heat separator clogging despair
April 05, 2013 10:33AM
Hi all,

I've built a Prusa with Megatronics, it has a 0.35mm printhead, uses 1,75mm filament trough a classic hinged extruder, only tried PLA for now.

I have had some perfect prints, especially small prints come out great. So I now my calibration must be ok.. I guess.

Bigger prints, though, are a pain, because after let's say an hour into a print, the heat separator is sure to clog up. The filament seems to melt into it, and the next thing to fail is the hobbed bolt, grinding the filament away.

I'm convinced that it is a temperature issue, but I can't solve it on my own!

I've tried some things.

I tried cooling the heat separator by mounting an ex-netbook fan next to it, blowing directly at it. seems to make no difference.

I've tried several new heat separators, because I thought I had damaged one as I tried to clean it with a small drill.

I've tried playing with the temperature. 185° doesn't cut it. The hobbed bolt will dig into the filament, the prints will be inconsistent and weak (I guess the placement and the type/brand of temp sensor can play a role). I tried raising the temperature by 1 degree at a time, while looking for consistent infill (any inconsistency will show clearly there) . At around 200° - 202°, the prints are perfect. But then it clogs up after a while.

I've tried lowering printing speeds; perimeters at 20 mm/s, infill 30,...

I thought the filament retraction I had set might deform the filament, so got rid of that...

I am finally desperate and looking for new ideas. I tried to find similar posts on this form, but they are scarse, it doesn't seem like everyone has this problem, it must be something I'm doing wrong.

The only ideas I have left: try to build a liquid cooled heat separator smiling smiley, or, getting rid of the 0,35 mm printhead, and switch to 0,5mm and 3mm filament.

But I first want to see if someone here could help me out with some more ideas..

thanks!

Turok
Re: heat separator clogging despair
April 11, 2013 04:48PM
so.. no easy solution I guess??

I ordered a 0,5mm , we'll see..
Re: heat separator clogging despair
April 12, 2013 01:03AM
I wonder sometimes if PLA doesn't "cook" in the hot-end leading to blockages. When I have a problem like that, I remove the filament and use a "pusher" to force the hot melt out of the nozzle. I normally like to start the heating up first, then feed in the filament immediately prior to starting a print. Leaving the heater on in standby is not a good idea either.
mcp
Re: heat separator clogging despair
April 12, 2013 07:42AM
Hi,
I had a simular issue with ABS and it went away after exchanging my RRW V5 against a reprap-fab V3 with active Cool-End cooling. Which HotEnd are you using ? J-Heads seems also to have this issue where on some it can be cured by cooling. (Fan on Peek) You could give the new E3D a try, or a Longsword Excalibur type. I guess all use the same idea of using stainless steel with active cooling, This works for me at least like a dream. No clogging, no jaming, just printing constantly...
Also it looks like this melting upwards is different for every material, and as long as nobody knows exactly what Filament he gets we won't be able to find a general solution. Some filament works well, but if you order the same next week, the game starts again.
The stainless steel without PTFE at least seems to help a bit.
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