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Main Boards => The Bowyer's Bench => Topic started by: rich k on May 25, 2015, 07:16:00 PM

Title: .040 vs .050 glass question
Post by: rich k on May 25, 2015, 07:16:00 PM

Somewhere along the way I learned to use .040 glass on recurves and .050 glass on longbows in the 45 - 55 # range. My question:
If I use .040 glass instead of .050 glass on a longbow and increase the bamboo core .020 to maintain the same limb thickness, what happens?
Is it the overall thickness of the stack or the thickness of the glass that determines the eventual draw weight?
Thanks for any wisdom

Title: Re: .040 vs .050 glass question
Post by: jsweka on May 25, 2015, 10:13:00 PM

You will have to increase your stack more than 0.020 because the thickness of the glass increases  bow weight proportionately more than the thickness of wood/bamboo.  How much?---I'm not totally sure as I've had different results and it probably depends on the design of the bow as well.

My suggestion would be to increase your bamboo core by 0.030, but that's just a guess and others might give you better advice.

Title: Re: .040 vs .050 glass question
Post by: BigJim on May 25, 2015, 10:42:00 PM

In my designs, I generally figure .002 per lb for glass and .003 per lb on wood/boo. That is with longbows.

I'm sure it varies some.

bigjim

Title: Re: .040 vs .050 glass question
Post by: rich k on May 26, 2015, 11:52:00 AM

Thanks to you both for the quick responses.