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leadingedge

2 weeks of printing and first hot end failure

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Having built my ultimaker over Christmas my first prints came out pretty well but after moving to my first big print I'm stuck.

After 2 hours+ of printing filament stopped feeding through - which I didn't notice for about 20 mins (when the print finished) Further attempts to print resulted in no PLA being extruded - or very little with a candy floss result. Examined, cleaned and reset the extruder. removed the PLA from the bowden tube, removed waste from the nozzle only resulted in partial prints with insufficient material flow after the first couple of layers.

So eventually resigned myself to stripping down the hot end and using a .3mm drill to clean the nozzle. Has this worked? As yet I don't know because in the process I pulled the wires off of the hot end fan (now repaired) and the main fan (when testing the hot end fan) :cry:

Reading other posts on here I can see that my problems aren't unique and the signs were there before the failure. Prints slowing down, compared to the estimated and previous print times. The cause? It looks like I mounted the hot end fan upside down - so that it was sucking air across the hot end instead of blowing. Doh!

so I'm reassured that I will get the ultimaker back up and running but best to wait until I'm in the right frame of mind.

Here's the best print I've managed so far. It's a OO scale railway carriage.

1.thumb.png.89c7d4a179870b19038a87206a31286c.png

One issue I haven't solved is very slight warping of the base. A raft has solved it on the 8 cm test piece but the 22cm full size carriage still lifted very slightly at the ends. Any suggestions?

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printing small rings around the corners and then cutting them away later.

also printing very slow and no cooling, i have actually got some good results with that and then after about the 10th layer. speed up and cooling.

or option B !

build yourself a hot bed !

welcome to the ultimaker community.

Ian :-)

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I wouldn't take a drill to the nozzle... I would first try removing the nozzle and heating it with a torch or lighter (obviously be careful handling it). The temps associated with direct flame should remove any contaminants. The more you introduce a cutting device to the nozzle, the more influence you can have on flow characteristics and can potentially generate bits of brass in the nozzle that will not melt, thus can create a plug.

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First thing you should always try on a blocked nozzle is going up to 260C, if you have flow at 260C, print an object, it might not be pretty, but it will take any 'junk' with it. I've unblocked a few nozzles this way already.

 

I've just experienced my first blocked nozzle.

Extrusion stopped half way through a print. Mercifully not a long print.

No sign of leakage. Bowden tube still in place. Tried pushing the filament by hand - nothing. Dis-assembled the hot end following the Wiki. Nothing in the PEEK.

So re-assembled the hot end and tried 240-250C for a couple of minutes as in the Wiki - nothing.

Looked on the forum and found that quoted above. So turned up to 260C. After a few minutes and quite a bit of pushing the nozzle was cleared. I kept pushing until the extrudate looked normal. Then printed a model at 210C satisfactorily.

Two suggestions:

1. That the Wiki be modified to recommend the 260C procedure.

2. That a preventative procedure be developed to AVOID blocked nozzles. Imagine a blockage after many hours of printing...

 

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After about 1 kg of PLA i had my first blocked hotend.

It seems my blockage came from a print that aborted (yes i print via USB) so i had no extrusion but lots of heat (220°) over quite some time. Apparently the heat slowly spread upward until it caused the filament to go soft enoug to form a lump above the hotend, where the heat from the hotend could no longer really reach it to make it soft enough to be pushed down.

For me, just removing the filament, cutting off the fat lump and reinserting it, then heating up and manually turning the extruder wheel to "flush" the hotend worked for me.

 

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