Using Info From "The Wood Database"

[arachnid]

Hi Guys.
"The Wood Database" (http://www.wood-database.com) has info regarding many kinds of wood.
Every wood has the categories- "Modulus of Rupture", "Crushing Strength" and "Elastic Modulus".

Can I use any of this info to determine if a wood is suitable as a bow wood (Beside spesific gravity)? (Let`s say, compering wood specs
with hickory specs)

Thanks
Dor

[JacksonCash]

I know specific gravity can give you some idea if a wood will work or not, not sure about the rest of it.

[wizardgoat]

This has been discussed on here many times before, and the general consensus is that the data base gives good info on wood species properties, but doesnt really give us the whole picture. We do something pretty specific with wood, so the best wood species to use are woods that have been proven. If you think you found a sleeper bow wood just post a question here, id bet someone has already used it.

[arachnid]

Ok then.
How about -chinaberry, brazilian rosewood (jacaranda), lebbek and sisso (indian rosewood)?

All of these woods grow next to my house, they all have sg above .60 and the other specs I mentioned above are pretty high.

So, what say you?

[Wooden Spring]

From what limited experience I have, the best way to know if a specific wood will make a bow is simply to make a bow out of it. 

[wizardgoat]

http://www.wood-database.com/wood-articles/bow-woods/

[wizardgoat]

Have always heard good things about the rosewoods. If I ever a long and straight enough piece of any rosewood species I would try it.

[mullet]

I've made a self bow out of China Berry and Jacaranda. They both will make a bow but they were sluggish with lackluster cast.

[Joec123able]

I don't get why specific gravity is relevant it's just the density I believe which is why woods with a higher SG then water sink

[DavidV]

Ugh, this site has caused me some grief...

Basically, yes you can use these numbers. The crushing strength is the same as the compression on the belly of the bow, the Modulus of Rupture is the tension on the back of the bow (assuming it is a homogeneous material). Modulus of elasticity is the woods resistance to bending, specific gravity is the density, weight is pretty obvious. All can be useful if you know what you're looking at. Someone linked their article on "Bow Numbers".... I don't agree with it personally and have been playing around with better equations. I'm having trouble creating something that actually explains why osage and yew are good bow woods, The Index of Merit(Stiffness per weight) equation puts them lower than hickory which makes little sense to me. I'm currently having a discussion on another site but I'm not getting anywhere with it. For right now you can do a simple MOR/Compression and compare the ratios to known species. Woods that fret have skewed ratio towards tension.

Here is a spreadsheet I created in Google Drive, had another one a while ago but it was lost. Jim Davis may still have them saved somewhere.

https://drive.google.com/file/d/0B5GmFhNj7jLNLWdRdDVsRl9WSDg/view?usp=sharing

[DavidV]

Here, just did the formatting really quick. The woods on top are tension strong, the ones on the bottom are compression strong. This is for selfbows though, if you make laminates you can mix and match to get the "Perfect ratio" whatever that may be.

https://drive.google.com/file/d/0B5GmFhNj7jLNQmNMWk52TWFSakk/view?usp=sharing

Also the thing is, wood varies a lot by species so you may have an good piece of Bitternut hickory which may be better than an average piece of pignut hickory.

[BrokenArrow]

You have to consider the moisture and relative humidity in the area you are as these will affect the performance.
I a dry climate where I live I would warn against backings for laminate bows that are not hickory. Beware of maple and ash.
Cores are easier to match up and I favor maple and jatoba for those.
In dry climates hickory is king but not in wet climates.
SG should be .5 or greater on all woods used for bow making.

[scp]

For right now you can do a simple MOR/Compression and compare the ratios to known species.

Thank you for the table. That information is more useful in designing a bow for a specific species than comparing different species. I sometimes use the ratio to decide the amount of trapping, if any.

Have you tried to figure out what combination of the statistics can show us why yew and osage orange are special? I did think about it for a while and thought I had a heuristic rule. But now I just cannot find the rule anywhere in the computer I'm using.

[DavidV]

For right now you can do a simple MOR/Compression and compare the ratios to known species.

Thank you for the table. That information is more useful in designing a bow for a specific species than comparing different species. I sometimes use the ratio to decide the amount of trapping, if any.

Have you tried to figure out what combination of the statistics can show us why yew and osage orange are special? I did think about it for a while and thought I had a heuristic rule. But now I just cannot find the rule anywhere in the computer I'm using.

Well, for Yew the data is definitely skewed since only the heartwood was tested. I assume its ratio would be closer to osage. The other problem is that most of the information osage was estimated though we know seasoned osage is much stiffer.

I still have no idea why they are the best bow woods...

Another thing you you can do is plug in the information for laminates so put the MOR for hickory/the Comp. Of osage. It ends up being nearly 1/1, so the neutral plane is in the exact middle of the bow.

[Joec123able]

These number dont make me question why Osage is considered the best all you have to do is make a bow from Osage and you'll know it's the best no matter what numbers on the internet say