remote fan placement

[dbarrans]

I haven't installed any fans yet on my RMax. I've been considering whether the extra weight and possible vibration would reduce print quality. I wonder if there's a way to put a fan on the extruder mount, with a lightweight air duct routed alongside the bowden tube to get air to the thermal break, to avoid adding weight and vibration to the hot end platform.

Has anyone else tried this?

- dan

[Highcooley]

A simple fan (at least a PC fan in the range from 40 - 120 mm) won't have enough power to press enough air through such a long tube / duct. Additionally, a fan duct would probably be ways too heavy compared to a small fan mounted to the platform. If you have access to a compressed air supply, this would be a completely different story. You could mount a decompression valve to the extruder and rout a small tube to the hot-end, followed by a little diffusor and a duct to widen the airstream.

So far, I haven't discovered any vibration issues on my prints with two fans mounted to the carriage. One fan even constantly changes RPM during print. However, I had the same reservations in the beginning. But touching the carriage during print revealed a lot of other vibrations due to the stepper motor control and the whole mechanic construction. However, in a future hot-end mount, I would probably try to mount all the fans completely horizontal to reduce centripetal forces during XY movement.

[theverant]

I was thinking of using some small ducting instead of fans as well, but as Highcooley mentions about air pressure, it might be difficult to have an efficient system with small ducts without large/noisy supply fans. For now I'm going to stick with small fans close to the action. If you are worried about vibrations, maybe some silicone isolating grommets/mounts like they use in high end PC cases for fans?

However, in a future hot-end mount, I would probably try to mount all the fans completely horizontal to reduce centripetal forces during XY movement.

Do you mean the fans would be moving air in the Z axis? Would you use some small ducts to reroute the air? I was thinking of making a shell to guide air around the PEEK and up and away from the print nozzle, maybe sealing the space at the bottom between the PEEK and the shell with some of my left over high temp gasket maker. So I could have the fan mount in the way you describe blowing down into the shell.

[Highcooley]

Yep, I was thinking about something like that.

However, I wouldn't want to seal the duct completely with gasket maker. The hot-end should still be easily accessible and therefore the duct should be easy to disassemble. I imagine a two part duct with a hole for the hot-end.

Airtripper did an awesome job for a J-Head hot-end for his sumpod. A simple shell around the hot-end:
[img]http://airtripper.com/wp-content/upload ... racket.jpg[/img]

In his case, the duct is a mounting platform as well as a bowden tube fit at the same time.

[mhackney]

I mentioned this in another post yesterday - I use a 25mm fan tucked between the hot end mount and delta plate:

[img]http://mhackney.zenfolio.com/img/s8/v75 ... 2480-3.jpg[/img]

It is a perfect press fit, no glue or anything holding it in. You could always use a set screw from the top. I have it wired to my LEDs so when I flip them on, the fan is on. It is aimed directly at the PEEK section of the hot end and blows quite a bit of air. I am taking temp measurements on the back side of the PETE with no fan and with fan so I can show how effective the cooling is.

regards,
Michael

[mhackney]

I have temp measurement info in my build thread now: http://forum.seemecnc.com/viewtopic.php ... 106&p=5813

[Highcooley]

Is your 25 mm fan more or less silent like a 40 mm one? The only 25 mm fans I've ever seen where very noisy (air swoosh).

[mhackney]

It's not dead silent but makes a very low kind of hum. When the machine is running you can not hear it at all.

[Highcooley]

Cool...then I definitely want one of these