# stretching bow string while fabricating



## pernluc (Jun 18, 2006)

*string tension*

100-300 pounds or until the string has a good twang like a guitar.


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## Spotshooter2 (Oct 23, 2003)

With todays materials you arent going to stretch them too far to damage them going to even 500 lbs tension on them. I use a lot of 452X and each strand is supposed to support 75 lbs. On the cables I use 24 strands so that would mean it can hold 1800 lbs so no worry on my jig of damaging the fibers. My jig will go to 330 lbs of tension and has made it a whole lot easier to make good strings and cables.


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## Joe P. (Jan 13, 2004)

I have a question maybe someone could answer, when you serve the string or cables do you twist the string before you start, keep the strands straight or just let the serving twist the strands as you go?


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## Spotshooter2 (Oct 23, 2003)

Twist the strands before you start serving. If you dont , then you are going to have problems with peep rotation because the strands are going to be trying to twist under the serving till they get evened out.


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## asa3dpro (Dec 31, 2002)

*And.*

If you wait to twist after serving the serving will become loose because twisting brings down the diameter of the string and will cause separation.

Robert


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## Deezlin (Feb 5, 2004)

Spotshooter2 said:


> Twist the strands before you start serving. If you dont , then you are going to have problems with peep rotation because the strands are going to be trying to twist under the serving till they get evened out.


Yes, I agree. If you can build a string to length, uniformly twisted and tensioned, you will have no problems with peep sight rotation. 

If you read Brownell's technical information, they recommend 300# tension as sufficient tension. I have also been told the same thing from the General Manager of BCY. The reason is Vectran starts to separate from the other fibers. I personally, can not see any benefit for going over 300# in tension for bowstrings or cabling with today's string materials. http://www.brownellarchery.com/prod-technical.htm

I build and serve all my strings and cables at 300# tension. This allows the strand bundle to be served without inducing uneven twisting. It also elongates and contracts the strand bundle, the serving will tighten as the strand bundle recovers.


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## outdoorattic (Feb 25, 2006)

Twist first


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## Deezlin (Feb 5, 2004)

Joe P. said:


> I have a question maybe someone could answer, when you serve the string or cables do you twist the string before you start, keep the strands straight or just let the serving twist the strands as you go?


The general practice for string making has been to build them straight and then twist after. This is a carry over from recurve string days and doesn't work well on compound strings and peep sights.

I always try to create a string which is to the length specified, uniformly twisted through out it length. Then I mount it on the bow and make any adjustments with the cablings.

This is basically why, I developed my jig. I wanted to be able to precisely measure the string and predict the final length of it.


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## Spotshooter2 (Oct 23, 2003)

Another benefit to Deezlins jig (there are many) is when you go to twist your string Deezlin developed these washers that you put in the middle of the two string bundles out on each end and when you twist the string the washers force the twisting to start at the center of the string and work outwards in both directions. This keeps the twists even from one end to the other , plus on his jig you dont even have to take the string off the jig to do the twisting. It is a great product and I really love mine.


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## theTarget (Sep 4, 2006)

ok, 300# seems to be the right thing.
But how long do you apply this? 
One minute, one hour, a day?


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## bdca (Apr 9, 2007)

*Duh!*



Deezlin said:


> The general practice for string making has been to build them straight and then twist after. This is a carry over from recurve string days and doesn't work well on compound strings and peep sights.
> 
> QUOTE]
> 
> ...


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## Deezlin (Feb 5, 2004)

bdca said:


> The last string I made was in the 70s out of yellow Kevlar. I just built my first usable compound string and twisted after. Now I am getting 1/4- 1/3 turn of peep rotation.
> 
> Is it worth salvaging the string by reserving or should I just toss it. Will it "settle in"?
> 
> I can serve under 250# or so, maybe a bit more.


As long as you are getting uniform rotation you are OK. Unfortunately, that may change. It depends on the temperature ranges you are shooting in. If you are an indoor shooter and you have a little uniform peep rotation in the string, it really shouldn't be a problem. Now, you get much more than a quarter and the D-loop will probably slip on you. 

The real problem with this little bit of uniform rotation is temperature will change it. It may have worked all year during the 3D season, but if you pull it back at 20 degrees hunting, it may or may not rotate properly.

