AMO and String length?

[Ray091]

I have 2 bows a 50# - 58" AMO & a 40# - 60AMO I was given 4 strings 1 custom made and 3 store bought and told they would fit my both my bows.

I measured the strings and they where 55" exactly; 55 3/4"; 57 1/4"; and 58 1/2" I presume that the 2 short strings are for the 58 AMO?

I went online to learn about AMO & string lengths but there seems to be 2 or more methods to determine what the string length should be.

one said 4" for all bows and one said 3" for recurves and 4" for long bows and another said the opposite 4" for recurves and 3" for long bows

What does the majority of the members here say?

Also why the difference in length? should I measure all strings myself before buying and that is both for custom and off the shelf strings?

[kevsuperg]

I've always used 3" shorter on recurves and 4" on longbow. No wait 4" on recurves and 3" on longbows.
Really it's not too critical unless your anal about this stuff, as long as you're 3-4" short the string can be twisted/ untwisted to tune brace height.
Im sure others will chime in, this is just my experience but I'm not sure I've ever had a string that was spot on in length anyways.

[DanielB89]

Ray,

you have now learned why I HATE AMO specs..  You don't really know what you're getting into.  Typically, I like 3.5" shorter on AMO recurves and 2.5" short on AMO lonbows. But have had to make several of them again.  

the BEST thing for you to do would be get the 55" string on the 58" bow and the 57" string on the 60 inch bow.  Twist it up or do whatever you need to get it at the proper brace height.  Then, if the string is too twisted, see if one of the others will work, if not you know what Actual String Length(ASL) to order.  

If you need any further assistance, don't hesitate to pm me.  or email me at hcbstrings@gmail.com

Daniel

[Ray091]

Thanks all for the info.
Daniel I will give that a try thanks

[LBR]

Here's a link to AMO specs.

http://www.texasarchery.org/Documents/AMO/AMOStandards.pdf

Here's what it says about string length and the marked bow length:

AMO Bow Length Standard is designated to be three inches longer than AMO
Bow String Master that braces bow at proper String or Brace Height. Bow String
Master will carry only the bow length designation. Example: A Bow String
Master designated as AMO 66" (bow length) will have an actual length under
tension of 63".

Bowstring/cable length shall be designated by placing the string/cable loops over
1/4" (6.4mm) diameter steel pins. Zero (0) turns of twist are to be inserted in the
bowstring/cable before tension loading. Flemish splice strings are exempt from
twist limitations. Standard tension loads are listed below. Length measurements
are to be taken from the outside of the top steel pin to the outside of the bottom
steel pin after 20 seconds at load.

The AMO length would be great, IF not for two things.  #1, lots of bowyers don't follow AMO specs.  #2, lots of string makers aren't familiar with actual AMO specs so they don't follow it either.

I ask for actual string length measured under load.  That's the most accurate way I know of.

[Bladepeek]

Chad's advice above is absolutely correct. Since I have no way of knowing if the bowyer followed AMO specs when marking the bow length, I use a string I think may be close, twist it up or down to get the correct brace height (usually in the middle of the bowyer's recommended brace height if I'm starting with a new bow) and then measure that string length. This puts me in the ball park where I can fine tune the brace height for best performance.

I have yet to be disappointed by a string I've received using Chad's recommended measurement and I have strings by 3 different Trad Gang string makers. Just seems unfair to expect a string maker to use a crystal ball to decide what string I need.

[Wednesday Caste]

I'm setting up a bow for my 12/13 year old nephew. It's a Ben Pearson 7064 All American 30# 64"AMO. I've refinished the bow and purchased target arrows for him. I do not have the original string for the bow so I bought a 60" (measured 59.5") string and the resulting strung brace height is 9.5".  A web search shows that optimum BH to be 7-8". What length string do I need to get so I end up with a 7-8" brace height?  Thanks guys.

[Bladepeek]

If that string is a flemish twist string, you can probably untwist it far enough to reach the desired brace height. It might be untwisted too far to shoot it that way, but you could brace the bow, check the brace height and then measure the string using Chad' suggested method. Then just order that length string - actual, measured length.

[LBR]

A 61" string should get you there.  E-mail me at chad@recurves.com and I'll see if I can help.

Chad

[jamesh76]

Ray-  I have a 58" amo string I ordered a few months ago and no longer have that bow.  I think it is 54 1/2"  should work on your bow.  If you would like it just send me your address and I will get it in the mail.   James

[Dave Worden]

As always, Chad's the man when it comes to strings!  I will add, however, that the AMO booklet is available on TG in the How To section.  Been there for years.
http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=2;t=000088