i have built many boo back and belly bows,, my goal is to not sand any on the surface of the belly or back,, if your lams or core is tillered sufficiently,, there is no need to sand the surfaces,, the only sanding i do is on the edges of the bow and when i trap the bamboo .. to drop the poundage ,you can narrow up the bow and (or) trap the edges of the bamboo more.. James