Prusa i3 Mk3/S not extruding color changing PLA beyond first layer calibration.  

Prusa i3 Mk3/S not extruding color changing PLA beyond first layer calibration.

This is an odd one. I've had the i3 MK3/S for a couple of months now. So far so good. I'm new to 3D printing so it has been a learning curve. Though I've been 3D modeling since 2004 with Autodesk 3DS Max.

Anyhow everything has been pretty straight forward so far. I have an OctoPi server running on a Raspberry Pi 3 B+ with OctoDash and a 7" Touch Screen. I've printed custom a custom Einsy enclosure that reversed the board for easy access and added a 40mm cooling fan, printed a Raspberry Pi 3 case mounted above the Einsy, a camera arm off the X-axis, a mount for the touch screen, and fan shrouds. All with an Orange to Yellow heat color changing PLA ( https://www.amazon.com/gp/product/B074T999FX/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1). I've also printed sever other versions of the Einsy case and Pi case and screen mount before setting on the final versions. I've must have put about two or three spools of that PLA through the printer. I've also used a Green to Yellow and a Purple to Pink. About 1 spool of each of those.

Now I went to print a new part the other night with the Orange to Yellow and it did the First Layer calibration fine. But when it came time to print it wouldn't extrude. I tried the Green to Yellow, same story. I've taken apart the extruder, brushed the gears, tightened the heat block to the heat break and the finned part (sorry the nomenclature escapes me at the moment, was in my head but went poof), made sure the PTFE was seated properly and the clip in place, cleaned any ooze from the block and the surrounding plastic extruder parts, cleaned the wires for the therisitor and the heating element. I removed the nozzle ensured the it was clear and in good shape (standard brass .4mm) then put it back on and tightened it down. I put the extruder back together and did another first layer calibration. All the calibrations went as expected, but when it came time to actually print with ANY of the color changing PLA's (from Prusa Slicer, both default profiles and custom profiles and from the SD straight from the LCD) NONE of the prints would extrude.  I threw in some Overture White PLA and it went to town, worked as expected. First Layer Calibration and a Tree Frog from the SD.

As I said, being new to 3D Printing this issue has me rather baffled. I know there can be issues with Glow in the Dark and Flexible materials like TPU and when you get into infused PLA's like wood, metals and carbon fiber. I plan on getting some hardened steel nozzle before I get into any exotics.

I have had success with PETG, of course I made the mistake of printing the PETG right after a PLA print, MAJOR sticking problems. Did some research and learned that those two don't play well together and it is recommended to use separate build plates and a textured for PETG would give better results. That minor change produced the results I wanted.

I've had minor success with ABS, it's a messy filament and looks like I need to treat that one with kit gloves to get good clean results. A little more research is needed on my part.

I really enjoy using the Color Changing PLA's. They come in handy when I print Pi cases, gives me a quick indicator if the SBC is running hot. And my Grandson likes the like the little color changing toys I print and my Wife thinks some of the color changing prints can be rather fun too.

So that's where I stand, rather baffled and not sure what the next step would be. Build a new hot end? I've got several more spare parts for at least one more hot and and lots of thermistors and heater cartridges. I even have a few nylon socks but I haven't had one fit quite right and it just seemed to be more of a hindrance than a help.