

 

My replacement fan arrived last week too, I will replace it next time the fan fails, but I probably can use the old one for a little longer. 

 

Thank you everyone again for all the support!