First off, I'm not a bowyer. Never claimed to be, don't want to be. I've made exactly one selfbow in my life so far, and that was with a lot of adult supervision. That may be the only one. It didn't break, so I may quit while I'm ahead.
I am, however, a string enthusiast (or, as my friends put it, "string nerd"). I'm a bit OCD about it. I've been studying strings and string materials for 20 years or so, and have developed a pretty reliable network for information when I run across a question I can't answer, including some of the world's best traditional bow hunters, target archers, coaches, and the world's top bowstring manufacturer. I quit counting the number of strings I've personally built at 10,000 several years ago. Probably closer to 20,000 now, but point being you can't help but learn something after that many strings.
On to the topic.
Back when I got into this stuff, some 20 or so years ago, one of the first "rules" I ever heard about string length was "3 inches shorter for longbow, 4 inches shorter for recurves". I found out through trial and error that this rule was right on the money...sometimes. Other times, it missed by a mile.
Along comes the www and personal computers, and websites and message boards for the traditional archer. Whoo-hooo!! My prayers had been answered! Well, not really...I found out that pretty much everyone else was just as in the dark as I was. A certain string length might or might not fit a particular bow. Why wasn't there a standard???
Met a guy who has become one of my better friends and has helped me out a LOT with technical information on strings. I think it was him who first filled me in on AMO. I'll be dipped...there IS a standard! It's been around since 1967, and hasn't changed!
http://www.outlab.it/doc/amostd.pdf Then the bad news again...seems that more bowyers didn't than did know about it and/or follow it. Arrgghhh!!!!
Fast forward to the present.
AMO Bow Length specs have absolutely nothing to do with bow design, draw weight, draw length, etc. You won't have to adjust a design to fit the specs. Simple version is this: Measure the string that puts your bow at the proper brace height. Add three inches. This is the bow's AMO length. That's it.
It DOES NOT MATTER if it's a longbow, selfbow, flatbow, horsebow, or recurve. It DOES NOT MATTER if your bow's correct brace height is 2" or 12". It DOES NOT MATTER what the physical length of your bow is, strung or unstrung. If a 57" string is what fits your bow and puts it at the correct brace, then you have a 60" AMO bow. Period.
The AMO BOW LENGTH actually designates STRING LENGTH. Well, if it's all about string length, why is it called bow length? Danged if I know. Ask an engineer. Or a Cajun. They talk backwards like that. It is what it is.
All that being said...why in the world don't bowyers, especially those who don't follow the standard, make it a point to label their bow with "ASL - XX"..."XX" being the actual string length that fits your bow?
I know...you don't want to confuse anyone about the bow length. Hey, write your bow length loud and proud on both limbs with fluorescent ink. Make it so you have to close the curtains for the neighbors to sleep because of the glare. But somewhere...maybe in tiny little letters on the side of a limb on a 1 piece or on the limb butt on a take-down...do your customers this gigantic favor that will only take you a few seconds and may save them from a nervous breakdown. If the cost of the extra 15 seconds and ink is a concern, tack on an extra 35 cents to cover it.
Seriously...can anyone think of a good reason NOT to put the ASL on a bow that has it's own rules concerning string length?
Topic: AMO Bow Length (Read 987 times)
