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The Cause of a Bowden Pop, will v2 extruder help


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Posted · The Cause of a Bowden Pop, will v2 extruder help

So I got my ultimaker back in June and had been using it on and off, with multiple problems all along. The most common one that has plagued a lot of us is the Bowden Tube popping.

Fastforward to 2 days ago, I accidentally managed to melt my peek as the temp sensor was not connected to the aluminum block and the heater was on. (NOT GOOD)

Worked the entire last night to print without a peek and use fricton to hold the hot end in place. It worked and no popping of the tube etc, none of the problems because I could tighten the Brass Tube and see how much force it needed.

But a few things I have realised while working on a no-peek machine (milled PTFE tube with the brass tube a few mm inside the PTFE tube, surely more than the existing peek architecture). A lot of PLA leaked from the sides of the brass tube Cube.thumb.JPG.aa8489a63f2052727acc74599fec0d8f.JPG

(Orange = PLA, White = ABS)

But this didnt seem to affect my prints at all. Infact the ultimaker was printing perfectly. Which makes me believe that PLA expands considerably and the expanded PLA leaks out from the sides. (Extruder Calibration needed maybe, dont know how with the latest CURA)

Now if I had a functional PEEK, this leak would get arrested, but the PLA would still expand would it not?

Again you could say that I could be over heating the PLA causing expansion, but I've used two different Spools, purchased both from Ultimaker and the temperature for a stable print have been 185 (Brown PLA) and 235 (Orange PLA).

I could be completely wrong in understanding the problem and the importance of the peek in the design. Could someone help me to figure out how the V2 will help with expanding PLAs.

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    Posted · The Cause of a Bowden Pop, will v2 extruder help

    Ummm, well firstly if you leave out major components of the hotend you should expect a huge failure.

    Which is what has happened. The PTFE tube just about works when put into the top of the PEEK barrell

    because its just about at the top of the hot-zone. The PEEK screws into the brass hotend so its a much

    more leak-free setup that what you have done there.

    You have just used a "push fit" to seal the liquid PLA right in the middle of the hotzone. Honestly

    Im really shocked that even worked at all.

    PLA has very very minimal thermal expansion, your problem is that your current setup cannot possibly

    seal anything.

    As for your previous problems with the hotend (of course I am a bit biased here), but what you need

    is active cooling. Its the only way to be 100% reliable, it seems that the V2 is much better than the V1, but

    doesnt seem to be a 100% cure. Probably a bit marginal so that any less than perfect assembly or operation

    can still give issues (like leaving the hotend at full temp without the printer extruding for long periods for example).

    So I think you need the assemble it again with ALL the parts in place !

    Then I think you should buy an 8 euro 40mm fan, and print a hotend cooling duct (I can email you the STL). This will completely cure it of any plugging, full or partial. However you will probably need a 2nd power supply to

    run the 12 V fan properly, because its also essential to leave it running for 10mins after stopping printing

    (prevents heat-soak).

    Good luck.

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    Posted · The Cause of a Bowden Pop, will v2 extruder help

    I understand, and was always meant to be a proof of concept. What was astonishing was that, it printed fine, got a few hours of printing from it (had to keep cleaning the molten PLA though) inspite of the leakage, and the PLA that I have (purchased from Ultimaker) expands a fair bit, simillar to ABS.

    Ive ordered the V2 hot end, waiting for it come.

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