RTV getting on print, causing failures

[bdorney]

When I'm printing something the hot end will cause the RTV or something else to heat and turn into a gooey black substance. This substance gets in my prints which then interferes with the nozzle which causes failures. Has anyone else had this problem or know a way to fix it?

[Eaglezsoar]

What RTV did you use, the manufacturer info?

[cassetti]

Pics?

Where is the gooey black substance coming from?

[jesse]

or something else to heat and turn into a gooey black substance

It may be melting PEEK, does it smell like burnt rootbeer? What temperature did you use?

[bdorney]

The name of the RTV is Permatex Ultra Copper sensor-safe High Temp RTV Silicone Gasket Maker.

It seems to coming from the gaps between the nozzle and the outer rim of the hotend.

[bdorney]

Im printing around 235C

[Eaglezsoar]

PLA or ABS? I would assume ABS at those temperatures.

[bdorney]

Nylon 618 actually

[jesse]

The name of the RTV is Permatex Ultra Copper sensor-safe High Temp RTV Silicone Gasket Maker.

I used almost the same material and didn't have that problem.

http://www.harborfreight.com/3-oz-rtv-s ... 90026.html

Make sure the liquid isn't coming from the gray plastic (PEEK) on the hot end.

[img]http://i.imgur.com/QZ1dmUh.jpg[/img]

[foshon]

Umm.... You have major calibration issues. The part being printed should never contact the base of the nozzle. Which is IMHO how the permatex got on there.

Looking at your print (what was it supposed to be?) I see extrusion calibration issues and layer shift issues, at least. I would read through the calibration portion of the manual again, verify that make the specified changed to the eeprom.

[badgerman]

I had a similar thing on my H1. I attributed it to oils and continually re-heated materials from the filament or something leeching out of the Peek. Obviously I am not 100% on that 'science' but I can say with moderate certainty that it isn't from the RTV as it leeched from areas not covered by the RTV on mine.

On mine, it came from the threads at either end of the Aluminium heating element (nozzle and peek sides) and I resolved it by using PTFE tape to seal the threads. I haven't seen the problem since, and I haven't seen any contaminated material coming from the nozzle and I use white filament - so it would be seen.

It does look like you have some bigger issues with calibration though buddy.

If you dismantle the hot end, to put PTFE tape on the threads, stick the metal parts in the oven and cook them a bit until the black goo is molten - this will allow you to clean it off. It might take a couple of goes though as it cools rapidly and solidifies. Probably be worse as you are using the N618.

[Polygonhell]

Looks to me like the PEEK melting rather than RTV.
Have you verified your temperature with a thermocouple?
If the thermistor is loose it can read massively low, 230 obviously ought to be fine, but you need to verify the thermistor is reading accurately.

[bdorney]

So it looks like I need to take my hot end apart to check the PEEK. As far as calibration goes, is the layer shift issue something I should address with z-height/endstop tuning or is it a software settings problem? And is there any reason these problems don't show up until half way through the print? And the object was supposed to be Mario