This video will wrap up the board bow series where we make a primitive long bow from a maple board we picked up at Home Depot. At the end of part 3 we shot the bow through the chronograph and were shooting around 136-138 fps which is ok, but certainly not great. In this video we talk about how bow design influences the speed and efficiency of a bow. We also talk about the trade offs between a very safe design, like the board bow we built, and more high performance designs.
To get started I show an easy method for measuring the draw weight of the bow using a common bathroom scale. Then we shorten the bow a little to raise the weight and reduce limb mass which will have the added benefit of increasing the efficiency of the bow. After shooting the bow through the chrono for a second time, I reduce mass in the limb tips to reduce inertia even more and we squeeze a little more speed out of the bow.
To wrap thing up, I shoot my 50# osage recurve, the bow I hunt with, through the chrono just as a comparison. Even though my hunting bow is drawing only 50 lbs at 29 inches, it shoots the same arrow much faster than the straight limbed maple bow. This doesn’t have so much to do with the materials the bows are made from, but has everything to do with the design of the bow. This video is a great primer for thinking about bow design and how that influences performance. If you’re interested in getting the most out of the bows you make, check out the Traditional Bowyer’s Handbook. I discuss all these things in much greater detail in the book. There’s even a chapter on how to make a two piece takedown!