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Core Lamination???

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Wooden Spring:
OK, stupid newbie question... What is the purpose of a core lamination in a tri-lam bow?
If I've got plenty enough material for a hickory backed Ipe longbow, would a core lamination actually do anything?
(Incidentally, I only want about a 100# to 120# bow)

Furthermore, will this design work to produce a 100# bow?
Note that the bow arches from nock to center, there are no straight line cuts in the bow. I used to be an architect, so I shaped this like I would have drawn a pre-stressed beam. (holds more load) But I'm not sure how that would transfer over to bowmaking.
HOPEFULLY I can get the picture to post...

adb:
Your dimensions look perfect for a reasonably heavy bow. You 'only want' 100 - 120#? That's ambitious. Especially if this is your first heavy bow. Making a 100+# bow is not easy. Well... a good 100+# bow, anyway, with good cast and little set.
Yes, a core material is structural. With a tri-lam construction, you end up with 3 layers, and 2 glue planes. If done properly, the glue joints are stronger than the surrounding wood. Each glue joint creates 2 opposing forces at the joint of tension and compression. The core material is important. I use only strong hardwoods, like purpleheart, yew, osage, cherry or bloodwood. Some people think the core material doesn't matter, but that is not true. If you're making a FG bow it is true... the core does nothing more than hold the FG, and the FG does all the work.
Also, the tri-lam is a good looking bow IMHO, if the 3 woods used have nice contrast. I make a lot of tri-lams, especially for heavier bows. I use parallel lams, usually 1/4" thick for back and core, and then add belly wood depth to accomplish weight (usually with overall thickness of 1 - 1.25").

}|{opukc:
 This is just to reduce the overall physical weight. What I gave in size to the other theme will work well for that weight.
I have 3 lam warbow that is of similar size and pulling 136 # @ 32 " for 74"

http://www.primitivearcher.com/smf/index.php/topic,33227.msg438561.html#msg438561

With hickory/Ipe maybe you should start a little thicker and wider - 1 3/8" x 1 1/4"

Wooden Spring:
Thanks for your help adb... You're right about this being an ambitious project - I didn't know how ambitious of a project this would be until I got onto my third try - I'm not new to archery or woodworking, but I am new to putting those two hobbies together.

So far my first bow attempt suffered from a dramatic suicide... I had an Osage Orange belly that I didn't score deep enough to prepare for the BowGrip100 - I had tillered the thing beautifully, then when I finally got it to pull down to 32", an 8" piece of Osage snapped off and embedded itself into a nearby 2x4. The next bow that I put together was apparently with the wrong materials (1/8" hickory back, 1/4" Ipe core, 3/4" hickory belly), it tillered nice, but my 210 pound body and gravity's help couldn't pull it down past 30" with the extra long tillering string, so it sits in the corner of my shop now collecting dust... My third attempt got the materials right, but when I put it into the hot box to cure the BowGrip100, my hickory backing dried out and curled up away from my core wood leaving a gap....

SO... I've learned that I need to use a glue that I'm familiar with and have used for decades - Titebond 3. AND I need to use my materials a little different - in this case, a 1/4" thick hickory back, and an ipe belly. Maybe #4 will produce a shootable bow! So far this little adventure of mine has been nothing but a comedy of errors worthy of a Marx Brothers movie!

}|{opukc:
With hickory/Ipe maybe you should start a little thicker and wider then to reach final dimension - 1 3/8" x 1 1/4"

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