bamboo backed help needed

[fujimo]

i am busy tillering a bamboo backed hickory bow.i heated and reflexed the board, then laminated the bamboo onto the board- the boo was tapered to the tips- so it is of a uniform thickness, fade to tip.
alls gone really well so far(thanks everybody for all the help thus far)
BUT. my worry is that i may have gone a bit wide on this bow, used the same proven design that i have used on other hickory board bows-
1 and 7/8" wide fade to mid limb, then tapering to .5" tips.
now that i am tillering , i fear that i am going to get really thin on the hickory.
 now how wide should a boo backed hickory bow be, and yet still not acquire too much string follow. etc
thanks wayne

[Pat B]

You can remove wood from the sides on a boo backed bow. Can you post a pic? That really helps to see what we are dealing with.

[Bert Frelink]

Wayne,
How thick is your Bamboo? and how much did you taper it?
I am with Pat, just take a little off the sides.
Just bring it over and I will get the BIG axe out and trim her up a little for ye.  
Bert.

[gordonf]

How long is the bow? Is it a stiff handle design?

[Roy Steele]

Depends on bow leanth,weight,bamboo thickness.
   As for me yes even backed, a thin bow has to have better tiller.Backed bows can be a little thiner but this isn't the reason I back bows.

[fujimo]

72 " long, with a stiff handle design, 4" inch handle, with 2" fades, 1.5" of reflex. 1 7/8 " wide.
i have a 28.5" draw length. the bamboo was tapered right to a point right around prior to lamination, with the boo cut to a slightly oversize profile matching the bow., after lamination, and trimming to size, i geuss its 2- 3 mm around the edges.
the hickory is about 6mm (1/4") thick in the working areas of the limbs, and i am only at about 4" on the long string.
[Bert, the design was kinda based on those hard working, straight shootin' laminated bows that you build- maybe i do need to drive down south to where the big axe lives.]
will try to post pics today, am awaiting feedback from trad gang as to how one does the pic thing.
thanks
wayne

[Pat B]

At 72" long and 1 7/8" wide you should be able to remove wood from the sides with no problems and reduce the length unless you wanted a longer bow. You could make a 200# bow with that set up.
   At 1 7/8" wide I believe your boo's crown thickness it too thick. Most boo backed bows I've done(which isn't many), the width was about 1 3/8" at the fades so the boo thickness at the crown, at the handle is only about 1/8" thick and the edges of the boo are razor sharp. I also taper the boo from handle to tip, but only after cutting the boo backing to its ultimate shape.

[Bert Frelink]

Wayne,
Did you taper the thickness of the Bamboo at all?
It sounds to me you are overpowering the Hickory.
Hickory is not very tolerant of compression, I would say you could take the sides down to 1 1/4"
easy, I will warm up the BIG axe        for you anytime.
I also have Dean's video I could lend you, if you promise you won't keep it for two years   :eek:  
Have fun and just go slow, I am sure you will figure it out!  

[gordonf]

I'm with Pat on this one. 1 7/8" is much too wide for this design.

[fujimo]

thanks guys that is what i thought. i had tapered the boo to razor sharp edges all round after it was cut to its final shape.
geuss i will slowly take the sides down till i get what i am looking for.
thank you all very much.
wayne
ps.
bert.
i might come and see you on sunday pm. if that works for you.
dont want to be a hassle.
wayne

[Pat B]

At 1 7/8", even with the edges of the boo at  razor sharpness the crown will be too thick and this is where the strength is. You may have to trap the back edges of the boo to reduce its tensile strength a bit after you reduce the width.

[Bert Frelink]

Never a hassle Wayne,
See you on Sunday(I will warm the big axe up for you)
   
Bert

[chrisg]

Yes taper the boo. A wide limb is stable but boo is not like glass lams, so take some off each side too like Pat said, there is enough length there. I get it so thin it is almost translucent to the point it will almost curl giving a concave glue surface. Wide boo is real thick in the middle and even if you have thin edges it is amazing how thick the middle stays. We used a curved scraper once on a particularly thick and curvaceous piece. The trouble with too much pith is it makes the glued lamination like a great thick chunk of iron and then when you finally get it down near your intended weight it either gives up all its power at once and you come out under weight or else it ends up so narrow that it is a risk to shoot. Dean's dvd/video is the best. That and a big axe waiting in the corner        

chrisg