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molly.gibson

Extruder Plugs

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I ordered an Ultimaker last November and got it running this January. I had pretty good luck with it for the first month or so (only printed about 10 small prints in that time), until I got my first plug. I got it fixed, but I'm worried that the problem is going to persist. No matter how hard I try to put the extruder head together, I get some PLA leak out the top of the heat block (attached picture - sorry bad quality). My question is mostly preventative as it is working right now - is this a sign that another plug is on it's way? Screwing it in tighter doesn't seem to work. I'm printing at 220C right now.

How in general do you avoid this problem? I've made sure that everything is put together as tightly and securely as possible.

Thanks for any insights.

P1030760.thumb.JPG.457ff6d9058f2c4fff59d149d8501c55.JPG

 

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You could put a piece of teflon (pluming) tape between the threads. It's how the V1 hotends where usually sealed (as they where much more prone to leaking). Printing some ABS also helps. But in general screwing the hotend tight while hot works for most people. (but overtighting will break it!)

But plugs do no happen at that location, they happen up higher at the white teflon piece to the PEEK part. Make sure the white teflon fits nicely into the PEEK and makes a secure connection.

 

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When you say screwing the extruder head together, do you mean the 4 larger screws in the corner or do you mean the hot end itself, i.e. the Brass tube - Alu Block - Nozzle? The 4 screws will not help you with this leakage problem.

There is most likely a tiny gab between the brass tube and Nozzle inside the alu. block. When you it heated at 180°C, try to tighten this assembly some more. Make sure the nozzle is in all the way, and next tighten the brass tube/PEEK.

But don't use any excessive force, because the brass pipe can break.

 

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As Sander said, it's important to make the nozzle good and tight BEFORE you screw the brass tube into the aluminum block. That helps with leakage. Also, when only a tiny bit oozes out it eventually turns black and this black stuff actually serves to seal the ooze. Most people just leave the black stuff around the joint, even though it's ugly.

If you ever cancel a print in Cura, it doesn't turn off the heated nozzle (for some strange reason,) and if you let it sit for a short while, the hot end will plug. So, always avoid doing that. I often turn off the printer and unplug it for a minute after a canceled print, just so the hot end cools down. I also turn on a table fan I have sitting next to it, to blow through the printer and cool it faster.

As far as prevention goes, in my case I was having a LOT of plugs while printing, because I print at 225C and generally my prints are 5 hrs plus. That's the temperature my filament likes. On long prints at higher temps, the heat from the brass creeps upward into the nylon area and makes the incoming filament gooey and sticky. So, it eventually plugs up there at the top end of the hot end assembly. The aluminum plate, which the long bolts screw into, is a heat sink which is supposed to prevent the heat from going up that far, but it doesn't work very well if you're doing a long print at higher temperatures. What I did was design a fan shroud which directs the air between that aluminum plate and the bottom wooden plate. Even on long prints, the aluminum plate stays cool to the touch and the heat stays down at the end, where it belongs. Before doing this, I was getting plugs almost daily. After doing it, I've had 1 plug in a month and that one was because I canceled a print and forgot to shut the heat off to the nozzle. So, the fan wasn't running and the hot end was still hot. That's a guaranteed plug.

Hope this helps.

 

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As Sander said, it's important to make the nozzle good and tight BEFORE you screw the brass tube into the aluminum block.

 

Yes that is very important, but be pationt not not to break the brass. I your picture i see red fillament. That does not happen.

 

If you ever cancel a print in Cura, it doesn't turn off the heated nozzle (for some strange reason,) and if you let it sit for a short while, the hot end will plug

 

I do it it in the other way around. Before i start printing i preheat my hot end. If i wait not long enough and the first layer looks not nice i abourt the the print and way a little bit and start again.

 

On long prints at higher temps, the heat from the brass creeps upward into the nylon area and makes the incoming filament gooey and sticky.

 

i can not agree. I make very long prints (longer than 50 hours) and i have no problems with my hot end v2. At the beginning i had some problems with my fillament which causes similar problems. It looks like i have problem with a plugging nozzle, but it was the fillament which has a to big diameter. My experiance was that if the fillament has a diameter bigger than 3.05mm you will get problems when you have a long time print.

 

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