Hi all,
Well, I guess there are many factors that contributes to the actual air flow need, but it seems like many people use very big fans. Just wanted to mention that my home built brake drum forge uses a small fan - 31W (~1/24th hp), 2"x2" outlet and 1.8 cubic meters/minute max. That would correspond to some 50cfm or so, and hopefully a picture of it will be visible below.
This fan has a built-in airgate, but another tip would be to use a simple fan control, like the dimmer type. That way you can easily adjust the flow from full speed to standby mode.
For a bigger forge a bigger fan is needed of course, and one cheap source of such fans is discarded oilburners for house heating.
Another thing that I
