I followed the guide in jon mcphersons book and it doesn't explain exactly what backing it was for so thanks.
My bow is 6.5 inches, before I put sinew on at full draw it had 46 pound draw, after adding sinew its up to 54 pounds, it said in the book this would happen.
As I understand it a bow of 50 pounds is good enough to kill a deer? Obviously im not going to use it for hunting but the ability to make a tool to take town such an animal is important to me.
I've never used a bow in my life but I fired 30 arrows today and I can hit a hay bail at a decent distance so im happy, though after 30 arrows I've lost 2 lbs of draw weight. Is this normal?
Sorry bud just had 3 days in bed due to the lovely NOVO Virus and still resembling something from the walking dead series.
Let me start by saying any bow that can launch a hunting weight arrow about 140+yards would do the job. Probably less to be honest. The reason you cannot say that a given lb of draw weight can kill or not is its all down to performance per lb. I have 40lb bows that I have made recently that out-perform some of my 50lb bows from way back so its all about cast. I would think that your bow if even roughly designed well would be more than enough to drop a deer, given a good range and sharp heads. Whilst i have never hunted my self (UK) the numbers make sense.
Going forward for performance sake there are a few factors. 77 inches is way too long for a sinew backed bow. The reason for this is sinew is heavy compared to wood. So more mass = less cast. Wood alone still performs better than sinew lb for lb is one way to think about it.
Sinewing a bow will add draw weight as its dries and this can carry on for a month or two.
If you are loosing a bit of weight it could be that the sinew is either not dry or you have a design problem in there some where.
One clear indicator of a design problem is studying the braced and unbraced profile of the bow just after un-stringing. If the profile is changing evenly along the whole length of the bow then its probably ok and providing it doesn't carry on changing its probably just a little set. If one part of the limb is changing only then you have a design problem and a possible hinge developing. It can actually be possible to raise draw weight and performance by "piking" the bow (cutting a few inches of each end) and re-tillering providing you have enough width.
Get some pictures up of the bow unbraced, braced, and at full draw. Also a picture of the back of the bow would help.
This is why we all tend to post these pictures to show our bow making buddies across the world, not because it looks cool shs, but because it tells us everything we need to communicate the feel of the bow across the web