Troubleshooting Ultimaker hot end because of plugging

[florianlb 0]

Hi everyone,

Sorry to start a new topic about this, but I just couldn't find the help I needed in all the things I read.

My history is the following: I've ordered an Ultimaker at the end of October and assembled it. I got my first prints shortly after, but then ran into trouble.

The symptoms I got were: the filament stops moving inside the Bowden tube and gets grated by the knurling on the hobbed bolt from the extruder drive.

My first reaction was to disassemble the extruder drive (V2) and check the tightening of the spring in the clamp. Long story short: the extruder drive was working correctly. So I figured that the problem lies with the hot end (also V2), after the filament exits the Bowden tube.

What I did about the extruder head: I cleaned it entirely at 220 °C and made sure there's no PLA inside (I'm still printing on the stock Ultimaker PLA). I then re-assembled the extruder head and moved the filament until it enters the hot end, by hand. What I realized is that the pressure seems normal while the filament has not reached the hot end and suddenly increases when the filament enters the extruder head.

I confirmed that this is indeed the problem by cleaning and inserting filament several times. My best guess is therefore: plugging occurs in my hot end. And I don't know how to solve this.

Could anyone please suggest a workaround?

Please find a picture attached that shows the sort of PLA plug I pull up whenever I try to clean the hot end.

Thanks in advance, Ultimaker Community!

Florian

[snowygrouch 1]

Print this (if you can....), add a 40mm AKASA 12V cooling fan (cost €5), add

an external 12V power supply (cost €20), run fan during printing AND keep running until hotend temp

goes below 100 Deg C after stopping printing.

Never have a plug again.

I have a V1 hotend and have never plugged it (in several months) since fitting active cooling to the hotend.

Its really important to leave the fan on after stopping printing otherwise you get heatsoak, which will

plug your nozzle.

If you cannot print one let me know and I will post you one.

If you dont want to do this I suggest you buy a V2 hotend kit, and take very special care to never ever

leave the hotend sitting at printing temperature when not printing (even 10mins will do it).

Regards

C.

[florianlb 0]

Hey snowygrouch,

Thanks for the reply.

In fact, I cannot print anything.

Tonight, I cleaned the PEEK and the brass part connecting to the nozzle and tried pushing some filament through.

It felt like it's the nozzle itself that's clogged. Does anyone know how likely that is?

I managed to push a little filament through but then the pressure needed to push further increased suddenly.

I really hope to get some input from you guys. The only option I see at the moment is to use my spare V2 hot end and replace my current nozzle with it.

[msurunner 2]

Try heating the unit up to 250 for five minutes with NO filament in it, then try to feed the filament in manually. This should allow the heat to liquefy any PLA/ABS in the hotend and "ooze" towards the nozzle. You would not want to do this with the filament still in the hot end as the heat soak will start to warm the PLA near the PFTE part which can create the dreaded plug. If you can't feed the filament through, with relative ease, after this then I would say it's semi-safe to say you have some sort of obstruction in the nozzle and to disassemble and clean it.

[IRobertI 520]

Isn't it supposed to be easy to swap nozzles on the v2 hotend? If so I'd just unscrew the nozzle and check it real quick if that's what you're suspecting. Heat it up, unscrew it and then let it cool down just a bit so that the PLA gets a little less runny. You should then be able to pull out the PLA in one chunk and it'll be easy to see if the nozzle is clear or not.

I had issues a few months ago that I eventually traced to a clogged nozzle. I don't know how it happened, maybe some contaminant in cheap PLA or something. After I cleaned it out all was well again.

[msurunner 2]

I would say it's easier to swap nozzles... Not quite "easy" yet, especially if their has been filament ran through it.

[florianlb 0]

Hi guys,

so, before swapping nozzles or changing the hot-end, I tried extruding again tonight.

After thoroughly cleaning PEEK, brass part and nozzle, I pushed some filament in.

After a few mm, I noticed that out of the peek came backflow!

I'm very surprised by this. Temperature setting was 220°C. I thought nothing the like could occur at this temperature.

I've decided to give extruding another try tomorrow. This time, at a lower temperature to check again for backflow issues. I'll report back here with the results.

I'll report back tomorrow on how this goes.

[msurunner 2]

This is a Daid post of earlier issues but it reflects my next course of action for you...

 

Care to share a photo of your hotend?

It should NOT look like this:

]https://ultimaker.googlegroups.com/atta ... w=1&part=3[/url

I've seen 2 cases of the hotend being assembled like this, and both times it causes 80% blockage in the hotend.

It should look like this]http://www.flickr.com/photos/ultimaker/%20...%20/lightbox/

With no threads showing.

It looks like you might have yours flip flopped from the photo shown.

220* can produce backflow but certainly not after only a couple mm of extrusion like that unless somethings blocking the output.

[SandervG 1,521]

It is not really clear to me if you have a hot end v1 or hot end v2?

Could you take a clear picture of your hot end?

The resistance you feel when pushing in filament manually can also be the filament reaching the end of the nozzle/hot end

and hasn't melted yet. Give it a few seconds, and try pushing it again. Does this make a difference?

If you have hot end v2, is your brass pipe installed correct, and not up side down?

Is your bowden tube reaching all the way in the teflon tube?

Thnx,

[msurunner 2]

Looks like a V2, Sander, seeing the PFTE "cold zone" part

[florianlb 0]

Hi guys,

thanks for the suggestions. First of all, please find attached a picture of my hot-end. Please correct me if it's not mounted the way it should. It's a V2.

[florianlb 0]

Some more input for you guys:

I cleaned the hot-end thoroughly and tried checking for a clog by shoving a needle through the nozzle.

