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New UM2 not printing or having issues. (pictures & vid included)

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We recently received a UM2 at my work a week ago and have been playing with it. We've switched plastics (ABS and PLA) and printed a multitude of things that came out with relativly great precision.

This week we've run into some issues. At first the printer would move and not extrude. I figured out that the grooved cylinder sheathed over the stepper motor (the feed) had slipped. Initially the cylinder slipped around the axle, then later it slipped along the axle. In order to tighten this down in the right position I had to remove plastic from the feed's housing (seen below) otherwise the filament just fell behind the cylinder.

<a href="http://imgur.com/hSG7w9O"><img src="http://i.imgur.com/hSG7w9O.jpg" title="Hosted by imgur.com"/></a>

Due to the plastic sitting inside the extruder for so long at temps it formed a clog. So our prints came out unfinished and looked like this.

<a href="http://imgur.com/SQdZyJn"><img src="http://i.imgur.com/SQdZyJn.jpg" title="Hosted by imgur.com"/></a>

<a href="http://imgur.com/WKMK69F"><img src="http://i.imgur.com/WKMK69F.jpg" title="Hosted by imgur.com"/></a>

A small wire brush wire and heating the nozzel to 260C helped push out the following buggers.

<a href="http://imgur.com/UQMpC3H"><img src="http://i.imgur.com/UQMpC3H.jpg" title="Hosted by imgur.com"/></a>

The extrude still compes out at a sharp angle when extruding in free space and it causes the poly to gunk up on the nozzel (seen in the vid below). Is this because the nozzel is still clogged? It used to extrude strait down.

<embed width="440" height="420" type="application/x-shockwave-flash" src="http://v8.tinypic.com/player.swf?file=2hrzrbs&s=8"><br><font size="1"><a href="http://tinypic.com/player.php?v=2hrzrbs&s=8">Original Video</a> - More videos at <a href="http://tinypic.com">TinyPic</a></font>

NOW, after all of this i started a print and it was coming out great UNTIL this happened..

<a href="http://imgur.com/3hGKwWW"><img src="http://i.imgur.com/3hGKwWW.jpg" title="Hosted by imgur.com"/></a>

An enire layer is missing large sections and has burnt poly globs in it.

<a href="http://imgur.com/K3GEd6A"><img src="http://i.imgur.com/K3GEd6A.jpg" title="Hosted by imgur.com"/></a>

Finally to the bulk of my questions.. Is my nozzel still clogged? ive tried heating to 260C and poking in the nozzel a few times. It will extrude but still at the angle and a little black poly comes out from the heat up each time. Does this look more like an issue with my stepper or the nozzel?

Thanks for any help!


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Hi Zeig

I`d say you have both issues. The nozzle may not be fully unclogged, search this forum for "Atomic method". Also, that large chunk missing looks like the feeder skipping again. Make sure the grub screws on the feeder are nice n tight too.

As for the curling of the filament when it comes out of the nozzle, yeah this happens quite often. The trick I think is to make sure the end of the nozzle is nice n clean, when I know my nozzle is nice and hot, just before a print starts, I often wipe the nozzle with a bit of kitchen paper....careful its obviously hot.. but it keeps it nice and clean. I always watch the start of a print too, because 99% of the time you know if a print will be successful or not by observing the first few layers. If I see this curling of the filament like in your video, I grab it with my fingers and gently work it away from the nozzle before the print starts.


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The curling at the nozzle is normal just like Skint said. I just got a paper clip and bent the arm out to a right angle and use that to catch the extruded filament to guide it out of the way. You won't get burnt then. :p

As for cleaning the tip I normally just use a damp face cloth (flannel) to clean the tip just before a print and after. Has kept the tip like brand new so far.

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I just use my fingers. Haven't gotten burned yet.

curling filament touching tip is normal when it first comes out but if 50mm of hanging filament isn't enough gravity to keep it from touching tip then you need to clean the hole in the tip by sticking a needle in there and swirling it around.

Atomic method is easiest and fastest way to clean. Switching from ABS back to PLA will always need a TON of cleaning and the atomic method is best. I now do the atomic method without removing the bowden I just force the filament in through the feeder and pull it back out through the feeder. Atomic method:



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By the way heating to 260C can be counter productive and just make more gunk. 180C is plenty hot for nozzle cleaning procedures. If the atomic method isn't enough you can remove the nozzle and burn it all out and then do atomic method. Or soak in acetone for an hour.

Also visually examine your bowden tube for tiny pieces of old ABS carried along by the filamant.


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The atomic (aka cold-pull) method will Not remove all of the carbonized PLA that was created by heating it to 260C. Even if you do the cold-pull a dozen times until it comes out clean, the inside of the nozzle barrel will still be coated with high-friction black stuff. If you remove the nozzle (takes just a few minutes), soaking it in Acetone will Not remove the black stuff either, as it is not a solvent for PLA or for carbonized crud.

Some may tell you to use a blowtorch to burn off the carbon, but don't do it - you'll oxidize the brass, and the surface oxides change its dimensions slightly and leave it less than smooth.

The only non-destructive method I've found that will restore a nozzle to original condition once you overheat PLA in it or leave it sitting in the nozzle at temps over 170C without extruding, is to take a q-tip, discard 80% of the cotton so it fits snugly into the hole (while leaving a glob of cotton on the tip of it to fit the tapered bottom of the hole), and then use it to clean out the brass nozzle with metal polish until you see bare metal. I use Brasso.


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