About Specific Gravity of Bow woods

[edy5dms]

This is a question in conjunction with one of my earlier questions “what are the desirable properties of a certain wood used for bow making”

The questions are:

What does “Specific gravity” of wood mean for a bowyer or how does it affect the process of selecting a certain wood to use on a bow?

What can you determine or understand about a certain wood by knowing its specific gravity value?

In which range of specific gravity values should the wood used for, especially Limb lamination should be?

How big a deal is Specific gravity of a wood?


Thank you in Advance for your replies.

[Pat B]

Again, are we talking glass bows or wood bows? Specific gravity determines wood density. Generally speaking(for wood bows) the higher the SG the better the wood for wood bow building. Compression and tensile strength makes a difference also. For glass bows there is very little to be concerned about because the glass takes all of the tension and compression stresses. The wood serves as a gluing surface but also as a decoration.  A strong wood with less SG, theoretically speaking, makes a better lam for glass bows because it has less physical weight. The lighter the physical weight the quicker the limbs will recover.
   For wood bows, a SG of over 50 is usually what you are looking for...but not all high SG woods are necessarily good for wood bows. Tensile and compression strengths and a proper design are more important IMO.     Pat

[onemississipp]

I believe he is talking about glass...In a glass bow the wood choice is not that critical....It isn't doing much work..

We'll lets rephrase that a bit, the wood in the limbs aren't doing much work.

Your riser wood should be a good strong wood...

Check this link..

 http://onemississipp.googlepages.com/bowwoods

[onemississipp]

and this one..

 http://www2.fpl.fs.fed.us/TechSheets/techmenu.html

[Apex Predator]

Great links!  Thanks onemississipp!

[onemississipp]

No problem Apex, thanks for all you contribute also!

[edy5dms]

Originally posted by Pat B:
Again, are we talking glass bows or wood bows? Specific gravity determines wood density. Generally speaking(for wood bows) the higher the SG the better the wood for wood bow building. Compression and tensile strength makes a difference also. For glass bows there is very little to be concerned about because the glass takes all of the tension and compression stresses. The wood serves as a gluing surface but also as a decoration.  A strong wood with less SG, theoretically speaking, makes a better lam for glass bows because it has less physical weight. The lighter the physical weight the quicker the limbs will recover.
   For wood bows, a SG of over 50 is usually what you are looking for...but not all high SG woods are necessarily good for wood bows. Tensile and compression strengths and a proper design are more important IMO.     Pat

Thanks for the answer pat and I'm looking to build a Glass bow but thought about building a few all wood bows to look in to the suitabilty of local woods on bow making, since all wood will give better understanding of capabilty of the wood used.

The final goal is the build a Glass bow both a long bow as well as a T/D recurve.

Thanks

[edy5dms]

Originally posted by onemississipp:
and this one..

  http://www2.fpl.fs.fed.us/TechSheets/techmenu.html  

Thanks a lot the two links looks pretty good I will look in to them closely. Thanks
again

[edy5dms]

Wow the links are awesome Onemississipp, Thanks a lot

[Roy Steele]

Boys this ain't brain surgery.What happened to just building bows.