I can do this on my jig where as a lot of other jigs you can't. After I have my string twisted and ready for serving, I increase and decrease the poundage of tension from 0-300 pounds. I watch the string for any sign of twisting. If it twists, I will start working with the string until it will pass this test. Usually, the string does not twist though.

I bought a new color of strand material. I had been using the same product for quite some time. This color when used with another would twist. It didn't matter how I try to make the string it twisted. It works fine by itself, but not with the others. Making multi color strings will probably give you problems unless you can get a good uniform twisting and tensioning. Even then there can be a variation of the strand material.

I usually serve at 300# of tension. As I complete a section of serving, I raise and lower the tension of the string again. This checks to see if I have loaded the string in the process of serving.

Another lesson learned is not all serving is going to produce the same results. One of my favorite serving, I have had problems with on Mathews strings. I would go through the testing and serving for the cam servings and the string was not rotating. When I did the long idler wheel roller guard servings, I got an induced twisting in the string. After trying several other methods without success, I switch servings for this section and the twisting went away.

My proceedures are too lengthy to list here, but I invite anyone interested in string building to buy one of my DVD's. It is $10 plus $5 for shipping and is approximately 100 minutes long. It is divided down into short sections which show specific area. I will refund the $10 if you later decide to buy a jig.


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## Deezlin (Feb 5, 2004)

theTarget said:


> ok, 300# seems to be the right thing.
> But how long do you apply this?
> One minute, one hour, a day?


It doesn't seem to make much difference. Here is what I like to do.


I twist the string and tension it to 300#
I use a mason line or cord and wrap it around the bundle and compress the string bundle. This gets rid of the rope look as well.
I then reduce the tension on the string to 100# and measure it.
I then make any adjustments by twisting and then retension to 300#
I lower the tension and raise the tension to 300#. Checking for rotation.
At this point, I raise the string to 300# and let it set under tension for about 10 minutes.
I then set it to the side with the ends secure from untwisting for a min. of 4 hours.
After the four hours is up, I raise the the string to 100# and re measure it.
I then raise the tension to 300# check for rotation and begin serving.

Now, I have done some experimenting and measuring. I found that there was no substantial increase in elongation after 10 minutes of tensioning. Also, the string material will take time to recover from this stretching. The initial measurement after stretching is an approximate guess, at what the final string will be length wise. The one after the rest period is to set the final dimension. Through experimentation, I have some idea of how much to allow for recovery. This is why, I wait 4 hours before starting the serving application. The string without serving will recover within 4 hours to its final dimension.

Once the string is served and removed from the jig. It will again need to recover. Since it has already been stretched to 300# the application of serving will slow down the recovery, but it will not stop it. The string will need to recover to its final length before it is placed on a bow and this usually takes from 12 to 24 hours depending on the serving lengths involved.


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## FS560 (May 22, 2002)

I do not believe in excessive tension on a string during construction and therefore limit it to about 100 # on the string jig.

After serving the loops, I twist the string and tension it before serving the ends.

Then I install the string on the bow, get the length right, and draw it about 30 times to seat the strands in the end serving around the cam tracks.

Then let it sit overnight and draw it another 20 times in the morning and let it sit until evening.

Then and only then do I serve the center with the string still on the bow.

The peep never rotates.

Obviously, I only make strings for myself, no one else would pay the price I would have to charge and then it would not include the seating of the string to the cams or letting it seat overnight before installing the center.


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## bdca (Apr 9, 2007)

Deezlin said:


> My proceedures are too lengthy to list here, but I invite anyone interested in string building to buy one of my DVD's. It is $10 plus $5 for shipping and is approximately 100 minutes long. It is divided down into short sections which show specific area. I will refund the $10 if you later decide to buy a jig.


$15 on the way via PayPal...


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## bdca (Apr 9, 2007)

I built a new string on Friday uisng the above suggestions and had almost no peep rotation. The peep finally settled in at a 1/4 turn (when relaxed) which I corrected with a twist.

I stripped the old string twisted and reserved it as a spare.

Thanks!


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## theTarget (Sep 4, 2006)

how do you measure the 100# and 300#?
Is it some kind of experiance or guess?
Or do you have some measuring device?
Just asking this silly questions because I have to build my
own string soon, shooting for one year now with the original string.


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