A tale of 5 Yellow Birch Bows / great bow wood not often seen

[PrimitiveTim]

Love those bows!  The coral snake bow is pretty sweet too!

[simson]

What a great line of bows. Like all of them. I admire your work, Rich!

[4giveme]

hi rich, some really nice looking bows. i was wondering if you ever went to a site www .wood-database. com. they have all the info on all woods and there characteristics. just a little sample:

Common Name(s): Osage Orange, Horse Apple, Hedge Apple, Bois d’arc

Scientific Name: Maclura pomifera

Distribution: South-central United States

Tree Size: 50-60 ft (15-18 m) tall, 1-2 ft (.3-.6 m) trunk diameter

Average Dried Weight: 54 lbs/ft3 (855 kg/m3)

Specific Gravity (Basic, 12% MC): .76, .86

Janka Hardness: 2,760 lbf (12,280 N)

Modulus of Rupture: 18,650 lbf/in2 (128.6 MPa)

Elastic Modulus: 1,689,000 lbf/in2 (11.64 GPa)

Crushing Strength: 9,380 lbf/in2 (64.7 MPa)*

*Estimated crushing strength from data of green wood at: 5,810 lbf/in2 (40.1 MPa)

Shrinkage: Volumetric: 9.1%
************************************************************

Common Name(s): Hophornbeam, American Ironwood

Scientific Name: Ostrya virginiana

Distribution: Eastern North America

Tree Size: 40-60 ft (12-18 m) tall, 1-2 ft (.3-.6 m) trunk diameter

Average Dried Weight: 49 lbs/ft3 (785 kg/m3)

Specific Gravity (Basic, 12% MC): .63, .79

Janka Hardness: 1,860 lbf (8,270 N)

Modulus of Rupture: 14,100 lbf/in2 (97.2 MPa)

Elastic Modulus: 1,700,000 lbf/in2 (11.72 GPa)

Crushing Strength: 7,760 lbf/in2 (53.5 MPa)

Shrinkage: Radial: 8.2%, Tangential: 9.6%, Volumetric: 18.6%, T/R Ratio: 1.2
**********************************************************************

Common Name(s): Live Oak, Southern Live Oak

Scientific Name:Quercus virginiana

Distribution: Southeastern United States

Tree Size: 40-60 ft (12-18 m) tall, 4-6 ft (1.2-1.8 m) trunk diameter

Average Dried Weight: 63 lbs/ft3 (1,000 kg/m3)

Specific Gravity (Basic, 12% MC): .80, 1.00

Janka Hardness: 2,680 lbf (12,920 N)

Modulus of Rupture: 18,220 lbf/in2 (125.6 MPa)

Elastic Modulus: 1,960,000 lbf/in2 (13.52 GPa)

Crushing Strength: 8,810 lbf/in2 (60.8 MPa)

Shrinkage:Radial: 6.6%, Tangential: 9.5%, Volumetric: 14.7%, T/R Ratio: 1.4

[okie64]

Good looking bunch of bows Rich! The only birch we have around here are the ones that lean out over the creeks and rivers and we call them river birch so Im guessing those arent the same as yellow birch. Oh well nice bends you got on those sticks.

[Slackbunny]

I had just recently made a bow from yellow birch. It was a screamer that came in heavier and faster than I expected. I was pleasantly surprised with how well I liked it. I'd made one before that too, but that was when my skills were pretty lacking and I didn't have the experience to know what I was working with.

I was going to make a thread just like this with my bow as the poster child for yellow birch. But then as I was getting ready to take some pictures I was excerising the bow and it popped a splinter on the back. The crown was too aggressive I think. Lesson learned.

But I'm glad someone as experienced as you can corroborate the same things I had found about this bow wood.

[half eye]

Looks like maybe this might be useful

4g-m, thanks for the info, will get that into the mix here asap.

Hey Okie, glad ya aint gone belly up, bud

slack, Never seen your bow, but all these are some sort of rectangular section with the sharp corners "mildly" rounded off. I have found that you get good results if you match the belly and back profiles that is flat/flat or low crown/low crown. The only exception in the posted bows is the concave back stave and that belly is flat and carefully tillered.

