Well i"m making a bamboo backed hickory r/d bow for my brother in law and Its all glued up and its about floor tillered. I thought I got the bamboo pretty thin but after I reduced the width to an inch and a half I realized that the boo is pretty thick. Its probably a quarter inch thick. Will this overpower the hickory and cause chrysals?

A quarter inch is probably gonna overpower the hickory. I try to get my boo to 1/8 max with a hickory core. You might trap the back and leave the belly as wide as you can and work it out. You can't thin the boo after glu-up. Good luck

James

Just as James said. I'd also suggest trapping the boo.
Ron

What glue did you use, Lee. If TBIII you can heat it and remove the backing, thin it and glue it back down.

Lee, also cutting the bamboo out to limb profile first and then sanding down to thickness will eliminate your problem.  If you sand it to thickness at full width, when you cut the profile out, you are cutting it back to a higher thickness.

Thanks guys! Pat how do you heat it? with a heat gun?

Yes. Start at one tip, heat it until you can get a screwdriver between the two then work your way to the handle. When you get there start at the other tip and do the same. I've done this on a few backd bows. I called TB to ask how to do it and they told me that any TBglue will release at 150deg(F).

I say try it as is Lee. We hear about thick boo "over-powering" cores, but we never see it? Prove us wrong and build a bow with it that thick. I have a bow with 3/16" boo over Ipe and its just fine.

One of my first boo backed bows was a trilam. I didn't shape the boo before thinning so the backing came out way thick. As I was tillering the bow started to take on more and more set. I trapped the boo backing to about 1" wide(limb was 1 3/8" wide) and it didn't take on any more set.
 I've heard it really doesn't matter but it sure didn't hurt anything to trap the back.

Pat I always get fidgety when I start messing with the edges of boo! Gives me the heeby-jeebys. Though I have never had a boo failure, I sure read about enough of them to make me a touch gun shy.

I don't use boo anymore because it can be so finicky. Between breaking at a node or lifting a splinter it just isn't worth the trouble of messing with it for me. I'll take a hickory backing any day over boo.
 If the bow is 1 3/8" wide and you shape the boo to fit, the boo should have knife edges after you thin to 1/8" at the crown.

Build it the way it is. I have built over 100   Bamboo backed, R/D and have played with precutting the shape of the bamboo and sanding to 1/16 thick even all the way up the limb. I have also jointed the bamboo flat at 1 1/2 wide the cut the bamboo out so at the tips it 1/4+ thick. Ive made them out of every wood you can name and them some. After years of research, I have found (cronagraphing) it does not matter. I joint all mine flat and go with. I build bows with Curt Brisky from brisky bows and we play around with ALOT of things! Build it!!

I always prep bamboo the same way.
Flatten the belly side (non rind side) Many ways to accomplish this, jointer, sander, hand tools.

Cut to just outside of profile and get to profile with a sharp low angle plane set to take fine shavings (Careful to avoid bamboo splinters!!!) and a rasp or sander in the handle area.

Reduce thickness to 1/8" at the center of the handle area and no more than 1/16" at the tips (measured at the crown, not the edges) I use a low angle block plane and a toothing plane. I feel it gives me more control than a belt sander, but that's me; plus once I'm at the thickness I want, my surface is already prepped!

Ok thanks for all the advice guys. I was thinking tho, would if I decrowned it to thin it down  and then backed it with rawhide? I have heard that suggested before.

I would save the rawhide for another project.
Maybe just see what you can do with it as is. Just don't go too fast so as not to have a hinge or fret before you can catch it.
Ron

Ok I'll see what I can do