multi-lam bow questions without the glass (of course)

[The Burnt Hill Archer]

i know ive seen guys do this on here before, a multi lam bow as in more than a tri-lam.

my idea is a hickory back and osage belly paralell lams, and tapered black walnut core lams. 68" ntn 1 3/8" wide down to 3/8"nocks, only slight reflex added at glue up. no deflex.  my question is, as far as total stack thickness goes, would anybody have some general idea where to start for a 55-60 lb bow? i know its kind of cheating, asking these kind of questions before actually trying things out, but materials and time (or the lack there of) is really limiting my options.

do you think i would be able to take an aprox. thicness of a glass bow, and copy the design? or does the glass really add that much more umpff. i would really like to make this type of bow, but would even more like to stay away from fiberglass.

if anybody has any experience with these, please chime in.

Phil

[Justin Snyder]

I think I would keep the center Osage and the walnut to around 1/16". The additional layer of Osage on the belly will give you 3/16 plus the backing which will be fairly close, depending on the density of the Osage. You might get away with a bit thicker on the 2 cores, but then you run into the possibility of having a thin belly lam which increases the likelyhood of problems. I have had thinner lams on the belly without a problem, but I don't like it. Justin

[The Burnt Hill Archer]

ok, so were talking about 3/8 thickness. that sounds about like my hickory backed osage r/d. this is what i was wondering. that'll give me a good place to start. thanks! also if i remember right, dont you use just regular rubber bands to do your glue ups? have you got a picture of that set-up?

[Justin Snyder]

I meant to tell you to use a little thicker lam on the belly so you have a little room for tiller. You wont need much, but it is hard to add more later.
Yes, I just use 1/4" rubber bands from the office supply. Here is the link you are looking for. http://www.primitivearcher.com/smf/index.php/topic,1978.0.html

[Ryano]

Go to your local bike shop and ask them to save you there old inner tubes. Works better than anything else I've seen and there free.
3/8" over all thickness at that length sounds quite thin to me but then again I've only made shorter tri-lams.

[The Burnt Hill Archer]

yup thats the one thanks.

Ryan, ive been using strips cut off of a tractor tire inner tube i found on the river, but its almost gone. ill have to give the bike thing a try. also, didnt your brother make a laminated reverse handle bow a while back? osage and bamboo if i remember right. do you recall the specs on that bow?

i was doing some adding up, and i think ill start out with about 7/16" or 1/2" and leave my belly lam 3/16". that will give me a little room to play. i can always trap it if i need to take more wood off. right now, i would rather come out too heavy than too light.

Phil

[The Burnt Hill Archer]

any thoughts???

[Gordon]

The only purpose I can think of to employ so many laminations is if you want to recurve the limbs. Otherwise it seems like a lot of trouble for little gain.

[The Burnt Hill Archer]

other than being able to combine different woods...both for looks and for the performance gains of the different woods.

[Ryano]

Phil, I don't have the specs on his bow but I made a couple a few months ago. This one is 58" ntn around 40#@28" bamboo backed maple core ipe belly.

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[radius]

hey Ryano!  what do you think of doing a buildalong of one of these great reverse handled bows?  That is something alot of guys would benefit from and thank you for. 

Scott