a crack.... i think

[John Scifres]

How thick is that boo?

[Pat B]

The ipe would be better!

[n8-mac]

width of bow at fret.  

thickness of laminations at fret    

[Eric Krewson]

Your bamboo is way too thick.

When I make a bamboo backed bow I make every edge 1/16" thick. That is, if you look at the backing from the side you will see only a 1/16" tall edge. It will be the same edge thickness from the handle to the tip.

By keeping this thin edge you will naturally taper the bamboo thickness from where you start the taper to the tip and won't overpower your core wood.

What you have is what I call a "hickory bellied bamboo bow" instead of a "bamboo backed hickory bow". Made a few of these myself when I was trying to get the poundage down and ran out of belly wood because I left the bamboo to thick.

[Eric Krewson]

Here is how thick your bamboo should be for a backing. The osage core to the pencil line is 7/16" thick, the bamboo is 1/16" thick on the edge.

 

[stringstretcher]

Eric.  Is that bamboo backing, facing me in the picture ground flat?  No nodes?

[n8-mac]

Is that a laminated boo?  I am using a "full" piece of bamboo.  is there a difference in its strength?  i have not sanded off the nodes either. It seems if anything it would be stronger as a laminate..?

[Eric Krewson]

Nope, just plain old bamboo, nodes and all and rind intact. The bamboo in picture is the thin strip below the osage. The bow is 1 1/4" wide

Here is the where this bamboo came from, the corner of my shop, little green in this picture.

 

[stringstretcher]

Man I need to have my eyes checks.  All I see is a piece of osage with a pencil line on the top of the picture, and what looks to be a piece of hickory grained wood on the bottom.  I know I am loosing it, but I sure don't see any rind or bamboo there.

[horseapple]

Its bamboo, you can see the power fibers on the edge, just left of the pencil mark about a half inch.

[Eric Krewson]

Backed off a little for this shot of my glue-up to prove it is indeed bamboo, just properly thinned bamboo. This type of bamboo keeps a green hue on the rind but had a beautiful caramel color after the rind is scraped off.

 

[stringstretcher]

Now I see it.  I apologize if I offended you Eric, never doubted it was not bamboo.  I just saw it as wood grain.  Thanks for the picture and as always, great work.

[Eric Krewson]

No offense taken in the least, I just like to show off my stuff.

[stringstretcher]

And I am so glad that you do.  Anyone would/should be honored to have one of your bows.  When does mine go out????              

[stringstretcher]

Boy that put a halt to this thread real quick.  I was only saying, not asking, that your equipment is top notch Eric.  I learn from you on every post you participate in.

[n8-mac]

Eric,
could you post a pic of your bows profile up close at the node. I am amazed that your boo is so thin.. i dont beleave that i have the skill or the tools to make such a thin lamination. other than the lamination thicknes your boo looks the same as mine..    is there a reference table that has some general wood characteristics such as compresion and shear or reflex strength?

[Eric Krewson]

I have a 6X48 belt sander and use 36 grit sandpaper to do my final thinning on a bamboo slat.

Before I had the 6X48 I used a elcheapo delta 4X36 to do the same thinning.

Don't understand your picture request. I space the nodes as evenly as I can on the top and bottom limb. I don't make allowances for nodes as far as limb profile goes.

My profile is about the same bow to bow. 1 1/4" wide to just past mid limb and then tapered to slightly narrower than 1/2" nocks.