Primitive Archer

Main Discussion Area => Bows => Topic started by: Tommy D on March 31, 2010, 03:30:22 pm

Title: Advantage of a Tri lam
Post by: Tommy D on March 31, 2010, 03:30:22 pm: What is the advantage of a tri-lam bow. Do you end up doing most of the tillering on the sides or is it just a question of making the belly wood a lot thicker than the backing and middle layer?
Title: Re: Advantage of a Tri lam
Post by: spinney on March 31, 2010, 04:45:32 pm: Tommy,

No major performance advantages.
Look real pretty though (Bamboo, purpleheart and lemonwood).

I think substituting heavy tropical wood centre lamination for a lighter wood (ash or sitka spruce) may yeild a performance advantage.

Andrew
Title: Re: Advantage of a Tri lam
Post by: Josh on March 31, 2010, 05:47:53 pm: The only advantage I can see is besides being aesthetically pleasing, you should be able to glue more bend into the limbs being that 3 thinner pieces bend better than 2 thicker pieces. JMO :)
Title: Re: Advantage of a Tri lam
Post by: medicinewheel on March 31, 2010, 06:27:59 pm: Tri-lam will store more energy than two-lam at a given reflex.
Title: Re: Advantage of a Tri lam
Post by: knightd on March 31, 2010, 06:35:37 pm: Quote from: medicinewheel on March 31, 2010, 06:27:59 pm
Tri-lam will store more energy than two-lam at a given reflex.

And be more stable.. ;)
Title: Re: Advantage of a Tri lam
Post by: markinengland on March 31, 2010, 06:56:47 pm: How/why would it store more energy? How would it need to be glued up to get the best out of it?

Dan Perry as in "Perry reflex" feels that a thick belly glued toa thinner backing stores energy better than thinnermaterialsglued together because the belly staveis undermore tension/compression when glued up thus "storing" up more energy. Inmy opinion there is a real possibility of a tri lam storing less energy!
Title: Re: Advantage of a Tri lam
Post by: jeff halfrack on March 31, 2010, 07:14:51 pm: Tommyd dose have a good question how do most guys tiller a tri lam? I'm curious as to what a typical lay up consists? I do my hbh with an 1/8 hickory back and my stave goes from 5/8 to 3/8 and I scrape to tiller and of course I taper sides just wondering? thanks for any input JEFFW
Title: Re: Advantage of a Tri lam
Post by: Lombard on March 31, 2010, 09:23:50 pm: I am curious about this, as Pat O'Sullivan had some beautiful bamboo back & belly bows, at the selfbow workshop that he and Ryan held last year. Still waiting for the composite workshop ;) Now that I have some bamboo, (thanks to Hillbilly61), I would like to try one.
Title: Re: Advantage of a Tri lam
Post by: Justin Snyder on March 31, 2010, 10:24:35 pm: You can decrease the overall mass by having a lighter weight core which give some performance improvement. You can glue a lot of reflex into the core and belly then pull some of the reflex out when gluing the backing on. This puts the belly under compression when the backing is relaxed.

Mark, I think if you asked Dan for clarification you would find that there are different parameters that effect the stress. If you glued the two pieces flat then glued them as a single piece to the backing it would store the same energy. If you glued it all to the form at once allowing the belly and core to slip they would definitely store less energy. If you glue them like mentioned above, they would store more.
Title: Re: Advantage of a Tri lam
Post by: Gordon on April 01, 2010, 03:15:00 am: A trilam is easier to glue into reflex because the core is thinner.