The map below is the "Native Range" of yellow birch, but I do believe that it's grown other places maybe as an ornamental or some such. There is also a picture of the "inner-bark" so ya can see just how thick it is (edge of a quarter sawn homemade board)

really hope you all get a chance to at least try this stuff.
rich

[IdahoMatt]

I love your bows Rich.  These are no exception.  Great job man.  I wish we had some yellow birch around here.  All we've got is water birch I think.  Grows pipe strait and long.  I'll have to try some sometime.  I know it's nowhere near the density though.  Great bows I really like the first one

[IsaacW]

Very nice.  I have a yellow birch rough sawn board that I am planning on turning into a pair of skis.  After that... maybe there will be enough left for a board bow! 

[H Rhodes]

Those look great Rich.  The only birch we have is river birch.  I haven't tried it yet, but it is on my list of woods to try. 

[4giveme]

Good morning HE,
To use the info I posted earlier about the wood data base to be use full one must read the article that I will provided below. Tommy

by Eric Meier
Disclaimer: I am neither a bowyer/archer nor a materials scientist/engineer. The data and ideas presented in this article are by no means meant to be considered authoritative or precisely correlated to real-world situations. The purpose of the article is simply to foster imagination and exploration in the area of bow woods and what does/does not constitute a good bow wood.
Archery bows present a somewhat unique challenge in finding the right requirements for the best wood. In the simplest and crudest terms possible, the wood should be able to bend, but not break. With all of the data available on the Wood Database, there’s no single measurement that directly indicates a wood’s ability to bend easily without breaking. Instead, it is primarily a combination of two values: the wood’s modulus of elasticity (also known as MOE), and the modulus of rupture (also known as MOR).
Again, dealing in the simplest terms:
The modulus of elasticity (MOE) measures how easily a wood will bend, (the higher the number, the more stubborn and stiff it will be).
The modulus of rupture (MOR) measures how easily the wood will break, (the higher the numer, the harder it is to break or rupture).
In terms of looking at the raw mechanical data of woods, the best bow woods tend to be those that have a low MOE and a high MOR. (Stated another way, the best bow woods tend to be those that will bend easily, and not break.) It’s of little advantage if a given wood scores well in one area, and poorly in another (i.e., a very low MOE or a very high MOR). What is most important, regardless of how low the MOE may be, or how high the MOR may be, is the ratio of the MOE to the MOR; it must be easy to bend AND hard to break.
Given the rationale and requirements, an equation can be formed to roughly assess a wood’s suitability for bow use: (MOR/MOE) * 1000. (The added factor of 1000 is simply to bring the number to a more manageable size and avoid dealing with tiny .00xx decimal values.) For lack of a better term, this ratio will simply be referred to as the wood’s “Bow Index.”
Analyzing all the woods in the Wood Database for their Bow Index, the following results are obtained:

[Badly Bent]

Got my radar up for some yellow birch now, not sure when or if I'll run into any of this stuff around here but the sharp handsaw is always in the truck. Nice bows all around Rich, you know I like your style.

[half eye]

Thanks again fellas,

Badly Bent, Idaho Matt, Howard.....got 3 sticks settin in the work room (shop and shed are still buried)2 are 72" and the other is shorter. Please PM your address's and I'll give these to you, maybe you could cover the shipping? That is if you dont mind working with a homemade board. The broad surfaces are planed flat both sides.

4give me: The way I utilize my charts is by direct comparison, in other words I dont really care what the scientific importance is in the actual numbers....I can directly compare a "new" wood to ones that I know are good bow woods and have a fair sense of it's suitability and how to approach the project. The static bending dynamics are directly involved in suitability for bow wood so by comparing the unknown to the known and using the numbers (metric or inch/pounds) as the gauge, I get a starting point.
rich

[Badly Bent]

Heck yeah Rich, I'll give it a go. Gotta head out right now but I'll send ya a pm when I get back and have a few minutes to do some of my one finger typing.

[George Tsoukalas]

Rich, your bows are truly works of art. You are not only a talented bowyer but an artist as well.
Jawge

[George Tsoukalas]

Rich, your bows are truly works of art. You are not only a talented bowyer but an artist as well.
Jawge