R/D Tiller Discussion Continued

[Bayou Ben]

Very interesting.  I'm going to have to think this through.  My initial thought was that a tri-lam offers twice the amount of glue surface for holding the compression and tension forces so it must have more than a single lam, but it is also true that a thick lam holds higher forces than a thinner one.

I now wonder too which one would produce the better result?   

In your example I would say a 3/8" belly and 1/8" backing would benefit more since you are holding more force with the 3/8" thick piece. 
But in the case of (3) 1/6" lams vs a 3/8" and 1/8" lam, which would you say benefits more? 

[BowEd]

Good question and controversial.I'm in the thicker core group with 1 glue line.Most epoxy has a density more so than wood to consider too.Not sure if that's a facter though.

[willie]

I don't know what to make of the glue lines in the middle of the bow having a contribution to the performance. My understanding is that most of the work in a bow happens to some  degree on the back and more so on the belly surface.

 It does seem like there might be some benefit to applying the backing so that it stretches more at full draw.

As far as the belly goes, it seems that if it is prestretched to make the reflexed glue up, it can be drawn as much as it always would have to get to full draw, but if the the prestretched surface is removed, then unstretched or more normal  wood is being asked to get drawn further.

If I am using a high elastic modulus backing, (like Bamboo) with a dense, but medium elastic (in compression) wood, like shagbark or shellbark hickery, you would likewise bring the bow closer to finished dimensions to prevent crushing the belly and getting compression fractures.

[Stick Bender]

I wonder if the tri lam might be more durable in the sense if you develope  a crack in one lam it's probably going to stop at the glue line (particularly using smooth on ), of the other ? But that's a good point on the extra mass that Ed mentioned but might be a advantage something like hickory back maple core , osage belly etc ,lightening mass on the core and back . Marc St Louis has made a ton of speedy backed bows and like said ,he said in a another thread he has not seen any performance advantage with more lams ! I guess it is one of those controversy  topics but interesting !