Wood compression tension chart??

[Jakesnyder]

First of all forgive me for posting so much lately. Does anyone have a chart for wood compression vs tension? Is there such thing? Thanks

[bjrogg]

Sorry Jake I don't have a chart. I'm sure someone can help you through. No need to apologize for posting to much. I never do.lol
Bjrogg

[Pat B]

Yeah really, BJ never apologizes for posting too much.     
Jake, there is a lot more to it than tension and compression. For instance, locust is one of the strongest woods in compression in North America but it is brittle. That's why it will fret so freely if there is a hinge or the tiller is off. Locust used to be used for bearings but when you put in a bending situation it doesn't seem so strong.
Most, if not all woods are stronger in tension than in compression and with different woods those values are different. When working with different, unfamiliar woods I like to start out with a slightly overbuilt bow. After that I will change the design to test those tension/compression differences. Also when working with wood, every piece is different, nothing set in stone. We have bow woods that we know from experimentation are stronger one way or the other so from anecdotal evidence we build our bows considerate of the differences others have found out. Osage is very strong in tension and compression, ipe is also strong in compression but like locust is is brittle and can fret easily if your tiller is off.
 To answer your question, no, I don't have a chart. There are wood values charts and websites that offer them. Maybe someone will have those for you. But, I think these values are for static wood and not necessarily working wood like with bows.
 Nobody ever asks too many questions unless you don't heed the answers given.

[Badger]

No charts that I know of and the ones that have been created for bow woods are more anecdotal than factual. I have given this some thought and I think the best way to create a useful chart would be too simply do a bend test on Pieces of wood using identical dimensions maybe 8# MC and cut in a pyramid shape. It wouldn't tell much about compression or tension but at least it might be helpful in building a chart on how strong and flexible different woods are.

[Jakesnyder]

Thanks for the info guys! As always a big help for a newb Bowyer as myself

[Bayou Ben]

What Pat said. 
You can get a lot of information on wood database.  Just keep in mind that there's no single value that will determine what makes a good bow wood.  There's a write-up on wood database about a bow index which compares MOR to MOE.  Even that is just a comparison of those 2 properties and the results are subjective. 
A test like Steve is talking about would be more beneficial to the real life bending that wood sees when we make it into a bow.
 

[SLIMBOB]

There is a Wood Database on the web. I believe that is in fact what it is called. Interesting data, but not gonna make much difference in the bows you make. As an example, the data on Black Cherry is really interesting. Lowest hysterisis of nearly all hard woods. Low set. I don’t doubt this, but in my opinion, that simply means it is strong in compression and brittle in tension as a result. Only building a few bows with it will you figure this out and be able to apply it. I believe that to be true for for this craft as a whole. Still, interesting stuff.

[Jim Davis]

The Forest Products Laboratories are the original testing facility for North American woods. The work was done in the 1920s or 1930s, IIRC. This is the source of the North American data in the "Wood Data base."

Also, be aware that FPL either did not test DRY Osage or did not preserve the data.  So Osage in the WDB compares poorly to other bow woods.

Also note that modulus of elasticity, M. of rupture, and wok to maximum load are high for the usual bow woods, with pignut hickory, black locust and Osage excelling.

This chart is useless, but I can't delete it............

[Bayou Ben]

So you are the "James Davis" that commented under the bow index page on WDB?  I kinda figured that was you...