Unfortunately, I couldn't see the needle tip from either side. However, judging by the way the nozzle looks both from the inside and outside, I would say it's clean and that I couldn't detect any obstacle to PLA flow.

Next step: heating up again and slowly pushing the filament in through the PEEK to check if there's still as much friction as I detected last time.

[florianlb 0]

Here's some more information. I just tried pushing the filament in by hand. I observe a plug forming in the PEEK part. When I pull it out, there's some secondary plug coming after.

After pulling out that part of filament, I pushed my screwdriver through the hot-end. It turns out that the plastic comes flowing out on the nozzle. So maybe this is okay like this after all.

I'm attaching a picture of the plugs.

Next step: putting the hot-end back together and retrying printing.

[florianlb 0]

Hi guys,

while reassembling my hot-end, I realized my ultimaker was missing its horseshoe (see attached photo).

Might this be the reason why I can't print correctly?

Thanks in advance.

Florian

[snowygrouch 1]

well just look at the photo and copy it,

That top fitting needs a clip under it too, that isnt in your picture.

So yes, without those parts correctly assembled the PTFE tube will just move up when you

print and plug the hotend.

[Daid 306]

I'm not seeing the white teflon piece in your photos? That should prevent the plug in the PEEK part.

The gap between the alu plate and your wood in the first photo is also huge.

[florianlb 0]

@snowygrouch: Indeed, I'm missing that part. However, I was able to print out a replica I made this afternoon after cleaning the nozzle. See attached picture, left. It's 1.5 mm tall. Is that enough? Could anyone provide original horseshoe measurements?

After printing out that part I though "great, this problem is solved" and went on to print out your cooler design for the hot-end. That didn't go so well: I ended up with the usual problem: the extruder driver grinding the filament and my print unfinished (see picture, right).

@daid: I took a full picture of the extruder head. Do you see anything unusual?

So I still have my last resort option: use my spare hot-end. What do you think?

Hope to hear from you guys!

[snowygrouch 1]

you cannot print this part sucessfully, it will be too weak. you should be emailing UMaker and asking for a new part.

You might be able to make one last a short time, it all depends on how far you push the machine.

[Daid 306]

What I see on that top photo looks good. (much better then what I'm seeing in the first photo) The printed clip is also good, it will hold fine.

A photo from the side front of your printer head might help in seeing if something is wrong there. Kinda like a mugshot.

The plug that shows on the 3th photo should never be able to form, as where that plug is, normally the teflon part should be. (Backflow of PLA is to be expected, and should get solid in the teflon where it can be pushed back down)

[msurunner 2]

I think that we solved one of the problems with the horseshoe clip preventing the bowden from sliding up and creating a gap in the PFTE, but I think your extrusion settings are off slightly. If I'm correct, your extruder is gradually building pressure now until it creates too much pressure for the extruder teeth to handle and it begins a grind. Try lowering your steps per e about 10 or increasing your filament diameter .1 mm. We might get a sparse part but it would show if the extrusion settings are correct.

[florianlb 0]

Hi guys,

it seems my Ultimaker is now on the way to becoming normal.

After printing the horseshoe I was discussing in my last post, my printer still grinded the filament. Somehow, I decided to print another horseshoe and fit that one on the extruder bowden end.

Magically, my filament stopped grinding and I've been able to successfully print a number of small objects. For example, I printed snowygrouch's fan duct for cooling the printer head.

However, things are not yet properly solved: my last print attempt ended because the filament started getting too thin and brittle. Could anyone have a look?

Also, my printer head is leaking.

Thanks for everything so far. I've learnt a great deal with this. Hope to solve the remaining issues too.

Florian

[msurunner 2]

Try carefully tightening the printhead while it is warm. The brass and aluminum expand at different rates through the heating process so you should check to ensure both the male brass parts (nozzle and barrel) are making proper contact in the aluminum.

Looks like you are running a Bertho upgrade, yes?

[florianlb 0]

Okay, will try this.

In fact, I'm not sure it's a Bertho upgrade. This is the standard extruder drive that came with my Ultimaker.

[snowygrouch 1]

The new one is more or less the Bertho upgrade. If it has a spring at the back its the new one.

I used the "ABS Kit" that I got with the Umaker kit, and have never had a leak problem. However

it didtnt really help that the "ABS Kit" consisted of a bag with 300mm of ABS in it, took me

quite some time online to figure out what on earth I was supposed to DO with it !

I dont know if you have used it or not yet, but the idea is that if you heat the nozzle up to about

240 (which is near to the limit of the PEEK which is about 250 depending on the variant used), you can shove

some of the ABS through (I did it by hand). The ABS will then seep into any openings in the hotend.

I pushed through about 80mm of ABS, then removed it.

The idea is that now since you will only be printing at about 220 the ABS will not melt again, and will so stay in the gaps. This should seal it up. But as mentioned above you should make sure its all tight as well. But as MSURunner said, be careful to not apply too much force, they are only little brass bits!

C.

[SandervG 1,521]

Ever since we released hot end v2 the ABS Fix Kit has been removed from the Kit because it was no longer needed.

The fact that you have a leaking hot end is most likely because it is not assembled properly.

Most likely there is a small gap between the brass pipe and the nozzle in the aluminum heater block causing the leakage.

Heat your hot end and tighten it with 2 pliers. Do it gently so it doesn't break but firm so it is tight.

Is the brass pipe far enough in the PEEK?

Is your brass pipe not installed upside down?

http://www.flickr.com/photos/ultimaker/8185563116/

If your filament is grinding, maybe your extruder drive is too tight?

If you check wiki.Ultimaker.com/Calibrate you can find a short video on how to calibrate the extruder drive upgrade.