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Post by twicx »

Hello all,

Ok, i know I put SUPERURGENT in the title, but i've my finals for my architecture degree in 9 days, and I've a big big big model to print, in parts, and I'm about 1/10th through it. So help will earn you a beer if you're ever near me. No joke, your choice in beer.

My hot end has jammed. I tried the floss-your-printer trick with guitar wire, and it got a lot of it, but it's not feeding at all. So, I took apart the hot end, and there was a string. It was still kinda hot, and a pliers got a bit of it, but there's still a little blob. I took a photo, but it's just with my phone, but it's kinda visible.


Now, here's my questions.
1. Can i, in repetier host, heat the extruder to ~175-190 to try to just remove that?
2. If i use a drill/grinder to remove that, should that fix it?
3. What about something like nitromores?
4. If I remove this jam, will I be able to print again or is my hot end toast? <<--- This is worst case scenario, because it means I won't have a model for finals, and I'll be up the creak.

As you can probably tell, I'm panicking to f*** at the moment.

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Joined: Fri Oct 19, 2012 3:00 am

Post by oregano »

Your hot end is not toast, but your life is a little difficult here....

I'd try the following:
1. reconstruct the head, heat the hot-end up to (say) 240 - you should start to see filament dribble out the end. Try hand feeding extra filament in the from the top end and push it through.
If this works, cool it down to a more reasonable temperature, remove the filament and floss. Things should be fine (until the next jam).
2. If this does not work, pull the head apart (as it is now) - reheat the hot end up to (say) 240 (make sure you don't burn yourself - use pliers to hold the PEEK part!!!), and using a drill bit or small screwdriver see if the filament softens. If so, CAREFULLY, remove/push/drill out this bit of filament. If not, use a drill to drill it out CAREFULLY - you don't want to damage the hot end - this would have to be the last resort !
3. reconstruct the head, and try step 1 again.

If nothing else works, get a 0.3mm drill bit and drill through the tip - but this has the highest risk of damaging the hot end !

I have found the hot-end of the felix design is probably its weakest element. I spend half of my time clearing it out. I'm seriously looking at one of these J-stock/bowden approaches (posted in these forums recently) as I am becoming increasingly frustrated. (It is not helped by the fact that some of my filament has very inconsistent diameter).

I have not yet pulled the PEEK element from the hot end apart yet - as I've always been able to clear my jams with the above sort of techniques. I'm not sure how easy/possible it is - someone else will have to help you there.....

good luck !

(Later edit):
Ok, well as it turned out I ended up with another jam (I'm quite fed up with this hot end design !), so I duplicated your scenario. I think the technique mentioned after this post will work, but I went further and removed the PEEK section entirely - and left the aluminium hot end dangling - heated it up (200), and then (with the back end of a drill bit - not the sharp end) pushed the molten PLA through (holding the threaded part of the aluminium hot end with some pliers......
Last edited by oregano on Wed May 08, 2013 10:21 am, edited 1 time in total.

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Post by Makron »

I dont know if you are already doing this but , when you want to go print and heat up the hot end be sure to turn on the extruder fan at 100%.

The peek is an isolator but it can not do miracles and will get hot , and then the alu cold part get hot so the filament melts above the hot end in the peek and then you start printing it will get stuck.

What you could do now is take out the alu cold end and just heat up the hot end with the peek on it , hold the peek with some pliers and when its hot just push the filament out with a 1,9 mm drill it will come out .

Posts: 105
Joined: Fri Jan 11, 2013 1:26 pm

Post by twicx »

ok, status report.

Took apart the hot end, heated it up to 240, used a small drill to remove as much as I could. Put it back together, and changed to a fresh roll of fillament, just incase. I hand fed about 200mm through, and brown stuff came out (wtf!?). I left it at 240 and via repetier host fed through 300mm slowly, and it seemed to feed ok. Ran 3 test prints, first one was a bit dodgy, other two were good. Then did one at 220, then one at 200, seemed ok.

It's now printing part of my model, the stairs, 210 degrees, feedrate 50, flowrate 60, and seems to be going ok, although the first 2 layers were a little jittery, but nothing too bad. There's still 2hrs left on the print, but it seems to be ok for now.

So any further suggestions on how I can maintain it to print over the next 9 days till I hand up? I've about 4 models left to print, each about 100mm x 100mm x 15mm.

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