putting glass between lams?

[Longtoke]

I noticed one of my bows has a layer of glass in the middle of the lams.  what would the pros and cons of this approach be?  Has anyone else tried it?

[Crooked Stic]

Prolly core tuff. They used to use it to stabilize. There is also uniweft (a woven glass for that also.

[B-JS]

Pro: nice Colour accent, maybe a Bit torsional stability
Con: adds weight to the limb

[Kirkll]

The lightest weight glass product you can use for torsional stability in the core is Stable Core. its only .015 thick. Seems to work best right under the glass on back side of the limb though... If its dead center of the core it's pretty much a cosmetic  racing stripe.

A thin twill or bias weave carbon works better for stability. For a rock solid light weight recurve i've used .015 twill over stable core on the back and got incredible torsional strength in a 30# radical recurve limb. It felt as stiff as a 60# limb torsionally.   Kirk

[Camp Creek]

I don't see the point in that from a mechanical standpoint at all..  Fiberglass is denser than wood and the only point in adding that mass to the limbs is to provide strength.  The bending stresses are at a minimum in the center of the limb, so putting it there is pointless, and putting it at the back or belly would give the same torsional benefit.

[Longtoke]

It has me scratching my head. The bow in question is a toelke pika. Another member and I were talking about them and he says his doesn’t have it. Mine does though and looking at their website it looks like most of them do. And yes it is right in the middle, like it is in line with the riser fade.

[evgb127]

Here’s a good article on the subject that might shed some light or start a debate…

https://sunsethilllongbowsandleather.blogspot.com/2024/05/the-core-glasswhy-secrecy.html?m=1

[Kirkll]

Here’s a good article on the subject that might shed some light or start a debate…

https://sunsethilllongbowsandleather.blogspot.com/2024/05/the-core-glasswhy-secrecy.html?m=1

After reading that article about the only thing I agree with is how it could help a short riser block transition into the fades stronger without extending the fades, and possibly eliminate the need for a tip wedge in some cases.

When you have a bow with glass backing, belly and back the same thickness. The neutral plane will be dead center of the core. Heavier glass on the back than the belly will shift the neutral plane .  Adding a piece of glass to the core doesn’t change that… it’s nothing but a heavy racing stripe, and unless you are using a woven glass product, it does nothing for torsional stability. Even using a bias weave carbon in the core only has minimal effect on stability. The belly and back glass or carbon  is what controls that stability.   IMO.