Here is a formula that I use when making bows ,that I discovered my self!!! It is only a rough guide but I have found it quite usefull. It comes in after the floor tillering stage. If you make a string the same length as your bow (ntn distance) and start bending it on the tillering tree, then the weight needed to pull it far enough to put a real string on (at a 6 inch brace height), will roughly equal the bows weight at full draw with the real string, with a few pounds extra, to give room to adjust the tiller. I find this stage critical. This helps me to avoid bending the bow when it is too heavy thus not over straining the wood and to get the bow dimensions as close to final before bending the bow. I would hate to be responsible for anyone ruining a bow so please dont rely on this ( not that anyone probably would ) But I would be interested to get some feed back if it has any value or not and maybe I could have added something usefull to the bow making world