Has anyone tryed making one of these? One is illistrated in Ray Mears book, Bushcraft. I made one today out of 2 pieces of willow and a 1 1/2' piece of natural cordage. It consists of one piece a foot long smoothed stick 1/2 " diameter for the drill, a squared flat piece 6" by 2/3" by 2" with a hole for the sliding bit and a 1' by 2" by 2" squared up piece for the 'fly wheel'. Both the sliding piece and 'fly wheel' have holes through the middle and the former has a small hole on either end. Through these 2, goes a piece of cordage with then threads through a hole at the top of the shaft. All this was done using a Mora Clipper and the small holes were done using one blade of some thin scissors. I know this is a terrible discription. Here is a diagram that helps a bit. The disk that they use is, on mine a foot long piece of timber. It is difficult to make using primative tools (NO DRILLS!), but satisfying. I will try and take some pics if you're interested.
Give it a go.