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What is this stuff that accumulates on the hot end?

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This looks like burnt PLA ooze squeezing out between the block. I've had that on one of my UMOs. If not taken care of eventually it will flow out over your block causing a big black mess and it'll drip onto your prints leaving splotchy black zones.

So I would recommend you heat it up to 90C. and then using pliers pull off the gunk. It should mostly come off in one piece.

Then heat it up to around 180 and then using something to hold the block tighten the threading between the block and the brass tube. You can hold the block and the peek. Be very careful though, if you torque too much you may snap the brass tube.

Again don't over tighten and definitely don't angle your torquing pressure, you just want to tighten it a bit.

Again. gentle. :p

good luck.

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I doubt it, it'll usually start flowing when you're printing due to the pressure/heat allowing more stuff to flow out. Usually turns into this black syrupy tar stuff that is quite liquidy at 210, but kinda hard candy like at room temp.

But if it's not major you can usually clean it up every 5 prints or so or whenever you do atomic pulls and you should be alright.

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That leaks because the teflon coupler tilts (if you loosen the 4 screws too much). On my experience this can also happen if the brass tube inside the peek has gone too far in, pushing the coupler up. When everything heats it expands and if the hotend isolator coupler moves the filament can leak through the peek down to the alu block.

The cleaning operation it's going to take time. But you will have to do it since this will underextrude your prints since part of the filament it's going literally where it shouldn't.

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I had this issue exaclty when i changed my coupler for the first time, its to do with the gap between the metal thing and the feeder top. I have a UM2 but im pretty sure its similer on the UMO.

The gap that you see the stuff oozing out from is too big. mine needed to be 1mm or something. yours looks massive. just heat it up get rid of the plastic and make it smaller.

file-Re8POn0Hr3.thumb.jpg.07a97cbb6e9c8de95a603d3f789978b6.jpg

Should look like this.

file-Re8POn0Hr3.thumb.jpg.07a97cbb6e9c8de95a603d3f789978b6.jpg

Edited by Guest

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The head it's really different. It doesn't relies on a spring to keep the ptfe and it has a heat break barrel surrounded by a peek to stop the heat from crawling up.

The problem it's that if you try to adjust the peek (heat barrel inside) when it's hot, it can go beyond his limits and push the hot end coupler (ptfe white part) and create a gap where the filament can leak down and inside the peek (outside the heat barrel). This can happen also if the wood that keeps the ptfe inplace it's 'not tight' and let's the ptfe a gap.

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Cheaper at my store and I guarantee the part (as does fbrc8) and I test each one at 260C.

http://gr5.org/store/

 

The fabric8 prices do seem a bit steep... Not seeing much oriented towards the UMO+ on your site, gr5... But most items I am finding easily enough via Amazon or Ebay... I was just wondering if there were some other "known" places good for getting bits in the US.

Thanks.

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The only cheaper way must be aliexpress. I got one from some chinashop and the quality it's just ok. But they sell cheap and you will need to solder the cables to the connector or buy the tools to clamp it. A pt100 with the propper connector won't be cheaper than fbr8 or gr5 shops. And on chinashops you save 2-7 bucks because you need to solder/clamp it yourself. And let's not talk about warranties...

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oh sorry - didn't notice it was UMO. Do you have UMO+? I dont' sell the thermocouple for the UMO, only the PT100 temp sensor which works for UM2 and I assume UMO+ but I don't know 100%. The one I sell is 3mm diameter (heater is 4mm diameter).

The temp sensors from ali express and other china locations are not very dependable. Many of them go open above 200C. I test mine at 260C. I think the ones at fbrc8 are all tested also - I know Simon there built a jig to test them but I don't know if he tests them all. fbrc8 is official parts seller for UM and they manufacture UM2's there. It's the only factory for UM2's outside Netherlands I believe.

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