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The extruder cooling fan on my Orion stopped working. I tried fixing the cables, but it still will not work... but the extruder is Peek with a teflon tube. Why a fan???!! I removed the cowling and taped the fan out of the way and the Orion is printing PLA just fine.

You really need a fan if you are printing PLA. It will eventually jam if you don't. You can live dangerously if you want, you might get lucky or you might end up with a PIA jam.

This is what can happen if you don't have a peek fan running on your HotEnd.

That's not true. That's what happens when you over-temp (247C+) the hot end. The PEEK fan is there to keep the cold section cool so you don't have PLA jams.

g.

With PLA you have basically 3 distinct states inside the hotend, the liquid plastic at the hot bit, the solid plastic where it's fed in and with PLA specifically a section of rubbery material that will grip the sides of the hotend and cause a jam. As you print heat can creep up the barrel and cause that rubbery section to get longer increasing the amount of it that can grip the side and eventually you get enough of it that even the PTFE liner will be gripped, and you will jam.
What appears to be the case is that the heat creep is largely a function of convection rather than conduction, the fan just keeps colder air around the PEEK preventing the creep. In fact for most designs you need a very minimal amount of airflow to stop a jam, often even the head moving can be sufficient.

Personally having spent a lot of time cleaning out hotends a few years ago before I new about fans, it's not a lot of fun, so I run a fan, when I first got the Rostock, I printed PLA with an 80mm fan blowing across the bed, then later added a 25mm peek fan.

geneb wrote:That's not true. That's what happens when you over-temp (247C+) the hot end. The PEEK fan is there to keep the cold section cool so you don't have PLA jams.

g.

Drat. I wasted 20 seconds posting that great picture just to find out that I was wrong.
Thank you for correcting my error. If ABS only is printed then the Peek fan is not necessary?

Well... I'm still waiting for the replacement fan, but in the meantime not one clog. I have other bots... one is the Flashforge Creator. It uses a non threaded thermal tube... metal with the teflon tube lining... no peek. It has fans on a heatsink which do virtually nothing. They are there because they copied the Rep1 and the Mk7. The orion's Peek has fins and the barrel is moved through the air so some cooling has to be happening... Not one clog since i removed the cowling. but... I'll put the fan back when it arrives.

BTW... I would NOT run a bot over 230c with a teflon tube lining. Teflon is not rated for much over 245C and even Bridge Nylon needs 250C. if you are going to run Nylon (which i do on my other machines) I'd recommend upgrading to an all metal extruder.

run a fan or you will likely have PLA jams.
btw, even for ABS I think the fan keeping barrel cool helps you have better retractions.

nice hot end Eagle. did the thermistor pop out or what?

bvandiepenbos wrote:run a fan or you will likely have PLA jams.
btw, even for ABS I think the fan keeping barrel cool helps you have better retractions.

nice hot end Eagle. did the thermistor pop out or what?

I think that is what happened. I found the image elsewhere on the forum and I think the
peek destruction was caused by a thermistor coming out.