1st Lam Recurve Build - no glass?

[Wildfire]

I built a hickory self-bow a few years back and have been very happy with it.  Some friends have enjoyed coming over and shooting it with me so much, they wanted to build some bows of their own with me.  We decided to try laminate recurves.

So...we have 6'2" x 2" staves currently at .15 thickness in hickory, cherry, maple, black locust, and 3.5' x 1&3/4" osage billets (cut the osage tree down ourselves over a year ago).  In all we have enough to make at least 6 bows in different wood combinations.

My first question is can we make the composites without using glass?  If so, with the lack of glass what should our thickness be for our final wood stack for a 50-60# draw at 29" of a bow with overall wood length before recurve at around 6'?  I think we are going to try some with 3 lams and others with 4.  Should each lam thickness be about the same?  And also, if you aren't doing glass, do you need to cure the bow in a hot box?  I have heard epoxy is better if cured without heat.

My plan for one of my bows is Hickory back, then cherry, then maple, then osage belly.  Probably going to have a bunch more questions as we go... Also hoping to do a build-along, maybe for each bow.

[Black Mockingbird]

So you've built one bow(self bow)...and you want to build a tri or quad lam all wood laminate recurve...good luck...its not an easy build...I've built lots of bows and it still pushes my skills...BUT...yeah it can be done..here's one I recently finished up

 http://www.primitivearcher.com/smf/index.php/topic,42101.0.html

To answer your questions right it wood take pages to do it correctly...you can start with set thicknesses on all your lams,but you'll still have to tiller it like any other wood bow...3 lams is enough(n maybe even too much for your skill level) but if you do I'd go hickory backing with a 1/8"-1/16" taper...a maple core with same taper as the hickory...and an osage belly that tapers 3/8" from the fades to 1/4" at the ends...the thickness of your osage will be parallel thru the handle section,and that thickness can vary depending on how you want to do your handle...i recurve the osage before glue up,and the backer and core are so thin that they will conform to the recurve shape of the osage at glue up...GOOD LUCK!!! Your gonna need it    use epoxy and adhere to the specific instructions of whatever glue you use

[Black Mockingbird]

Oh BTW...where at in Ohio are you? I'm only a couple miles from the border...maybe I'm close enough to help ya out firsthand? You'll prob need it attempting something like that honestly..

[LittleBen]

In my experience the toughest part is getting good clean tapers on the lams. I find that tillering tends to be very minimal if the taper is carefully chosen.

If you can make it through the tapering and glue up I think you're in the clear.

[Wildfire]

Thanks guys.
My friends and I are all accomplished woodworkers.  One works for a wood sign company, one is a luthier who makes acoustic guitars that sell for $5000+ and I have built furniture and martial arts weapons for a few years.  Between us I am confident that we can get a few good bows out of 6 or more tries.  The issue we are having is knowing the details of what to do, the execution isn't what I'm concerned about.

I want to taper the cores and leave the belly and back parallel so we have as much wood to work with for tillering.  In future bows (after we make one or two) we may try tapering the back or belly.

For now I just need to know how thick each lam should be, how much to taper (for both a 4 lam and 3 lam), and where to start those tapers.

Here are the lam plans we have for the first bows:
Hickory (back)
Cherry
Maple
Osage (belly)

Hickory (back)
Black Locust
Maple  (belly)

Hickory (back)
Black Locust
Maple
Osage (belly)

Thanks for your advice!

[LittleBen]

I use this as a rough starting point .... for every .100" of limb thickness at the but end of the lams, I put in roughly .001" - .0015" taper .... so for a limb thickness of .500" I'd use a taper of maybe .005"-.007" or so ... that'll get you close. This also assumes you're makign fairly narrow limbed bows and nopt 2.75" wide pyramid bows or something.

My most recent was 60"ttt 1.5" wide, .420" thickness, with a total taper of ~.005" and it basically was already tillered when it came off the form.

If it we're me I'd recommend tapering all of the lams ... I think it makes the tillering easier, and ends you with a nicer product ... nice even lams that are proportional all the way to the tips ... You're probably not going to get all the taper you need just in the core, so you're gonna end up tapering the belly during tillering either way ... I find it easier to do before glue up than after.

To address your questions specifically, I taper the lams in 36" sections, then slpice then together. I think some people keep them parallel until the end of the riser to make the glue up easier.

I don;'t know what thickness you will need unfortunately ... but I can say this ... with lam bows, if they come in under weight, you can just glue on another thin belly lam.

[Wildfire]

Thanks LittleBen.

Planning on making 1|1/3" and 2" bows.  Overall wood length will be 64"

What would you suggest my wood stack thickness be?  About .420"?  

I want to start the taper at the end of the riser.  How much taper should I put on each lam?  .001" per inch of length?

[LittleBen]

The two hickory backed osage bows can be similar in stack becasue the core is not going to affect the draw weight very much, the maple will come out a lighter weight at the same stack because maple is less stiff than osage.

.420 will not yield the draw weight you want in a 1 1/3" wide bow .... I assume you're going to go 2" wide with the maple bow only.

TBB vol. 4 has a section on laminated wood bows, Mike Westvang described using a bamboo backing, a tapered osage core and a parallel osage belly. The specs for the bamboo taper are not specified but I would guess based on the description of the processing method of the bamboo that it is probably around 1/8" thick tapering to about 1/16" thick. That gives a taper of roughly .002"/inch.

Here are the specs for the lams:

Bamboo Back - .125" thick .002"/" taper
Osage core - .190" thick .002"/" taper
Osage belly - .180" thick parallel

Total stack ~.500" thick. That was for a 64" bow with an 18" powerlam (riser) between the bamboo mack and the osage core, and having 12" tip wedges (.070" thick tapering to paper thin). Lastly his bow was a r/d design. I think it was around your target weight.

I'd recommend going like this:

Hickory back: .125" thick, .001"/" taper
Core #1:      .125" thick, .001"/" taper
Core #2:      .125" thick, .001"/" taper
Osage Belly:  .125" thick, .001"/" taper

This will definately get you in the ballpark, but with such thin belly lam, you will not have alot of material to work with for tillering ... you'll be at only .093" thick at the limb tips. The other downside is you have to taper 4 pairs of laminations.

You could also do something like this:

Hickory back: .125" thick, parallel
Core #1:      .125" thick, .002"/" taper
Core #2:      .125" thick, .002"/" taper
Osage Belly:  .125" thick, parallel

Theres a million variations.

For the hickory backed maple I'd probably taper the core lam at .002"/" and taper the backing and belly lam each .001"/".
.125" backing, .190 core, and maybe a .200 belly. I'm just guessing to be honest.

Build one and see how it turns out, then it'll be easier to make a decision on how to make the next one to hone in on what you really want.

[Wildfire]

Thanks!  Thats exactly the kind of info I was after.  Huge help!