Not sure why I don't know this...

[OkKeith]

In the forty-five years or so I have been playing with bows... I guess I never questioned myself on this (or if I did I never asked anyone). I feel stupid asking about it. Maybe it's really more of a "testing my understanding".

When you measure a bow for string length and you want a NTN measurement, do you stretch the tape as the string would run or somewhat follow the contours of the unstrung bow? I ran a seamstress tape on some of my production bows with a known AMO length and it doesn't track for me. A 60" AMO bow isn't sixty inches at a definite spot that I can find. I measured the following bows:

1964 Bear Kodiak Hunter
1968 Wing Redwing Hunter
1980s Howatt Hunter
1990s Quinn Stallion
1980s Martin ML10

They all were close to their labeled AMO length but not spot on.

I have a couple of bow builds under way and wanted to get some strings made without my usual fooling around with lots of strings to find the right length and then making one that is either too long or too short and then getting one that works.

OkKeith

[Bvas]

Normally it is measured by running a tape along the back of the bow. Some of the more forward handle designs are measured cutting thru the center of the riser.

My understanding is if they are marked AMO, then the string should be 3” shorter than the bow length.

[OkKeith]

Hey Bvas...

Thanks for the help. That was what my understanding always was but none of the production bows I measured seemed to follow that rule. Taking into account stretch and tuning, the bows I measured fell outside the three inch (or four inch) rule.

I guess it doesn't really matter as long as I end up with a string that shoots good on the bows. I have a shoe box full of strings I have made that didn't fit (ipso facto, didn't shoot well) whatever I was making them for. I manage to use one out of the box for a project every once in a while.

OkKeith

[rainman]

I always heard AMO was 4"inches shorter for recurve and 3" shorter for longbow.

[Mark R]

What your describing in my experience seems to be the norm, 3-4 inches may be a good starting point when you don't exactly already know what works. I will from now on just put the max string length on any bow I make, can always twist to find the sweet spot for each draw length,  makes it simple. Wish all Bowyers would do it.