UM2 nozzle jam after 3 layers after material change (w/ pics)

[origamimavin 0]

The company I work for bought an Ultimaker 2 a little while ago, and everything has been going well. After some time, I changed over the material and started getting some problems. The 3 materials I've tried have been the stock silver PLA that it came with, some black PLA that I got from IC3D, and some red PLA from Gizmo Dorks. All are 3mm PLA, and from here on I'll be referring to them by color. I should also mention that I've been printing the silver at 50mm/s at around 230C. I found that if I printed it at 50mm/s at 220C, it had a tendency to under extrude and the extruder motor would grind. Sometimes I'd have to go as far as slow the print down to 90% to get it to print properly.

The silver has been working well, though it has jammed once or twice. I followed the procedure of heating it up and pulling the filament out to pull the clog out of the head and got it going just fine. The silver is running low, so I switched it to black. It made it a couple layers and then stopped. I switched it back to silver and it seemed to work ok, then the black didn't work again. Thinking it might be the filament, I tried the red, which clogged too. I can see that the material is flowing ok when I heat up the head and push it through by hand, and I've tried the same unclogging method as before, but I'm not getting anywhere. I tried using the silver again and now that one's clogging too.

Every time I start a print, it heats up and starts to print. I can see the extruder motor turning, and the filament is moving through. after about the 2nd or 3rd layer or so, even though the motor is still running, the filament isn't moving and nothing comes out. The extruder starts to grind a bit if I leave it for too long, as I've already adjusted the tension there, but if I remove the bowden tube from the nozzle, I can see the filament start to move again and come out. This tells me there's something wrong with the head.

When I heat it up and pull the filament out of the head, rather than seeing it come to a point, it almost looks as if it's a bit of an hourglass shape. Is something wrong inside the head where it's clogging and not coming out?

I would feel more than comfortable taking apart the head as I've built up a RepRap and have made lots of modifications to it, though the UM2 says not to take apart the head without contacting them. Since the printer was bought by the company I work for (after lots of convincing), I'd rather not mess it up and void anything.

One thing I was wondering about was when I was swapping the material and cleaning a jam, I think the head may have been pulled up into the housing that holds it a bit, since I had to do some more bed leveling afterwards. Could this have pulled part of the head apart and created a larger gap in there that it's getting hung up on?

Below are some images of everything, I'd be happy to take more pictures or video if it'd help.

[DidierKlein 729]

Hi,

In your last picture, the Steel insulator (or coupler) should touch the bottom metal part. As you said it moved when you did a cold pull (assuming you cleaned using the atomic method).

You can safely dismantle the head to put it back in place. (This will not invalidate the warranty)

For this:

(Steps are the same for dismanteling the PTFE Coupler)

Unscrew the fan shroud

Unscrew the four big screws that maintain the head in place

Unscrew the metal part that holds the rear fan (two screws on top) be careful hold it well because the spring adds pressure to it.

The put everything back in place (by hand it should do it).

Put everything back

Don't forget to re-level your bed!

Maybe you can try to put it down by putting a screw driver in one of the holes and pushing it down. Heat up before doing that (the steel coupler can break easily).

Anyway, i'm not sure if it's the reason why you have problems. One possibility i see is that the bowden tube might not be fully inserted in the Teflon, make sure it's the case.

Also, check the diameter of the black and red filaments, 3mm is too much, UM2 works with 2.85mm filaments.

If you still have problems use the atomic method until it comes out clean

Edited June 24, 2015 by Guest

[SandervG 1,521]

Was gonna say the same:

Also, check the diameter of the black and red filaments, 3mm is too much, UM2 works with 2.85mm filaments.

[danilius 118]

Sander, I have some filament that is 3.05mm on average and the UM2 handles it without a problem. This looks like the coupler is too high as Didier says. It does not really explain why the two other colours both failed and the silver did not, but I wonder if that issue is dealt with if the red and black will sort themselves out.

[cloakfiend 995]

in my experience the coupler height may not be the only issue, mine has been that high for months if not higher, now its leaning over, lol. I always wandered if it should be flush, but i've seen many pics where its not.

