Back in the day, when I first started, a lot of my bows would come in under weight and I would do this and that to get them to raise weight. I'd pike them mainly. Came to the conclusion I wasn't learning about tillering that way. I realized I was better off just starting another bow. So that's what I did and hear I am 23 years later. I don't come in underweight too much anymore. BTW cutting an inch off each end will get you 4-5# and more set so you haven't gained anything. It may also break on you if your tiller is not good. Yes, there is a formula. It's in one of Jim Hamm's writings. Also, it's a bit on the long side for sinew. You probably won't gain any significant cast. Linen may add some weight. Not much. Anyway, have fun. Sorry to be throwing in cold rags into the discussion. Jawge