Wood Strength Chart

[DavidV]

I've been using a neat site for my wood properties information but comparing multiple woods was difficult. I made this excel spreadsheet with all the necessary information I need of the common (and uncommon) bow woods. These are just American domestics but I have plans for exotics for backed bows and such.

Oh and sorry if the type is too loud, it's meant for print.

[DavidV]

No particular order although I tried to match related species.

and here's the origional website. http://www.wood-database.com/

[Jim Davis]

David, that is a very useful chart. I have been using the Forest Products Laboratory data for years and have made a few charts similar to yours in Word, but yours is far easier to use.

I tried to sort the data according to the elasticity and got a message that the operation could only be done if the "merged  cells are of exactly the same size." So, I tried to sort for specific gravity, because it looked like those cells were of the same size, but got the same message.

Can you sort your original by elasticity, or s.p.?

Jim Davis

[rossfactor]

I like the chart and I use the wood database a s a reference sometimes also.  I do have some serious doubts about some of the data here. 

It seems like crazy and wrong to me that woods like mountain ash, yellow birch and red oak are rated at a higher elastic strength than Osage, Yew and Hop Hornbeam.  I have no data to back this up, but it feels wrong.  I wonder if elasticity is measured based in green or kiln dried wood.

[WoodMunkey157]

Could someone perhaps give a brief breakdown of this data, the subgroups the data is in, and its correlation to the wood and performance? Not looking for an in depth analysis by any means, just something to make the data a little more understandable to a guy like me!

[Weylin]

I agree with Rossfactor. Some of this data seems a little suspect.

[Hrothgar]

DavidV, I think your chart is a good idea, I've visited that website several times. Anymore I tend to regard it with a grain of salt. I don't so much doubt the info as I doubt my ability to understand or implement the info. For example, Persimmion is rated denser and more elastic than osage (or about any other wood) but rarely do you see guys making bows with it. Also, sweet gum is rated similiar to the elms, yet I know when my grand kids attempt to climb the one in my front yard the limbs bend and snap without much resistance, much like a cherry tree.  Most bowyers will tell you that shagbark hickory is the top choice of the hickories, yet in the chart two other hickories are supposed to be more elastic. An another important factor for  good bow wood is how quickly the limbs will recover after the arrow is released. I'm not sure this factor can be predicted using the wood chart. Nonetheless, this is still good information to have charted.

[Onebowonder]

Have any of us ever asked to people over at Wood-Database for an explanation of the numbers they have posted or our confusion over some of the things that appear odd to us?  What kind of responses have you gotten?

OneBow

[Jim Davis]

DavidV, I think your chart is a good idea, I've visited that website several times. Anymore I tend to regard it with a grain of salt. ... For example, Persimmion is rated denser and more elastic than osage (or about any other wood) but rarely do you see guys making bows with it. ...  Most bowyers will tell you that shagbark hickory is the top choice of the hickories, yet in the chart two other hickories are supposed to be more elastic....

The information in the chart appears to have been copied from the data presented long ago by the Forest Products Laboratories. It is good data. The one exception I have found is that FPL never recorded data for DRY Osage. The website that is the source of David's chart notes that its data for dry Osage is an estimate (because no test data is known).

For the hickories,  however, pignut is the strongest in every measure I have ever seen on any chart. All the hickories are good, but pignut is the best. Those bowyers who say shag bark is the best are demonstrating how experience is compiled from anecdotes, and 1,000 anecdotes do not constitute either a statistic or a proof.

Yellow birch is always way up in the charts, as are black locust. persimmon, and serviceberry. Persimmon had quite a following in the middle of the last century. Hornbeam and white ash have similar numbers.

<a href = "http://www.fpl.fs.fed.us/research/centers/woodanatomy/techsheets_display.php?geo_category_id=2&genus_commonname_criteria=c&sorting_rule=1a">forest products laboratories</a>

[rossfactor]

Jim,

Elastic strength is a measurement of the ratio of stress placed upon the wood compared to the deformation (lets call it set ) that the wood exhibits along its length.   

I will take a piece of yew and apiece of red oak, of the same dimensions, dried to the same moisture content and submit them to the same stress, and I'll eat my hat if the red oak takes less set (or is deformed less).

Gabe

[k-hat]

Jim,

Elastic strength is a measurement of the ratio of stress placed upon the wood compared to the deformation (lets call it set ) that the wood exhibits along its length.   

I will take a piece of yew and apiece of red oak, of the same dimensions, dried to the same moisture content and submit them to the same stress, and I'll eat my hat if the red oak takes less set (or is deformed less).

Gabe

I don't think it should be called set.  My understanding of this is simply how much it bends under a load, just like when you spine your arrows, not how much deformation it retains when the load is removed.  Just sayin

[rossfactor]

Oh, maybe I'm confusing elastic strength with the tendency of a material to be deformed plastically e.g. retain its deformation, under stress.  For some reason I thought that was elastic strength. My bad then.  Been outta school too long already 

Gabe

[Bryce]

The data seems a bit sketchy.....
They must not be bow makers over at the lab

[blackhawk]

No offense...but to me these data charts are pretty useless to me...in my opinion other bowyers experiences is waaaaay more trustworthy than some lab test not aimed for bowyering. When I go to use a species of wood I've never used before I research and find out who's used it before and what worked and didn't worked for those folks,and go from there. I have used woods that no one else had ever documented using before as well,and I gauge the wood by its mass as a bow using the mass principle. Sometimes "experiences" are a better teacher,than some classroom/lab numbers.

[Jim Davis]

No offense...but to me these data charts are pretty useless to me...in my opinion other bowyers experiences is waaaaay more trustworthy than some lab test not aimed for bowyering. When I go to use a species of wood I've never used before I research and find out who's used it before and what worked and didn't worked for those folks,and go from there. I have used woods that no one else had ever documented using before as well,and I gauge the wood by its mass as a bow using the mass principle. Sometimes "experiences" are a better teacher,than some classroom/lab numbers.

All engineering tables of mechanical strength are to be used as indications of what can be expected from a material  under certain conditions. Wood is not a uniform material, even within one tree. But the FPL tested hundreds of samples of each wood to come up with an average of the data.

Every stave any bowyer uses may deliver entirely different  results than the next stave of the same wood.  FPL's data might never prove to be an accurate predicter for any stave we ever use. But the data does display the average relative strengths of woods.

The opinions of bowyers will change over the years of their work, but the average strength of varieties of woods does not change. The data tables are a quick way to get an idea of what to expect.

Jim