Fan Ducts

I'm doing overhang calibration and am in need of some serious fan action in order to get these things to print properly.

I designed a funnel-like duct for a 50mm fan, and it worked terribly; the outlet was too small and no air was making it through.

So, then I grabbed a piece of paper and made a cone, and started experimenting with it. If the outlet is too small, no air goes through; with a big enough outlet, one can get some good flow.

Anyhow, I put the paper cone on the printer and did an overhang test, it failed, then I adjusted the cone, and now I'm getting an amazing print.
> [oi61.tinypic.com]
> [oi58.tinypic.com] (The small droop on the top layer is surely due to layer thickness and not cooling.)


What does everyone else find works really well for them?

I think that something like this would probably work well, by virtue of the large outlet: [www.thingiverse.com]

There are also fans with circular outlets in an attempt to cool evenly from all directions, but I'm doubtful that the flow through them is very good. [www.thingiverse.com]

Hey there kre8 thought I would check out your post about the test part you trying to print.

I use blower fan for part cooling wired to my control board so it changes speed when needed. Here is a Link to the type of fan I use. I had some laying around from old PC's on a video card so you might already have one.

This [www.thingiverse.com] has been found to work well for many people.

I'm impressed with the overhang that the ATOM can print [www.thingiverse.com]
So I'm going to try and mimic their fan design [www.atom3dp.com]

So, I made this cool thing [www.thingiverse.com] which doesn't work as great as I had hoped, but it's OK.

I ordered a pair of centrifugal fans a few days back, so those should be here soon. I think they'll be easier to work with.