I second What Will said. I would add another possible option. Bamboo back Osage is an excellent option and great performer. If you’ve got boo strip long enough and can get your strip taper down then glue up with ea40 or similar glue is a much faster option. Sinew is great stuff do t get me wrong and I do a lot of it but boo backed Osage is really good. I’m sure others will chime in on how good of a combination it is. A very small amount of boo strip goes a long way too. Depending on how much weight you are trying to recover with sinew it may be out of reach. Not the case with boo backing. Not exactly primitive if that’s what your aim is with this bow build but I’m throwing it out there as an option. Even the last couple sinew backed yew bows I did recently with tb3 glue worked out very well but still needed a couple months to really dry. Just another thought that for those who followed that bow build little while ago, the tb3 variant did t dry any faster really if you recall and in my opinion may have taken little longer actually. My theory is that perhaps the waterproofing aspect of the tb3 glue prevented it from drying through the top layer and dried more through the wood of the bow which would naturally take longer. I’ve got two yew builds on the go right now and they have just now settled in to their weight loss limit and go up and down in weight depending on atmospheric mc. The other thing to consider is the dry time and your timeline for the build. If rushed in the build with sinew backing you will just add mass and no added draw weight if bending and tilling too soon. Time is your friend. The boo backing with ea 40 is overnight from glue up if direction on can are followed. There’s a lot of guys on here making really nice boo backed bows that can get you some taper dimensions and such. For reference I did a boo backed bow not long ago and I went from Week bow under 30lbs, prepping the slat taper, glue up, quick retiller and less then two days to shooting bow. The other option is as you stated a belly lam. If bow is week but tiller is looking good then getting a nice dense peice of ironwood or other contrasting suitable belly lam will do the trick too. It also adds more draw weight then expected. Best of luck. Keep us posted on what you end up doing.