[origamimavin 0]

Didier, I followed your instructions and fixed the coupler to sit flush, and now it seems to be working just fine again, now with the red. I'm guessing that when I took the grey out, it lifted that up and just stopped working since. Thanks for the help! I wonder why this makes so much of a difference, does it have to do with heat distribution?

While I said it was 3mm filament, it's actually the standard 2.85mm. That was one of the first things I checked, I only wrote 3mm to differentiate it from 1.75mm which UM's don't use.

[SandervG 1,521]

Sander, I have some filament that is 3.05mm on average and the UM2 handles it without a problem. This looks like the coupler is too high as Didier says. It does not really explain why the two other colours both failed and the silver did not, but I wonder if that issue is dealt with if the red and black will sort themselves out.

 

That is very peculiar. Peculiar can happen of course, but not very common.

Do you have a stock bowden tube?

3,05 still fits if the ID is 3,16mm. If your feeder doesn't influence the diameter of your filament at all there is no problem. But since that is not always the case, 2,99 is a safe line.

Your not experiencing more friction when nearing the end of a reel?

[origamimavin 0]

Well, it was working. I printed a .5" cube just fine, but my next print stopped after the 2nd layer or so again. I just did a material change, removed the red, cut off the end section the length of the bowden tube to get rid of the grind, and put it back in. Just started another test cube, and again it stopped printing pretty quickly. Any other thoughts?

[cloakfiend 995]

You really should do atomic pulls after each material change in my opinion to save this kind of drama. but if you just load material see it coming out and then go to print and nothing comes out, it could be the coupler. Until you do the atomic pull, you wont know if there is still stuff left over in the head. Do a test, load some material wait a bit and click print. If nothing comes out, its the coupler....maybe, lol.

If its prints fine and then you try another later, and it doesnt work, then perhaps its the coupler, especially if you didnt clean out the nozzle. try overiding it. worked for me when my second prints weren't printing. worth a shot if you have nothing else to try?

Just heat up the build plate to 70, load the material into the head using move material at a high temp, and kick off the print before the head drops to 210.....

Edited June 24, 2015 by Guest

[danilius 118]

 

Sander, I have some filament that is 3.05mm on average and the UM2 handles it without a problem.

 

That is very peculiar. Peculiar can happen of course, but not very common.

Do you have a stock bowden tube?

3,05 still fits if the ID is 3,16mm. If your feeder doesn't influence the diameter of your filament at all there is no problem. But since that is not always the case, 2,99 is a safe line.

Your not experiencing more friction when nearing the end of a reel?

 

I have a stock UM2. I don't think I had any particular issues with the end of reel. I forgot to mention that I made myself a reel holder with ball bearings (gotta upload it to Youmagine at some stage) that site directly behind the feeder, so the filament does not bend through 90 degrees when entering the bowden.

[origamimavin 0]

I'm having some more issues with the printer, and I know something is wrong inside the head.

I wanted to do the atomic pull to clean the head, even though I've done it before, but wanted to take care in going through all the steps properly. I turned it on and went to move material to reverse it, and it wasn't moving. I bumped the temperature up to 260 and tried again, and it wasn't moving. I ended up pulling HARD on the back end of the filament while turning the dial, and it finally started to come out and go into the tube. I saw there was a fat blob at the end, and then saw it was stuck in the bowden. I ended up disconnecting the tube from both sides and yanking it out. The blob at the end was quite fat, as you can see below. The section of filament by the motor was all torn up, much more than usual.

I thought screw it and changed back over to the black PLA material. I connected the tubes at both ends, loaded it as usual, and immediately tried printing another .5" test cube. It printed just fine! I thought maybe the red material was just bad. I let the printer nozzle cool down to about 90C and hit print again. It printed a 2nd cube just fine. This time I let it cool off a bit more, close to standing temperature and tried printing something else. It put down all of the 1st layer and barely any of the 2nd when it clogged and stopped again. Nothing had been changed since the cubes, so I know nothing should be clogging it.

Based on the shape of the red clog, I'm thinking there may be a cavity of some sort inside the head, and when the printer cools off, it solidifies and clogs itself. Does this make any sense? Is there something I could do to fix this here, or do I need to replace some parts in the tip?

