Primitive Archer

Need an update please guys

When I lived in Maine, BL was the best wood I could easily get.

My first use of it was from a small tree that only allowed a 1-1/2" wide stave. I made a pyramid design bow that was nearly perfect tiller at #35. It had about 3 inches of  reflex. I shot it a lot and it performed well. Then I discovered that the belly had a parade of frets from one tip to the other--the whole belly.

With nothing much to lose, I just kept on shooting it. Eventually, I over drew it and it broke.

For the next few years, I made all my bows with backs narrower than the belly. But my subsequent research found studies that indicated that wood only stretches about 1% before breaking. SO, narrowing the back does not make the tension wood stretch more to accommodate the compression of the belly.

We all know that if we bend any piece of wood far enough, it WILL break. The balance for bowyers is in making the limbs thin enough to not yield (take set) at the amount of bend (draw length) we want. At the right thickness for the bend, the weight will be determined by the limb width.

My best locust bows were pyramid design, a little under 1/2" thick, 2-1/2" wide at the fades, 68" NTN and about #40 at 28".

Put two different arrows through the chronograph today, with two different bows. Just out of curiosity and for education's sake.

one arrow is 575gn, the other 300gn.

One bow pulls 50#, the other pulls 43#. Both drawn to 28 inches.

Here are the results

50# pyramid reflex shot a 575gn arrow at 140fps. Chatgpt (i know lol) estimates for a 10gpp arrow this would be between 148-153 fps. Not bad.

With the same bow, the 300gn arrow was shot 158 fps. I can't promise my release is consistent, but I was trying for consistency in release and draw length.

Next set of photos is a 43# rock maple bow with reflexed tips. It shot the 575 gn arrow at 127 fps. Again chatgpt estimates about the same, 150fps with a 10 gpp arrow. Not bad either.

I cut my bow building teeth on locust. I started buying locust fence posts for $5 each. Made lots of bows but they all fretted. My only success was with an Eastern Woodland style bendy handle bow I made for a bow trade.
 The locust that grows around on our property has something that causes the early growth rings to deteriorate and separate so all of the bows I tried with them have failed. I think there are a lot of variables when it comes to locust, at least around here.

I think that estimating stored energy is quite straightforward. Take the maximum draw weight (DW) and the power stroke (PS), then use the formula 0.5 × DW × PS.

For example, consider a 50# @ 28" bow with a 6" brace height. This gives 50 lb draw weight and a 22" (1.83 ft) power stroke, so: 0.5 × 50 × 1.83 = 45.8 ft-lb.

For a straight bow, this is a good estimate because the draw-force curve is almost linear. For reflex and recurve bows, the stored energy can be multiplied by a factor of 1.05–1.25, depending on how much backset the bow has (more backset gives a higher factor). This factor arises from the draw-force curve being “fatter” for bows with greater backset. For a straight bow, the factor is 1.0, and for deflexed bows it can be under 1.0.

In my opinion, defining a draw-force factor would be the best approach for estimating stored energy for a specific bow. This factor can be determined by measuring the draw-force curve of real bows and/or by modeling it using a program such as VirtualBow.