A friend came by this morning to tiller out his Vine maple bow, stav was good and clean with only a couple of knots that had been worked around safely. Wood was very dry at 7%. Goal for this 66" long holm garde was 60#. Tillering was going along nicely and then suddenly at 24" and about 54# she let go. Bow had shown no signs of taking set as it had been worked up with ony 1" increments of increased draw and break happened in a low bending area, close enough to a knot to raise some suspician but the break looked more like a shear tension type break, Bow was about 1 3/4 wide. At first I saw no obvious reason why the bow let go and just chalked it up to an invisble flaw or weak spot in the wood. I decided to weight the bow to see if it was overbuilt or underbuilt, Turns out the projected mass on the bow for desired draw weight was 3.5 oz less than actual weight indicating that bow was simply underbuilt and did not contain enough wood to make this design work. There were no clues as to stress because it was too dry to take set so it just simply failed in tension. Just for the heck of it might be worth while to weigh any broken bows when looking for the cause. I cant be sure this was the cause but I feel pretty strong it contributed. Steve
