Possibly the most compact, simple, cheapest and fastest iron farm.
Setup:
1. Waterlog the Mechanical Drill and the Andesite Funnel.
2. Apply rotational force to any point in the machine (64 RPM seems to be the sweetspot).
3. Watch the fan. If it sucks, reverse the source of the rotation. If you are unable to do so, change the 2 Cogwheels behind the fans to Encased Chain Drives or a Belt.
Instead of sorting flint, it is now left to despawn.
Previous version: http://createmod.com/schematics/simplest-compact-iron-farm
It has a cobble leaking issue. It's like 1/3 so pretty bad leak
Easily correctly by just doing a belt below it with a tripple fan setup for increased speed (yes makes it a bit bigger but more reliable
ChimeraGaming cobblestone leaking isn't really a big deal in this farm I believe, since the main bottleneck will be the speed of the Mill. Adding more fans to the design will do nothing as far as I know, since a single fan can process multiple gravel at the same time. As soon as you start making expansions on this compact design, it starts to become less viable, and you're better off using a bigger more industrial design. This machine was specifically made to be the smallest it could possibly be.