Glass Ratios & Questions

[JSMOFFITT03]

Hey guys, have a few questions regarding glass ratio calculations...

As a rule of thumb I know you only want roughly 20-25% of your total stack to be glass.  What happens to that ratio when you throw core-tuff or uni-weft to the internal(core) of your stack?


Moving on,  What is the preference performance wise for using lets say .04/.03 back/belly over a .04/.04 back/belly combo?  Those sizes are not necessarily my stack choices but just as a reference for using differnt thicknesses of glass for you back and belly.  Are there any advantages for doing this or it just personal preference?

Last but not least,  how does internal core-tuff or uni-weft effect the outcoming weight in calculating your stack? Lets say per your design, you want to reach around 50#, typically your total stack is .36 glass and core wood combined .  Will your overall stack thickness have to decrease when adding the composite type materials to your core?  What about the 20-25% gass ratio?  would adding internal composits effect the ratios?

Wow,  finally go that out, my mind was going crazey trying to get that out....

Look forward to the responses,  thanks agian in advance....

[JamesV]

It was recomended to me to use .040 back and .050 belly. Thought being that glass is stronger in tention than compression. Don't know about your other questions.

[JSMOFFITT03]

Thanks JamesV,  for some reason i thought you wanted to put heavier glass on the back...  something about not wanting the belly to over power the back....  

I probably have it backwards...  thanks agian

[Dmaxshawn]

I'm in the process of glueing one up just like you speak of and have the same worries.  So I asked Elmomt and he told me to keep my same thickness.  I also asked the benches expert KennyM and I don't remember exactly what he said. But we both seem to agree that it will make a heavier bow.  

I'm going to drop .005 from total stack and roll with it.  Or either wait and see what's said here.  

Shawn

[kennym]

I did build one with .035 on belly and .045 on back, no diff noticed in speed, think I'll go with thicker on belly next time.

This one, which he loaned to a bud who lost his bow off the truck top, this bud killed 10 deer and pigs with it in about 10 months!!

http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=004038

I think Shawn is about right on the .005" less, but thats a guess!

[BWD]

Originally posted by kennym:
This one, which he loaned to a bud who lost his bow off the truck top, this bud killed 10 deer and pigs with it in about 10 months!!  

Yes he did, and says he is only pulling 38#s on it, at his draw length. Don't think it's a loan anymore...don't see Marty ever getting it back.     :D

[Crooked Stic]

I cant think of a good reason to have thicker glass on the belly. I would at least keep the same thickness back and belly for durability.
Glass being better in tension is the reason you would use 04/.03 for performance. i personaly think you would be ok in lighter bows .04/.03. From a bowyer stand point you want more durable.

[JSMOFFITT03]

Thanks guys, great info here!!!

Kenny as always, thats a beautiful bow you built!!!!

Crooked stic,  I second that on durability....