Problems with a cheap titanium heatbreak

So, I've bought this hotend:

[www.aliexpress.com]

And installed on my printer okay and configured Marlin for the new (table 13) thermistor.

At first, when I powered on the printer and turned on the heater without any material, even at 200ºC, I started to feel a "molten-almost-burnt plastic" smell, I once smelt burnt PTFE and that thing is horrible, and the "fragance" was (at least) close, but much less intensity, and no audible pops, so I thought it was because the only plastic part, the silicone sock was still new, and might be that.

So, I PID-tuned the hotend to 200ºC, never exceeding 210, and the smell persisted.

I nevertheless tried to feed PLA after heating to 200ºC, worked for a while and after a few mm's of material... bam! clogged! It was still all clean inside, but the heat-break got clogged.

I tried to clean my best the clog inside the tiny 2mm diameter hole, and eventually got to a point where 1.75mm filament could get in without any problem.

Then I tried again with another roll of PLA, same thing, heat to 200ºC, and... after a few mm's of extrusion (got to see the filament change color), it got clogged again, dissabled and is clogged again on the heatbreak.

The nozzle was barely getting plastic and is still almost clean, which suggests the plastic was getting stuck right in the heat-break, the threads were clean, which suggest it wasn't leaking.

I'm calling it quits, and buying another one.

Could they have "gotten smart" about these hotends and sprayed some lubricant to "make it work", and get away with that? Because this thing is totally useless, applying for a refund.

Edited 1 time(s). Last edit at 02/09/2019 03:06PM by RuiCarneiro.

Do you have a fan blowing on the heatsink?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
the_digital_dentist
Do you have a fan blowing on the heatsink?

Yes

Edited 1 time(s). Last edit at 02/10/2019 01:20AM by RuiCarneiro.

Make sure you have selected the right thermistor in your firmware. The printer may be reporting the wrong temperatures and heating the hotend way more than you think.

Quote
MauroPT
Make sure you have selected the right thermistor in your firmware. The printer may be reporting the wrong temperatures and heating the hotend way more than you think.

Thanks Mauro. I've compiled Marlin to the new thermistor and checked the measures temperatures with another NTC and it checks out.

Are these Ti heatbreaks well polished inside ?

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

How can I tell?

I've looked it on the side, against the light, and it seems smooth enough for me, but it has clogged before, so I'm probably not seeing metal.

Right now, it has clogged a lot, and I tried, because I can't print otherwise, but I think I found something, doing some prints and I'll post here when it has been battle tested...

Okay, I have think I found a way.

I have noticed it gets too hot, and the heater has difficulty in reaching temperatures, and cools down very fast.

So I decided to remove the side screws and try again.

So far, after 3 successful prints without clogging, seems good...

Got this.

Yeah, the clamping of the grub screws and the metal expansion weren't enough.

Trying with 1 shorter screw, that is stainless steel and not nickel plated steel.

Edited 1 time(s). Last edit at 02/14/2019 02:44PM by RuiCarneiro.