I disagree with the naysayers. I've had swirly bows work out and straight grain wood snap. You can't alwayse tell.
Bamboo backing: I like to get my bamboo as unprocessed as possible. Saves money and steps that aren't terribly difficult even with hand tools. Once your blank is spliced and the seam and back flattened. I lay it on top of the bamboo strip and trace the outline. Let your pencil add a tad to the perimiter then saw just outside that. you'll get about an 1/16 to 1/8th in overhang.
I then saw the belly taper but stop short of where the riser will cut into the belly You'll cut that later. If you are going for deeper reflex deflex sand the belly enough to eliminate or at least serriously reduce the saw marks. This isn't necessary if you are steam bending the curve in but if you are going to cold bend and glue it then it might cause a problem.
I like a riser section to be 10 -11 inches long and cut on a VERRY gently curve where it meets the belly. Pluss I ad a 1/8" strip of contrasting wood. Makes the seam look nicer. An exact match and clean curve is hard to get between the curve and the riser block so that strip splits the difference and makes it look nicer.
I use a band saw to cut the perimiter first on the bamboo then cut the thickness down to about an 1/8" or slightly larger. tilt it at an angle so that you'll cut from both sides and crate a tiny crown down the middle. I use hand planes and or a belt sander locked in my vise to sand it flat.
Then I use hack saw blades to scratch up the belly of the bamboo and back of the bow blank. Mark center markes for you riser black and bow parts so they align when you glue them up.
I have interchangeable belly side up gluing blocks that fit to a straight bar of oak with center lines on them and the straight bar.
I use either unibond or weldwood plastic resin for gluing the boo to the blank but one could use tb3.
after gluing the boo and blank togeather I wrap with shrink wrap and use clapms to get it around my curved riser block, and the ends lifted and then wra the whole thing down with bike tire tubes. From there into the hot box at 140 for 4-5 hours.
pull it out when done clean the overhang up and glue drips etc then clamp it around your riser block and glue with tb3.
begin tillering and finishing out the bow. I don't do ANY bow bending untill the boo is glued own.
