Ver good point, Steve. I've recently been applying this technique as well. Basically the "no set tillering technique". Draw to a certain drawlength and record drawweight. Pull a few inches further to excersize the limbs, and return to the same drawlength as before. Have you lost drawweight? Then the bow must be taking set.
A friend and I were tillering a black locust bow. The bow had already taken some set (maybe 2 inches) early on in the tillering process. Yet the design appeared in accordance with the drawweight he wanted and the tiller was spot on. He could not tell me where the set came from, but he was worried he would end up with 4 inches of set by the time he reached full drawlength. We put the bow on the tillertree and pulled it to the maximum drawlength he had pulled it to thus far, which was 22" maybe. We accurately recorded weight at the drawlength, using a digital scale. Since the tiller was good, we decided to pull it further, so we excersized the limbs several times up to 24". We returned to the same 22" again (without removing wood) and measured the drawweight again. We lost maybe 0.2 pound. Nothing to worry about, so we pulled it to 26" several times. Again, we measured the drawweight at the inital 22" and we lost about 0.4 pounds. This was a clear indication that the bow was hardly taking more set. So we continued tillering (which was not much) and came at 2" or maybe 2½" of set at a very acceptable drawweight.
We still don't know what caused the initial set up to the 22" mark, but the "no set tillering method" clearly indicated we had nothing to worry about from that point onwards.
