well my curiosty got the best of me.  I just couldn't help myself.   .  it had been in the back of my mind for sometime.  The straw that broke the back was I got Jaap video.  He commented that he had made glass bows using the rope and wedge......I got a strip of 0.30 glass coming, I got a 9/16" osage slat 58" long, I got wedges ground out.   I'm gonna make a Indian "D" bow with a glass back, wood belly.  

Dang I'm galde Tim Baker ain't around.  He be sending me a mail bomb.  56" ntn, glass back, osge belly, bendy handle Indian style circular tiller.  

got any thoughts (be nice now, it is a curiosity thing [they would have used it if they had it    ] )

rusty

as i recall the first glass backed bows your jsut glass backed.  didn't St charles build some, maybe I remember Strunk build some???? any thoughts

rusty

I have built 4 bbo Indian D bows.  they shot like a lighting bolt

rusty

s I cover it with a snake skin and call if action sinew  

rusty

Rusty,
We've actually talked about just backing our bows and not putting anything on the belly as one of the experiments we want to make.  Never have gotten around to it but it's an idea with merit.  As long as you use osage or some other relatively bomb-proof material in the belly it ought to work just fine.  Now, what you really ought to do is exchange that .030 glass for .030 carbon, reduce the 9/16ths slat to about 1/2 or maybe even 7/16ths and then you'd be smokin!  Can't wait to hear how this one turns out.  One suggestion is that you should probably double up on the glass across the back of the grip area on that bendy-handled bow.  It doesn't have a true back since that slat will have grain violations.
John

If I remember right, the first bows Frank Eicholz did for Howard Hill were finished bows with a very thin piece of 'glass laminated to the back, clamped down over nodes and all.


Ought to work just fine, Rusty.  I would keep the glass thin enough to avoid adding much in the way of weight.

Bro Randy made one like that Rusty but only because his eastern red cedar wouldn't quit lifting a splinter. He no sooner glue one down and another would pop up so he just planned the back and using smooth on put on an .030 (if memory serves me) strip of clear glass. It worked ok.Sure was a pretty thing. Here's a pic (gosh he looks so young in this pic ha ha)

http://groups.msn.com/ferretsarcherywebpage/picofbowswevemade.msnw?action=ShowPhoto&PhotoID=179

I saw a few bows Jim Fetrow had that were glass backed.  Most had yew bellies.  I think a better experiment would be to build a sinew backed pony bow with a clear glass belly.  I won't take much set and it would be hard to tell that it had glass on the belly.

I've built a number of fiberglass laminated bows (many all-wood laminated bows too) using rope & wedges with a 2x4 form.  It works pretty well.

Jason

Jason how in the heck would you tiller it with glass on the belly? If you tillered it first and then tried to glue on the glass you'd have a heck of a time getting a good glue line.

You can tiller them by laying out a pyramid style bow.  Or you can pre-taper the osage slat based upon limb thickness tapers on previous osage bows you've done before.  Or you can tiller by adding sinew here and there (if you're sinew backing it).

One thing I've noticed is that the thickness tapers or at least limb thickness ratios on glass laminated bows and all-wood bows aren't too much different.  You want the tip about 1/4 as strong as the innermost part of the limb.  You can get there using a pyramid width taper (1.5" to 3/8") or by thickness taper (tip is 5/8 as thick as the inner limb) or a combination (tip is 1/2 as wide and 3/4 as thick as the inner limb) to get a circular tiller.  That strip of glass on the belly and back doesn't change things much, the 2xwide = 2xstiff, 2xthick = 8xstiff formula still works.

At least that's been my experience (glass laminated and all-wood) anyway.

Jason

now that is a lot to think about.   for the first time I just gonna tiller the belly

rusty

Rusty,

It would be interesting to hear what you tip and fade/dip measurements are on your pony/sliver bows.  I would like to know if they still fit into my experiences.

Jason

Jason, I'll take some good measurments but I can tell that 54" ntn 1" wide midbow, 3/4" tip is just about 7/16 thick (given room for the variuous densities)
rusty

that is for a 45-50#draw at 26".  I don't think it will miss that 7/16 more than a 1/32" but I will get ya some good numbers.  Of course crown can make some difference, root end is ususally a bit thicker, and if it tension wood it can get pretty thin     if it is compression wood I've had it go pretty thick

rusty

Rusty,
I've made 6 glass-backed wood-bellied bows. (bought six pieces of glass)  All were flat-bow style in the 62" range though. I used bamboo flooring as the belly on a couple of them and they were kind of dud bows.  The rest were hickory / osage and they turned out well.  I used Urac to glue the glass on which I learned later is a no no,  but to my knowlege they are still holding together.
I've got several old longbows that are baked with glass only.

Wingnutty and I are gonna get together next Tuesday and put the bow together.  Think I will take it as a back up for the AZ javie hunt.  sinew bow for sunny and dry, action sinew for wet and damp  

I try to take some pics

rusty

wet & damp?...I thought we were hunting in the desert...desert=hot and dry don't it?

Mickey,

Rusty and I have brocken many a drought in our hunting adventures.  Twoi years ago I got wet in my tent because it downpoured in the middle of the night in the desert.

Mike

Yep they said it had been that dry in 10 yrs....till wingnut and I got there.  Don't ya know sinew bows draw water   .  All ya gotta do to break a 10 yr drought is take a sinew bow hunting and sinew bow for back up

rusty

Wingnut and I decided to start the bow a 1&3/8" wide.  we can trim from there for a 55 to 60#er at 26" (natural draw).  think I'll make it 58" tip to tip and circular tiller it.

Wingnut thought about leaving the mid bow parrelell.  I don't know it sure is easier to hit the tiller with the limbs tapered from mid bow to the nocks.  Ya don't have to taper the belly near as much?????? hmmm don't know.

rusty