bamboo backed hickory

[Mafort]

so i have a question. a buddy has a strip of bamboo that hes flattened and planed to glue up to the back of a bow he was bulding but he decided to sinew back it instead. hes giving this strip to me. i was wondering if i have a hickory stave floor tillered to say 55 lbs of draw weight what is a ball park estimate of the draw weight increase i can expect with the backing???

[tattoo dave]

There's no way to tell.It'll be enough of an increase, you will have to re-tiller, and could really have a new target weight. Basically it's like starting over. Hope that helps.

Tattoo Dave

[Mafort]

There's no way to tell.It'll be enough of an increase, you will have to re-tiller, and could really have a new target weight. Basically it's like starting over. Hope that helps.

Tattoo Dave

that explains it perfectly. i appreciate the reply

[Bayou Ben]

I would estimate 10 to 20 pounds, but it's just a guess.
Like Dave said, you will have to retiller for sure.

[Pat B]

You'll have to flatten the back of the hickory bow to accept the boo so no way to tell how much weight you'll loose doing that.

[Stick Bender]

Ben beat me to it I would guess 85 lb or so  depends on length of the bow & other factors , I just measure my 68'' ,48 lb @ 31'' BBH bow and it's ruffly 1/2'' out of the fade , you might want to thin that bow a bit and glue in some reflex for a pepper bow ,I love the BBH combo fast and durable combo it's one of my favorite natural material bows !

[Stick Bender]

I posted at the same time as Pat but if I remember right my hickory core started out at a hair over 3/8'' Pats right you need to get the core back flat  the closer you are to having every thing right at glue up the easer is to tiller and a nicer bow !

[Mafort]

sooo if i was aiming for a bow around 70-75 lbs or so at 28" what would i tiller my hickory wood core out to be??? i have a really good flat back on this one so im wanting to do it right. my buddy that i hunt with every year is wanting to hunt traditionally before he starts building them himself. i use a 75 lb ELB style yew wood bow that ive had for years. and he literally loves that bow so hopefully i can surprise him with this hickory and bamboo one. i also appreciate your guys help.

[Mafort]

would i be ok tillering the bow down to 40lbs and then backing with bamboo to get the 70-75lb draw? the length of the bow is 64 inches long right now.

[Mafort]

also do i sand down the nodes? that sounds like it would weaken the backing.

[Stick Bender]

I have no idea for a 75 lb bow maybe Ben will chime back in but with these lam type bows there is a lot of guess work involved some times it also depends on design and reflex and pre taper to get close to the weight you want  , if I where in your shoes I would flatten the back and glue in 2 in. of reflex and see where your at you can always remove more wood , I don't know if any body can give you a definitive answer on weight particularly sense your using a stave vs  pre tapered lams !  If your at 55 lb at floor tiller you have plenty of wood to go so your in good shape !

[Stick Bender]

No don't sand down the nodes your right you will weaken the back !

[Bayou Ben]

The most you'll want to do to the back of the bamboo is remove the rind, and some light sanding.  Not sure if your buddy did that already.
 
Hopefully someone with more experience than me with heavier bows can comment on starting dimensions for you.  If I was doing it, I would start with hickory .75" thick and see how much force it took to bend it a few inches and go from there.  Never made one that heavy. 

[BowEd]

When I did BBO's and BBH's I start out with a 3/8" thick core with 1/8" thick bamboo on a 64" long bow.At that time it's easily 65 pounds right off the form.Those were D/R bows 1 and 3/8" wide @ fades.Straight Line taper to 1/2" wide tips with a moderate reflex of a couple of inches induced past the back of the handle into the outer half of the limbs.

[Pat B]

I'd glue it up and remove wood to achieve the desired weight instead of trying to guess how far to tiller before hand.