[origamimavin 0]

Well, thought about the shape of the clog and thought that maybe there was a gap in there where it was getting stuck. I just took apart the head again and pushed the teflon piece as close to the nozzle as I could. I just got it back together and have it printing another test cube now, hopefully it'll continue to work this time.

After I assembled everything and was waiting for it to heat up, I found this image online:

Which I think is exactly what was happening this time. The teflon was too thick to be easily pushed into place, so it ended up sitting higher and was leaving a gap for material to jam. I think this is a pretty poor design for the UM2, since it looks like at least one other person had a problem with this and that they don't mention anything about this in the users guide.

Hopefully it'll continue to work this time..

[DidierKlein 729]

Your Teflon still looks to high to me. The space between the steel coupler and the teflon should be around 1mm, on that last pic it looks at least 2mm.

You can change that level by heating up the nozzle, and turn the steel coupler with a screwdriver in one of the holes. If i'm not wrong turning clockwise will make the space smaller.

If this doesn't change the space then there might be some burned PLA between them?

[cloakfiend 995]

You can try to solve the problem but i gave up a long time ago, this is how i do it now (and have done for the past few months), save any headaches, all you have to do is just take the bowden out before each print, cut that crap off the end, sharpen it and follow what i do in the vid below

i.e. move the material manually back into the bowden, plug it back in, heat up the bed, heat up the nozzle, move it into the head and quickly click print before it cools down. You will never have this jammed problem again until your coupler completely fails. Its quite easy and doesn't really take much longer than doing it normally so its not really that much of a hindrance.

Edited June 26, 2015 by Guest

[origamimavin 0]

I've got the teflon back in place and it seems to be working. I did another cube yesterday that came out great and then another mostly flat piece that was so-so. I let it sit overnight and today printed a non-test part that came out great. Hopefully all is well now (knock on wood)!

Cloakfiend, I'm glad that technique works for you, but that worn't work in our case. This is a company owned printer, and even though I'm the only one using it now, I'm about to leave the company and hand it over to others who don't know how to use it as much. It needs to be as plug and play as it can be, which is why I chose the UM2 over so many other printers. Needing to baby it before and after every print would render the machine useless in this environment.

[cloakfiend 995]

Lol, fair enough but I also am in exactly the same position as you, I don't actually own my printer, but they bought it for me to print things for them and I will also hand it over when i leave, but the next guy will need to tinker with it a bit when the coupler does eventually move or fail (as it will for sure) it never hurts to know how to get around these types of problems. Also I wouldn't call doing atomic pulls strictly plug n play. I found that I had to learn how parts of the printer works for it to get the result i wanted, and theres noway i would have known without tinkering.

In my opinion 3D printers are not quite yet plug and play. I wish they were. That is were a lot of people get a wake up call. Just like print quality with no post production.

[origamimavin 0]

Also I wouldn't call doing atomic pulls strictly plug n play. I found that I had to learn how parts of the printer works for it to get the result i wanted, and theres noway i would have known without tinkering.

After building a RepRap from scratch over 4 years ago with very little calibration and troubleshooting documentation available online, and the machine taking over a year and a half to get a decent print, being able to take an UM2 out of a box and have it print a very nice octopus after 45 minutes of setup is pretty plug and play in my book. True they still need a lot of tweaking, but having a machine that works out of the box and needs some maintenance from time to time is better than starting with a box of parts. We have a couple Stratasys printers here, so some of the engineers should be able to deal with it when little problems arise, I just needed it working by the time I left.

But yes, when it comes to the everyday, non technical user, these are still far from plug and play without hassle.

[cloakfiend 995]

Dont get me wrong i love my Um2, and even with no knowledge what so ever like many people managed to get printing out of the box! Its just when things dont go the way you want or expect is what freaks some people out. but with this forum help and knowlegde at hand so as long as you dont mind a little tinkering the um is perfect for me. and as soon as i figured out acetone smoothing pla..to infinity and beyond, i recommend this printer to everyone interested in buying a 3d printer.