Plastic blob explosion! Help!

[bdux 1]

In the early days I just pressed print on my Ultimaker 2 extended and a few hours to days later I would have a very nice print job.

Following a more recent run of the printer apparently making up its own mind about what it was going to print (the output was neither like the Cura file nor the original design) and not getting anything that we wanted out of the printer I have spent a long time on this forum looking for answers.

I am printing in ABS. I have followed all the advice and instructions on leveling the table, cleaning the nozzle, setting the temperatures and speeds, putting glue stick on the bed... and finally the printer started (all be it very slowly) exactly what we wanted. So after 2 hours I left it. And I came back to it this morning:

You can see the base in the photo, perfectly flat and square on the buildplate

You can see what looks like an explosion of really fine wire

The thing that has me really worried because I can not work out how it could possibly have been printed is the long totally solid blob of plastic attached to the print head. This blob is also continued inside the plastic fuzz.

The fuzz also is, I just discovered, sandwiched under the buildplate.

I can't afford the time or plastic for this to happen again but my primary concern is what is going wrong and how do I fix what is clearly a really messed up print?

Thank you so much for any time and advice you can give me

Edited April 23, 2016 by Guest

[Nicolinux 288]

I have no idea what happened there other than maybe a bad batch of filament that either drew too much moisture or was otherwise damaged.

Whatever you do, do clean the long z-screw because a fine strand of ABS did attach to it and if you move the bed up now, it would get caught up in the z-nut.

[neotko 1,417]

Just wondering. Did you install a new nozzle and you only tight it by hand?

It looks like something was not well installed leaving room for the filament to escape. With a hairdryer you can heat the filament and take it out slowly to avoid damaging cables/etc.

[bdux 1]

Thank you Neotko,

I have not installed a new nozzle but I went inside the print head to have a look anyway. I heated up the nozzle using the advanced settings as I don't have a hairdryer and everything came apart easily. Although there was nothing that could have been done any tighter I did discover a burned blob that looked like it might have been extruded through a gap. Since there does not appear to be any way of loosening or tightening the nozzle I'm stuck for what I could do.

Any suggestions?

Thank you for your advice and suggestions

Kind regards

 

Just wondering. Did you install a new nozzle and you only tight it by hand?

It looks like something was not well installed leaving room for the filament to escape. With a hairdryer you can heat the filament and take it out slowly to avoid damaging cables/etc.

 

[neotko 1,417]

I see you have an original hotend with no olsson? Then the leak might come from the steelcoupler/ptfe coupler.

For the material stick to the cables you need something that can heat air to 90C that stuff there won't do any good to your machine.

Maybe the spring wasn't pushing good enough or a retract pushed up and filament started to deposit. Check the assembly guide on the troubleshooting pages and since you have all open, try to get a spring replacement.

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

I got a leak the first day assembled my um2 hotend because I didn't knew much, but with a fixed spacer and some reading you will return to perfect prints in no time.

You will need to boil the steelcoupler to remove anyresidue inside or the ptfe coupler will hit carboniced residue and won't go totally in. I say this because that happened to me after the first leak and got a second leak

[bdux 1]

Thank you Nicolinux,

I have thoroughly cleaned and re-greased the z-screw, it is running smoothly.

Whilst I was doing this I noticed that there is a lot of 'play' in the x-axis, each time the machine moves from left to right and back the whole bar connected to the motor that carries the print head pops in and out a few mm. I have tried lubricating the support bars too (with oil as instructed, not grease) but this hasn't improved things much, am I missing a washer or some sort of spacer to stop this movement? I didn't assemble this machine, it arrived pre-assembled in the box.

 

I have no idea what happened there other than maybe a bad batch of filament that either drew too much moisture or was otherwise damaged.

Whatever you do, do clean the long z-screw because a fine strand of ABS did attach to it and if you move the bed up now, it would get caught up in the z-nut.

 

[bdux 1]

Thank you Neotko for sharing your experience. I will look into everything that you mention and, when I can get the printer working again, try the spring replacement.

 

I see you have an original hotend with no olsson? Then the leak might come from the steelcoupler/ptfe coupler.

For the material stick to the cables you need something that can heat air to 90C that stuff there won't do any good to your machine.

Maybe the spring wasn't pushing good enough or a retract pushed up and filament started to deposit. Check the assembly guide on the troubleshooting pages and since you have all open, try to get a spring replacement.

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

I got a leak the first day assembled my um2 hotend because I didn't knew much, but with a fixed spacer and some reading you will return to perfect prints in no time.

You will need to boil the steelcoupler to remove anyresidue inside or the ptfe coupler will hit carboniced residue and won't go totally in. I say this because that happened to me after the first leak and got a second leak

 

[Nicolinux 288]

The play in x-direction is pretty easy to fix. Take a close look at the pulleys that are fixed on the x-rods. They should sit flush next to whatever is on their left side (a black spacer most likely). If that's not the case, loosen up the pulley and move it outwards until it is flus. Repeat this for all pulleys and take care that the toothed belt does run straight.

On my printer one spacer was too short so I printed one myself - works perfectly.

[bdux 1]

Thank you. I will print a spacer I think.

[neotko 1,417]

If you do, you could also take opportunity to:

- Check the life of your ptfe coupler

- Buy a new coupler, and since you will use the spacer you can use the new tfm couplers from ultimaker or 3dsolex TF2K that last muuuch longer than normal ptfe couplers.

[bdux 1]

Well, I did everything: cleaned it all, removed everything, readjusted everything, tightened everything, printed a quick test file and everything worked. Then I put a big print job in to print over night. This time I left a camera running on it. The footage is not quite regular enough to see exactly what happens but it looks like the start of the problems is the bed dropping in the Z direction suddenly. This is when the 'explosion' occurs as the printer starts to print in to the air.

The blob happened again but it is not clear why from the film. Disassembling the print head again has shown that the problem is worse this time and that the material seems to be coming out of the side of the nozzle and heater block. PTFE coupler does not look as bad as the ones in the Ultimaker examples but I will certainly replace that.

The voyage continues!

 

If you do, you could also take opportunity to:

- Check the life of your ptfe coupler

- Buy a new coupler, and since you will use the spacer you can use the new tfm couplers from ultimaker or 3dsolex TF2K that last muuuch longer than normal ptfe couplers.

 

[DidierKlein 729]

If you have a Z drop then have a look at this

Mainly the part about adjusting the current, this might help.

If there's a leak in the head you might need to change it, i would go for an olsson block in that case, i'm close to luxembourg if you need one you can check my shop here.

Maybe you can test by printing a big tower that prints at max height in a couple of hours, in order to check if the z-drop is happening or not. And maybe lauch a big print while you can check the printer every hour or so to make sure the plastic blob thing isn't that big