Well I'm I'm putting the finishing touchs on my wall art glass bow( read the bubbles thread, I'm afraid to pull it back). Next I'm planing on a boo backed hickory/Osage lam bow. I'll be using the travaling caul pattern but have a few questions.
1. Glue- I have some smooth on left over from my last bow. I know urac is recommended for all wood lam bows but will the smooth on work as long as I have good clean tight glue joints. I know that with boo you rake the with a saw blade for glue prep.... Same procedure with smooth on?
2. Stack thickness- I'm looking to achieve approx 55# @ 28" 62" ntn. With a glass lam it seems around.385" total thickness is close. Atleast that's what my research tells me...
Would that be the same for boo?
Any recomendations?
Thanks
Go ahead and use the smooth on. I quit using urac for all wood bows as I have the smooth on and I feel it has a longer pot life than urac. Gives me more time to get things lined up and clamped down. I just sand the back of the bamboo with a 36 grit belt on a belt sander.
As you are making an all wood bow, I would start a little thicker with the hickory/osage stack-up. It depends on your limb design. You can always sand some wood off to bring the weight down. It's harder to add wood!!!?!?!?
Smooth On will work fine. Make your gluing surfaces flat, but not smooth. Too smooth and the joint is starved of glue when pressed together. Think about the surface of a ground lam that you would buy for a glass bow. Make it similar with a toothing plane blade, bandsaw blade, corner edge of a file, coarse sandpaper, or whatever.
.385 would get you close, not counting the bamboo. It would depend of course on your profiles, widths, etc. The last tri-lam I made was boo/osage/osage.
The boo was made as thin as I could make it... approximately 1/8" at the center and 1/16" at the tips.
The center lam of osage was 3/16 parallel from dip to dip, then tapered from each of them to the tips.
The belly lam of osage was 1/4 parallel.... leaving wood for removal during tillering if necessary.
The bow is r/d in design, 58" ntn, 1 1/8" wide and ended up being 57# @ 28".
I could go out and measure the exact finished dimensions on this bow if it would help, but basically you just want to set it up so that you're not scraping/sanding into the first glue joint during tillering.
thanks guys.... exactly the kind of info i was after....
ill keep you posted..