Help with first bow

[Yourpaldan]

Hi folks,

Just ordered some wood from Boisebowsandarrows.com.  I've been stalking tradgang for a while now (first post).  I'm a woodworker and furniture maker, but this will be my first bow.  yay!

I've ordered some Argentine Osage (1.5" x 3/8" x 72) and bamboo for backing.  Question:  How will i know if i need a core lamination?  Can i bend the osage stave and get a feel for how much flex it has?  I'm not too fussy about poundage of the bow... i guess around 45#+, but I'd rather just feel it out as i tiller, and go for what feels right for me.  I have lots of walnut for a pistol grip riser, and i can make some tapered, straight grain walnut laminations to add to the core if need be.  But how do i know if i'll need it?  3/8" Osage seems thin to me. Also, should i steam bend all the lams before glue up?

Also, it seems to me that just using glue to hold lamination in curve, you're forcing the wood grain in a direction it doesn't want to go.  Then the glue is storing more energy then the wood.  Why not steam bend it first?  Then the natural rest state for the grain will be in recurve. Otherwise the grain is fighting the glue even when unstrung.

btw, I'm shooting for a smaller hunting bow around 60" long, straight from the riser, with some reflex in the tips.  And i have some beautiful Australian Lacewood that I may add to the handle and tips if the bow doesn't break before i get to that point.  This wood looks like a polished gemstone after you sand and finish it.

p.s.  You guys have so much knowledge and experience around here!  Its been so nice just to look through everyone's builds and soak up all this free info!  I like learning from other people's experience, and some mistakes.  But i guess it's time to make my own mistakes.

[BMorv]

Welcome to the Gang.  If your osage is only .375" thick you are better off planning a tri lam with a walnut core.  You won't have enough material to taper then tiller to get you to a hunting weight bow.  Most start with a thickness of at least .5" when planning a bamboo backed laminate. 
Steaming adds a lot of complexity to your project and it's not needed.  You can glue in reflex or deflex in basically any shape you can think of (within the bending limits of the wood).  The way I look at it, the glue is holding some of the reflex/deflex forces so it leaves more potential for the wood.  There's only so much stress each fiber can hold before it breaks. 
What's your draw length?  60" is really short for your 1st try.  You won't have much working limb to distribute forces, so you will be working with highly stressed wood which calls for a near perfect tiller.  Unless your draw is like 22".   

[Yourpaldan]

Thanks... That definitely helps.  So ill go longer... (I draw to 29").  And I better get started on those walnut lams while I'm waiting on delivery.

Another stupid question re: basic phycs of archery... 
If a bow is under tension at brace, then that pre-load is stored energy which never gets transferred to the arrow.  What if I shape a bow so it has almost no tension at brace.  That is, the bowstring is just pulled tight enough to stay on.  Instead if i tiller the limbs stiffer, so that i still reach my target weight at full draw.  Then all of the energy in the limbs would used up in casting the arrow.  I guess it would stack weirdly?  But in theory it seems more efficient to me from a mechanical perspective. Does this make any sense?

Now I know that if this were a good idea, then bowyers would already have tried it.  So why doesn't it work?

[BMorv]

29" oooo, definitely go longer, like 68-70".

I would suggest reading bowyer's bible 1, performance section.  String tension is proportional to early draw weight.  The area under the force/draw curve is the amount of work going into your arrow.  That area is larger when you have higher early draw weight numbers (all else being equal).  Most all high performance bows have high string tension.
Try a test for yourself.  Hold a rubber band at very loose tension and pull back a measured distance and shoot a projectile.  Then put that rubber band in tension between your fingers and then pull back the same amount and release the same projectile.  Which one shoots faster/farther?

   

[Yourpaldan]

Thanks bmorv... I really need ta get that book!

Anybody use clay to model your grip shape?
Was thinking I could cut a riser shape in clay, then grab it tight and squeeze to shape it to my finger contours.
That way I can use it as a guide in carving out the real riser that's fit to my hand?


Unrelated rant:
Its funny... I was thinking how there's a natural instinct for people to look at a thing and think "I can improve on that.  I can design it to be faster, lighter, better.  I can see it from an original perspective no one ever thought of before."
But the bow has been in use for... what, 50,000 years? By nearly every culture in history?  Its the result of a steady evolution.  Every idea has been tried probably...If ideas work, they stick around, and get better, otherwise they end up in the fire pit.  So using natural materials, the only way to improve a bow is to think of something that a millions of bowyers in human history all missed. 

Modern materials kinda change the whole paradigm though. So I see 2 ways of looking at it.  1) you can use natural materials and make a bow that  represents 50,000 years of human refinements, and directly connects us to our ancestors.  Or 2) use modern synthetic materials to make the most efficient bow possible, maybe even hitting upon a new innovation, but beginning a new era with a respectful nod to the past.

[Yourpaldan]

Traditional bowyers bible... Free 30 day trial with kindle unlimited.  All 4 volumes free, if I read fast enough.
Decided to make a couple board bows first as practice before I start on the osage.  I'm picking up some maple and oak from home depot, and try out a couple designs. 
Ill start a build along thread here next week...  with the practice board bows and the final BBO.

[Exiled_Archer]

I would bet you would end up with some crazy hand shock ifthere wereno energy stored in the limbs.
 
And like bmorv showed with the rubber band example, you wouldn't have any energy pushing that arrow except for at the release.

And that board bow build is a good idea. I like board bows. They're easy to find, and help teach a lot about grain importance.

Also, a well made board bow will more than outperform a poorly made composite/glass bow.

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[Roy from Pa]

You will prolly want to hang onto those Traditional bowyers bible books.

[Exiled_Archer]

I'll second that. I reference those things a lot. You could go ahead and read through them, but unless your memory is that of a computer, you'll need more time with them

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[Yourpaldan]

1st bow!
Maple board from Home Depot.
I found 1 with good grain

[Yourpaldan]

66", pyramid design from 2" limbs to 1/2".  It took 1.5" of set.  And came to 15# @ 28".   Oops!
By the time it was tillered nicely it was only 15 lbs!

Rather than trash it, ill use it as a chance to try some new techniques.
Ill reflex the tips, rawhide back and shorten as much as I can.
How much length should I remove from the limb tips? 
Is 3" each side too much?

I don't mind if it breaks, but I wanna use it to learn as much as I can, and push the envelope a little.

[styksnstryngs]

About the clay grip idea, that might be comfortable but not conducive to accurate shooting. The idea is to have no torque, and molded grips induce too much.

[Wolftrail]

"66", pyramid design from 2" limbs to 1/2".  It took 1.5" of set.  And came to 15# @ 28".   Oops!
By the time it was tillered nicely it was only 15 lbs!"

Give that  bow to a kid.   As far as lumber yard Maple goes it bends like wet spaghetti with a heat gun even after laminated, just dont over heat or the glue way give.