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Board Bow Schematics

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bubby:
Lots of variables to consider, design, wood type length, getting a mathematical equation to do this with a wood bow kinda takes the fun out of it, be almost like building a glass bow

Aussie Yeoman:
There are actually formulae for calculating selfbow dimensions. There are a few bowyers who have sunk hundreds of hours into creating spreadsheets that will give very precise measurements for bows of desired proportions and various statistics.

Nagler, Hickman et al championed the idea of using formulae for making bows.

There are lots of naysayers about who will say that doing such takes away from the heart and soul of wood bowyery. But through the use of such devises and stratagems, Nagler reported he was able to use gnarled, twisted character staves that other bowyers passed over for being too difficult.

Now, I could send you my spreadsheet for making bows, but that'd be cheating. Instead, I will post this link to a long and unfinished series of posts on how to figure it out yourself:

http://ozbow.net/phpBB3/viewtopic.php?f=34&t=5450

With what I've included there, it will be possible to figure out how to mathematically calculate dimensions for a pyramid bow of whatever dimensions you require.

Dave

BryBow:
Well... That's what I'm talking about. I thank you for your reply Aussie. I hope more forum participants will take advantage of your link.

PEARL DRUMS:
Self bows and board bows are totally different critters. If you apply these formulas to a board you will not get the same results unless they tested boards of all different grain orientations separately. 1/4 sawn doesn't compare to rift sawn doesn't compare to flat sawn.

JackCrafty:
Interesting link.  Lots of work went into the answers.

The explanations try to show how math can be be used to create bows with a rectangular cross section and a basically pyramid design.  This is fine if that's what you are looking for.  But you still have to build the bows and fine tune everything.  The dimensions may end up being significantly different.  Bows with trapped/rounded bellies or backs are not discussed, as far as I can tell.  And as Pearl Drums mentioned, the way the wood is cut will affect the strength and bending characteristics.

If you want to get in the ballpark of the dimensions before you start, so you can save yourself some time, then developing formulas may help.  As for me, I can rough out a bow in about the same time as it would for me to crunch the numbers and check my answers.  And then I still have to rough it out and get it floor tillered before I can start the real tillering.

I can see how this might help someone in the beginning of a professional bow making start-up.  After a while, though, the shapes will come naturally as you gain more experience.  Professional bowyers keep track of their final measurements and keep them in a book or something.  This book is usually well guarded because it contains the "secret recipes" that help a bowyer make a living.

Not many bowyers are willing to hand over their recipe book.  That's why this question may not get a direct answer.

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