I thought I might post a little history about where the mass theory came from and why I came up with it in the first place. Tim Baker actualy started it. His mantra was, " make the limbs wide enough near the handle to take no set, mid limb just a little set" I used to pester him and say how wide is wide enough? Tim then came up with a bending wood test and posted a way to apply it to a bow, it seemed to work pretty well but I used to get confused trying to figure out how to use it. Then they came up with wood charts noting typical bending properties of different woods. You get the picture here, there were several of us trying to figure out how wide to make a bow. We would e email back and forth, talk on the phone, argue, challenge then back to the drawing board. Just prior to the mass principle and something I still use I came up with something called
" no set tillering" it is much more accurate than the mass theory but not as quick and easy to use and the differerence in results are not dramatic, I actually use them together now, I use the mass theory until I am about 16" into tillering then switch to no set tillering. The mass theory tells me a lot about the condition of the wood, too light I am too dry, too heavy I am too wet. I have to admit that there was a bit of ego attached to this, finding the magic formula for width had become like th eholy grail to a bunch of us and had actually become my major challenge in bow building. I felt like I was in a race to get it before someone else did. It was trail and error all the way. I got it to work pretty well on pyramid bows but found that didnt work for paralell limbs, every time a bow changed the mass I needed seemed to change with it. It took a while before I finaly recognised that everytime something on a bow changed I needed to adjust the mass accordingly because the strain on the wood was changing. Once I planned away to assault the problem it came together pretty fast.
I built about 25 pyramides of all different lengths, about 25 elbs of all different lengths and about 25 paralell limb bows all different lengths. Once they were all roughed out I started finishing them all of using the no set tillering method which I will explain here. All the bows in the group that were successful performance wise and no set wise I averaged out and just played with the numbers till I found simple formulas that seemed to average out pretty well. From that point I spent about another year just perfecting it the best i could and trying to plug all the holes I could find.
The no set tillering is pretty cool I think, you don't measure mass at all. you simply start tillering as you normaly would but use your scale to monitor set. You actually pick up on it before it is visble. When you put your bow on the tiller tree just carefully note what the draw weight is at a specific distance, say 16". now as you pull it to 17" you go back and check 16 to see if it changed, then go to 18 then 19 then 20 each time going back to 16 which has become your benchmark and looking for the slightest change. If you note a slight change examine your tiller closely and remove a bit of wood to reduce strain, Now make a new benchmark at your last place you pulled to and go on tillering each time going back to the last spot and checking the weight. Anytime you see the slightest drop in weight at your benchmark you take off more wood on the belly, taking wood off the sides if you need to drop weight. If you compelte the bow and get zero set which is rare you will be shocked at how it shoots. Not hard to gt less than 1" using this method.
