increasing selfbow poundage?

[Ian johnson]

I have a hickory selfbow that pulls 45# I want it to pull a little bit more, would adding a set of copperhead skins increase poundage by a few pounds?

[the Ferret]

No, you could add a layer of sinew, or shorten the bow an inch on each limb and that would gain you between 4 and 8 pounds.

[John Scifres]

Increasing weight for the sake of it is not a good idea.  If your bow is overbuilt, you may be able to tweak some more performance by increasing weight.  That along with other performance enhancements are really the only way to make a better bow from one that came in under.  Give us some details on what you have and maybe we can help make it the bow you want.

[Jeremy]

You could add a cable on the back.  I've increased the weight by 8# with a twisted cable, and decreased the tip width and thickness (to maintain tiller) in the process.

[the Ferret]

Jeremy, got a pic? Love to see it.

[Jeremy]

Ferret, no pics of that bow.  It had so many problems it wasn't even funny!  It was a "tillered" blank I bought a few years ago with so many knots on the belly it looked like bird's eye!  Crysaled *badly* while shooting it in    

The process was pretty straightforward.  I wrapped B50 endless loop fashion around a second set of knocks a few inches from the tip, bound the loops to hold them on the bow, put a stick between the lays and twisted it up. I tied the stick in place to keep it from coming untwisted (and used it as an arrow rest) and glued some leather "v" shaped pieces on the back (under the cable) to keep it centered.  

Hmmm... might have to make one that way on purpose...

[Ian johnson]

john scifres, it is a hickory d shaped very long,  flat bow,it starts out really wide at the handle, then tapers to a point at the tip, is snakeskin only decrative?, what does it do to the bow?

[Mulberry River]

I think it's used for a waterproofing layer over sinew backing, which is not waterproof.

[gordonf]

You may be able to add some draw weight to the bow by heat tempering the belly. Doing so will will require some retillering though.

Snakeskin is usually applied for purely decorative purposes. It is, however, waterproof, and will protect a sinew back from moisture.

[the Ferret]

Sounds interesting Jeremy. A take off on the Eskimo cable bows. Rusty Craine made one once, not sure how it ever turned out.

[John Scifres]

Let's start at the beginning.  If I wanted to make a rigid-handles, 50# @ 28" flatbellied, hickory selfbow, I would make it 68" NTN, 1-3/4" wide at the fades for half the limb and then tapering to 1/2" nocks.

It sounds like you have what is commonly called a pyramid bow.  It starts out wide at the dip and has a straight taper to the tips.  If I were to make that bow, it would be 2" wide at the dips and still 68" NTN.

That is an overbuilt by maybe 10% design.  To tweak efficient weight from an underweight bow, I would not hesitate to shorten it by 1" on both ends and retiller.  You may gain 4#s depending on how much you have to do.  The thing you can't do it make it whip tillered and gain only stack weight. Stack weight is a function of string angle and the resultant loss of leverage and doesn't do much to improve the efficiency of a bow, it just feels heavier and draws more harshly.  You need to make sure your tips are tillered pretty rigid to make an efficient bow or you aren't really helping yourself.

It would really help to get exact dimensions as well as desired draw weight and length.  A force-draw curve would really help tell if you can do much by shortening.  Those pieces of information and pics of the bow unstrung, strung, and drawn full would tell the tale completely.

Snakeskin is for decoration only most of the time.  There are some skins that are thick enough to protect a back from blowing a splinter but they won't add weight or efficiency.

Have fun,

John