This is my favourite tillering tool. It has a 6 inch flexible head which follows contours perfectly. You can take off minimal amounts of wood by selecting low speed, or more on higher speed. I use 80 grit, so that it's still pretty smooth. When I reach final tiller, I can immediately step up to hand-sanding with 100 grit, and on up from there. This thing is awesome: a rasp and smooth file and scraper all in one.
With this 2nd firehawk bow, I used a new method of tillering which some people may think is pretty strange: I removed wood from the back! My hickory backing strip was 3/16 thick. I wanted to keep as much osage as possible on the bow. Also, i get tired of taking the string off all the time. So i would check the tiller, decide where wood was to come off, then take it from the back. Once I reached the good bending shape I wanted, I simply removed wood from the entire back, by marking it with pencil from fades to the inboard side of the recurve, and sanding until the pencil was gone, with the sander on half-speed.
This meant I never had to take the string off, and could simply lay the belly of the bow on those two 2x4's i have sticking out from my bench top, the string underneath.
Once I reached a brace height where I could sand the belly without removing the string, i did so. There were a couple small knots in the osage that were causing stiff spots.
I reached tiller on this thing in a few hours of careful work. 60# at 28".