I am currently tillering a 48" ntn flatbow. It is 3" wide at the fades and 3/4" wide at the tips, piramid shaped, with an 8" stiff handle. The draw length and weight is 30lbs. @ 24". This is a board bow that is nearly flat ringed. Because of the roundness of the rings combined with the flat board makes one edge of the limb flat ringed while the other edge is more bias ringed. I say this because I think it maybe contributing to my tillering problems. I have made a few successful bows, though never this short, and have read and reread every tbb book, esspecially the tillering chapters. I don't think it matters to my problem but I'll add anyway that I have been using the mass theory, calculating to be overdawn to ensure safety and durrablity. Now to the problem, at first, while tillering, I was being careful to keep both edges exactly the same thickness so that the limb would not twist, unfortunately it began to twist as soon as it was strung for the first time. When I looked down the limbs I could see that it was due to one edge bending more than the other, so to correct the problem I began removing wood from the area that was not bending as much. Then I exercised the limbs and rechecked the tiller but there was no improvement, so I tried again. now I have done this three times with no change except that one edge is quite a bit thinner than the other. I am worried that if I continue I will ruin this bow, and was wondering if any one had any advise.