Graphically Designing a Bow Version 2.0

[Wooden Spring]

I  thought that there might have been some discussion on the proportional limit of wood, as the practical working limit for a bow is usually  "how much set did it take"? Perhaps it is assumed to be some percentage of the MOR?  Aren't the differences in how far the wood can bend before taking set where we so often find our preferences for woods like osage or yew?

There was no discussion on proportional limit of wood other than the quote I gave on the stress. Perhaps this maximum thickness IS the upper limit before set is taken in the bow? Set is nothing but a failure in the wood, and the thickness number is meant to be a maximum to avoid failure...   

I believe it was in one of the Traditional Bowyer's Bible's (though I forget which one) that described a standard bend test in order to determine how much a particular wood will bend before taking set, and how much before it breaks. It would seem wise to combine these two areas of thought. Conduct a standard bend test among several possible bow woods, take the wood that reveals the least set for a given bend, and then run the formulas for Bow Design.

[Hamish]

They are a very interesting set of articles primarily written to scientifically understand bows (and arrows), with the aim to make an efficient bow without the need of lots of skills and experience that a good bowyer has taken a long time developing.

They really only bothered with yew, osage and lemonwood, which work well with the relatively narrow width limbs, predominently pyramid limb design, constant thickness circle of arc tiller.
In the later articles Nagler from memory seemed to go away from tillering circle of arc to elliptical, and produced a series of charts for widths and thicknesses, that anyone could use to make a bow from.
I made a couple of bows to this pattern and found them okay, but not as good a bow tillered by my eye, taking into account where to remove wood by where set emerged during making, avoiding too much near the fades whilst also avoiding whip tiller. ie most of the work in the mid limb.

Elmer in Target Archery also has a more comprehensive table devised by someone with a physics /engineering background. I don't think he was one of t"Archery the Technical Side" authors. From my limited experience 8-10 bow variants of this pattern, it produces a better tiller, than Naglers. It is less whip tillered, but I find it gives a little too much set near the fades for my liking.
It certainly would be easier for a newcomer to make a decent, shootable bow this way, but I can still usually make a better performing bow by the traditional method, using feedback from the stave.

Unfortunately for wooden bow junkies the focus moved on to fibreglass, so we never really got to see where the scientific men of the time could really refine their ideas to produce the ultimate wooden bow, to rival a master bowyer.


I'm not saying no one should try to have a go at these experiments, they would be beneficial for anyone with an inquiring mind. I'm not knowledgeable enough in the necessary scientific fields to pursue the idea further, but I'm sure some of you guys are. Who knows what fresh eyes, and minds will develop.