Bowsite.com

How to Measure Cables & Strings

What is the proper way to measure a set of cables and strings?

Do you use posts to hold the loops that are the same diameter as the bow's attachment points?

Is the measurements from center to center or outside dimensions?

The specs for cables and strings are precise; so if one uses the wrong start/finish points, or the wrong holding pins, the measurements will be inaccurate.

My string supplier said he measures his strings on a sliding rule he made that has two pegs 3/16" OD. Measure outside of peg to outside of peg with 50 pounds of force.

Most string builders use 1/4" pins at 100# of force - outside to outside. That is the AMO standard.

I appreciate the responses.

Needed to know how to verify lengths when I purchase new cables and strings.

Also, during tuning if I get things all messed-up, I know how to reset to square one.

Unfortunately the AMO does not exist anymore, thus their standards have not applied for over a decade. It would be nice if everybody used a set standard however.

I belong to a group of over 50 custom builders on FB. All of them use the AMO method of outside 1/4" post with 100#'s pressure for final build measurement. It is used for the lengths put on the bow limbs for every major bow manufacturer as well. May not be a written standard but it is the one used pretty much universally. I am sure one can find exceptions.

Not arguing with you Steve, just pointing out the facts to the original poster. 100 pounds is not needed with today's string materials. They don't stretch like Dacron and Fast Flight, which can stretch 1/4" or more between 50 to 100 pounds. Keep in mind the OP was asking how to check his existing strings for accurate length. When I made strings, I kept 100 pounds on them while applying the serving, but if you're checking the length of a completed string at home, even 20 pounds should suffice. With modern string materials the difference between 20 and 100 pounds would be less than 1/32". Seems as though the most important question was to measure from the inside of the loop or outside of the loop. That could make as much as 1/8" difference.

The last issue of the AMO Standards that I received as a member was 1987. A lot has changed since then.

Well, I received a set of custom cables & sting from a reputable builder for my Bowtech Invasion bow. Being very careful not to add/remove any twist, the cable is nearly 1/4” off from the module timing dots (toward the string). In order to get the cables between the dots (at brace), close to 10+ twists to each cable was needed. Got the stops hitting at the same time. The axel to axel (ATA) measurement was too short. Bow didn’t feel right in draw either. Peep angle totally different too. Spent the past five days tuning, shooting, etc. Got the BH and FP hitting the close. Bow just doesn’t shoot same as other bow. Draw cycle much diff. Pulls much harder too. Compared my other Invasion bow to this one. The limbs are bent a lot more and ATA much shorter. Put bow back in press and removed cables and string. Tried to verify measurements, but don’t have an accurate method (yet).

1/4” or 3/16” pins? Makes a diff. Going to my local Bowtech dealer today for assistance.

Seems to me the string is too short.

Thoughts?

How close are the strings to factory spec lengths when you just measure by hand? Pound a nail in the wall of your garage, hook one end of the string over it, pull as hard as you can, hook a tape measure over the nail and measure out to the screwdriver that is in your hand pulling the string. This is not "AMO" but it will be within 1/8".

Prior to reading your post x-man, I made a peg board with a 1/4" dowel and #2 screwdriver. Reset each to manufacture's specs.

ATA is correct, brace is correct.

There's not many twists in the string.

Haven't checked the draw stops yet.

Thoughts?

I really appreciate your assistance. I'm one step away from taking the bow to my local shop.

Register here to reply to this topic