tech input

[kennym]

Hey guys, has anyone built a couple bows -

 Same stack but .050 glass on one and .040 on the other?

Just wondering what different thick glass does to the weight,performance, etc.

All input welcome!    

Thanks!

[matts2]

interesting.  That will answer a lot of questions.

[Bowjunkie]

It depends. There are many factors, one of the biggest is... what kind of bow you're talking about. When you consider the stack heights of an average recurve vs. a longbow, and the "percentage of change" that will occur to the overall thickness in each of them by adding .020 glass... that change is going to have a greater effect on the recurve than it will the longbow simply because you will have increased the overall thickness by a much greater percentage.

Same thing when changing glass thickness, for instance, in a 40 lb longbow vs. a much deeper-cored, but otherwise identical 80 pound longbow.... a .020" addition is going to be a "percentage of change" relevant to each as an individual... not a straight (X) number of pounds across the board.

I have it in my notes somewhere how such things changed my bows' weights, but unless you make yours exactly like mine, same design, draw weight, overall length, riser length, etc, I doubt my numbers would do you much good. It would be ballpark at best.

The best thing to do IMO is to make two identical bows in your style, same woods, same everything... except put .040 glass in one, and .050 glass in the other, and see what you come up with. Then you'll know for sure.

[Apex Predator]

Instead of the 5# gain I expected, I got one 20# higher in weight.  This was a pronounced R/D longbow that normally would gain 2.5# for every .010 of stack increase.

[kennym]

Sorry, R/D longbow(shortbow? 58")

Marty, that is sorta what I was thinkin, but didn't know if glass thickness would matter that much. I was guessing a few pounds. Thanks for that info!

Any other takers?

[kennym]

Sorry, R/D longbow(shortbow? 58")

Marty, that is sorta what I was thinkin, but didn't know if glass thickness would matter that much. I was guessing a few pounds. Thanks for that info!

Any other takers?

[Roy from Pa]

I choose not to mess with glass bows. I know they shoot awesome, and they can be dialed in, but I do not consider them to be real traditional bows.  

Just my opinion guys for what I like to build. I love wood bows, and love boo for backing. Sitting here grinning too. Cause I'll bet I got a few glass bowyers nuts quivering:)
LMAO.. Just do yer thing guys.. Long as there are no wheels, I am cool with it.

[Sixby]

I found out something else that is very interesting but I am sure most of you know it. If you are using mixed glass and lay up one limb with the thicker glass on the belly by accident, the limb with the glass on the belly that is thickest will be way more poundage than the limb with the heavy glass on the back of the limb. Even though both limbs have exactly the same percentage of glass and same stack exactly.I am talking like 10 lbs more weight. Soooooooooooo If you want a real high performance limb and are building in a relatively light weight you might just experiment with using the heavier glass on the belly instead of the back. I would not try it with a heavy limb cause you might break the back of the limb .

God bless you all, Steve

[Sixby]

Roy to each his own, You need to walk instead or riding in a car or pickup though. LOL Oh and that electricity. Whale oil lamps work. Now you are saying any bow with glass is not traditional? I think you might be getting a bit elitist.Just a teeny bit. However Bro. Coffee is still coffee and I sure will share a cup. As long as you think I am good enough.

God bless you, Steve

[Bowjunkie]

Yeah, Ol' Roy is opposed to fiberglass in bows(which is as 'trad' as ANYthing) but not opposed to using modern epoxies, finishes, tools, digital cameras, the computer and the internet, etc. to make his bamboo backed bows. LOL

What I can't understand is why he avoids selfbows...

Wait.... could it be that he himself is infected by the fiberglass mentality? That would explain his detachment from the realm of selfbows AND his propensity toward bamboo-backed bows(whose 'cookie cutter' construction materials, methods, and jigs, etc. are not so unlike those used in glass bow construction), yet he shows a strong dislike for glass bows?

Hmmmm, that's strange  

[Bowjunkie]

Sixby, yepper on the belly thing.

Related..... That's why you can 'trap' the limbs on a glass bow by narrowing the width of the back, lowering mass limb weight without losing as much limb strength as you would by trappin' it the other way.

[matts2]

I asked this question a few months ago and most people told me the weight is determined on the total stack and not the thickness of the glass.  But now I am reading that thicker glass with the same overall (glass and core) thickness will give you a different weight??