Thickness of Belly Wood - when glueing wood to bamboo backing

[outdoors4me]

Hey folks,

New builder here trying to trace down a problem with my bows not having enough backbone coming straight off my glue up form.

What thickness do you start with on your belly wood? I know this could vary with type of wood. In my case, I'm using Yellow Heart backed with bamboo.

I've already made another post about wood grain orientation as well.

Thanks much!

Beck

[Pat B]

I personally wouldn't start with less than 5/8" thick unless you plan on using a power lam.
FYI, a power lam goes between the back and the belly at the handle to keep the handle area rigid.

[outdoors4me]

Thanks Pat!

[BMorv]

I've worked with YH a good bit.  Pat is right on with thickness.  I would start at 5/8".  Mine usually finish out right under 1/2" thick, but that can obviously vary with your design. 

[outdoors4me]

5/8" inch it is!

Thanks,

Beck

[Roy from Pa]

Yup, 1/2 to 5/8th for YH.

Osage I did 7/16th to 1/2.

[outdoors4me]

OK, here is the reason why I asked....

I recently took a class on building longbows.

The instructor gave us a bow(stave) in class that was already glued up. 3/8" piece of yellow heart glued to a piece of bamboo. It had plenty of backbone and I ordered another just like it from his web site after the class and it had plenty of backbone.

I noticed in his earlier published plans that he USED to use 5/8" thick Yellow Heart. So I wonder if he can tell by looking at the wood before it is  cut as to how strong it's going to be.

The reason I'm stumbling through all of this is by all signs (website down, phone disconnected) he is out of business. I can no longer reach him for answers.

So I thank everyone for their help here.

Beck

[Roy from Pa]

Were the first 2 bows from him 1/4 sawn?

[outdoors4me]

Roy,

Unfortunately I don't know and I can't ask him. Those two bows are finished and I can't really look at the grain on the end to be able to tell.

Is there another way just looking up and down the bow to tell?

Thanks, Beck

Were the first 2 bows from him 1/4 sawn?

[BMorv]

I don't see how a decent weight bow was made from a .375" thick peice of YH.  Do you have pics of both bows? 

This bow came out 45 #'s and started out .550" right out the fades.

[Roy from Pa]

Looking at the belly of the bow, the side facing you when shooting.

1/4 sawn will have long straight growth rings running the length of the limbs.

Flat sawn will look like arrowheads.

[Roy from Pa]

1/4 sawn board on right side.

[Pat B]

I've never used yellow heart but I always start out thicker and reduce the thickness as I tiller the bow. That way I'm assured I achieve the draw weight and proper tiller I desire.  I don't make many backed or trilam bows so I'd rather air on the side of safety starting with a thicker piece of belly wood than someone that makes these bows on a regular basis, like Roy and others.

[outdoors4me]

Trying to post pics but it won't let me. Not sure if it's the size or what. I'll keep trying....

I don't see how a decent weight bow was made from a .375" thick peice of YH.  Do you have pics of both bows? 

This bow came out 45 #'s and started out .550" right out the fades.

[outdoors4me]

Thanks Pat!

I've never used yellow heart but I always start out thicker and reduce the thickness as I tiller the bow. That way I'm assured I achieve the draw weight and proper tiller I desire.  I don't make many backed or trilam bows so I'd rather air on the side of safety starting with a thicker piece of belly wood than someone that makes these bows on a regular basis, like Roy and others.

[outdoors4me]

Wow, that's certainly easy to see.

Thanks Roy!

1/4 sawn board on right side.

[Roy from Pa]

If using a cell phone for pictures, you need to go into the phones camera settings and choose the smallest size picture it take.

Cell phones take humongous size pictures for some reason..

[outdoors4me]

Ah! I'll reduce them in Lightroom and try again.

Thx

If using a cell phone for pictures, you need to go into the phones camera settings and choose the smallest size picture it take.

Cell phones take humongous size pictures for some reason..

[outdoors4me]

These both started out as 3/8" and now are about 5/16". Hard to believe, but I can't even string the one finished in oak without a stringer device. The purple one I can barely string on my own.

Beck

I don't see how a decent weight bow was made from a .375" thick peice of YH.  Do you have pics of both bows? 

This bow came out 45 #'s and started out .550" right out the fades.

[Roy from Pa]

Ya know there will be a $19.99 fee for all this info, don't ya?

LOL Just kidding..