Boo backing Osage?

[Hawkdancer]

Should have pics, but!  What amount of fitting or matching is needed between the osage back and the "boo" belly? and how do you avoid violating a ring?  Also, when can you change from a fade handle to a glue on lam handle?  Won't be able to get pics until tomorrow evening.
Hawkdancer

[Dances with squirrels]

Yeah, gonna need pictures for this one. Osage back? Boo belly? Did you say that backwards maybe?

[Dances with squirrels]

Are you talking about fitting a bamboo backing to a standard osage selfbow stave with a crowned back? Or are you talking about putting a piece of bamboo on an osage board? Or something else maybe?

Either way, the fit should be very, very good. No gaps.

Also, while relatively straight grained, clear wood with minimal ring runout should be used, imo, if you're backing with bamboo, violating growth rings of the osage while flattening the back is of no concern, and just part of the process.

[Eric Krewson]

You have to flatten the osage back like a board don't worry about the rings, bamboo becomes the new back.

The key is to have a very thin bamboo backing. You should shape it perfectly to the shape of your intended bow and have about 1/16" thick edge from the handle to the limb tips.

Back in the day I did the bamboo thinning with 60 grit paper and a sanding block, I use a belt sander now with a 36 grit belt.

[Hawkdancer]

Yeah, gonna need pictures for this one. Osage back? Boo belly? Did you say that backwards maybe?

Yep!  Must be getting "dumb attacks"!  Or senile dyslexia, or fat finger disorder! . Thanks for the replies!
Hawkdancer

[sleek]

I use a belt sander. Some ( ok lots ) of folks say the bamboo needs to be thin. I honestly dont know why. I use narrower bamboo that has a crown, and it's not possible to make it thin without also making it narrow. So, I just get it flat and glue it on.

As a side note, with bamboo, I noticed if you use tight bond to glue it, the boo soaks up LOTS of the water from the glue. Even after the glue has dried, the bow is weak and doggy. But, give it a couple weeks to dry out and the bow really comes to life.

[DC]

Things I've found when doing backings. The belly has to be flatish. It can wave up and down a bit but no sudden changes. The narrower the bow, the thinner the boo can be. The thinner the boo is, the more flexible is is and the better it conforms to a "wavy" belly. The larger the diameter of the bamboo "tree" the thinner the boo can be for a given width. Up and down waves are not a big deal but side to side are a no-no. I use bike tire strips as tight as I can and cover the entire bow with rubber. I put on a first wrap spaced about 2" apart so I can see that the glue line has closed up and everything is OK then I put on the second continuous wrap. if you live in a sunny area stand it out in the sun for a good fast epoxy cure. You don't have to worry about minor grain runouts on the belly piece but it still has to be good wood.

[DC]

Some ( ok lots ) of folks say the bamboo needs to be thin. I honestly dont know why. I use narrower bamboo that has a crown, and it's not possible to make it thin without also making it narrow. So, I just get it flat and glue it on.

I agree. I only make it as thin as I can so it conforms to the back better. I get a better glue line that way. Since the SG of the boo drops as you get away from the "power fibers" I don't see any weight advantage to making it thin. If you're recurving it thin boo at the tips bends easier. For me the diameter of the boo tree and the width of the bow determines the thickness of the backing.

[HH~]

I like the way James P. The wild man himself does his Boo. Best i have ever seen. He thins and squares it where he needs too. One need to just look at his and it will become clear.

I did my own boo for years from a yellow boo thicket growing 60-80ft tall. I use to cut it, sand it, square it and fire it. Started using green boo but quicly found standing dead was top notch. Just have to cut during dry season. Bigger dia boo wider and thinner backing you can make.

Using good lamination glue goes a long way to a good lam. If you high end lam epoxy you dont need a perfect glueline. Use cheap wood glue, you better have a great glueup surface!

 Doing them on a stave back can be tricky but once you do a few its ok. Way tuffer than gluing up to a board however. Osage or Lemon or Orange tree backed with boo is hard to beat. They are fast!

HH~

[Eric Krewson]

I have made over 50 bamboo backed bows and found if you don't thin the bamboo a good bit you end up with a osage belly bamboo bow instead of a bamboo backed osage bow, very little osage on the belly. I don't use the commercial Mosa which you can get a flatter wider slat from. I use Mandrake 4" to 7" in diameter that I cut locally, it will have a higher crown and needs to be thinner.

I like this ratio on my bamboo backed bows, the osage is 1/2" thick, the bamboo is less than 1/8", this is right after glue-up. I will round the bamboo edge on the finished bow to be a knife edge;

[sleek]

Ok Eric. Riddle me this. What's the difference between an osage bellied bamboo bow, and a bamboo backed osage bow? I've often wondered.