Broken Fans

[CNCCookbook]

Got the Rostock working fairly well over the course of about 3 1/2 weekends. Minor issues here and there that could be improved upon, but no biggies. It's all chronicled starting here on my blog:

http://blog.cnccookbook.com/2014/04/21/ ... er-part-1/

Last weekend I went to install the fans. I'd printed some parts that came out nicely, but it was time to at least get the PEEK fan going. This is where I learned just how easy it is to break the tiny PEEK and layer fans and not even notice. When we went to light the fans up to test them, the Layer Fan ran noisily but not reliably. Depending on where it came to rest, it was possible that it would not be able to restart without giving it a push. The PEEK fan wouldn't run at all and we spent a fair bit of time fooling around trying to figure out why.

The problem in both cases is that while the fan enclosure prints looked just fine, they were WAY too snug. The fans are delicate and if the enclosure is too snug you can wind up pinching and even breaking their frames. We had broken both and there was no real cure (short of printing your own new frame as I saw someone else with the same problem did) but ordering two new fans.

Best fixes for this:

- Look at making the models for the fan enclosures a little larger so things aren't so snug. We did considerable filing on the layer fan enclosure to get to the point where it was snug but not fan-threatening, so I believe there is room to do this.
- Add a caution to the manual to let people know they need to take care and possibly file or sand out the enclosures. The PEEK fan in particular doesn't need a tight fit as the way things work it isn't going anywhere. A loose fit might be a lot more desirable.

You could redesign the layer fan slightly to accomodate a looser fit too if there were a couple snap tab outriggers to hold it in place.

Overall, this thing is a fantastic value, I'm just trying to provide feedback so that v3 or whatever you want to call it can be even easier for anyone who wants to build one.

Cheers,

BBQ

[geneb]

Over-extruding will cause the same issue.

g.