Getting max draw weight out of my bow?? updated....new ?????

[mallard79]

I had new winners choice string/cable put on my bow a few months ago and have about 400 shots on them. My bow is a 2008 Diamond The Rock with 70lb limbs. I have the limb bolts cranked in. Recently when I was shooting it didn't seem like I was pulling the full 70lbs. When I checked the draw weight with a scale it was pulling 64-65 lbs. is this caused by the strings stretching? Is this something I can easily fix on my own by putting more twists in my string/cable? I am still learning the tricks of tuning my own bow but don't want to screw up because I didn't ask. 

[bigfish]

make sure the cables and strings are the right sizes and if they are you will need to twist them to get your poundage back it can take some work

[Old Dog]

It will take a bow press.  Remove the power cable and put 4 or 5 twist in it.  Check the weight again.  Also check the axle length and brace height.  They should be within 1/8 in of factory specs.

[mallard79]

The string and cable are the correct sizes for the bow per the bow specs.  I will press it and put some twists in it and see what happens. Thanks guys.

[Old Dog]

There will be a minor increase in draw length.  Nothing serious, but you may need to adjust your peep sight a little.

[mallard79]

Ok....I had to put 5 twists in the cable to get the brace height into spec at 7". Now my axle to axle should be 31.563" but it is right at 32". What could cause my ata to be almost 1/2" long? Should I worry about it if it is pulling 70#? The only thing I can think of is that I took the factory rubber grip off and just wrapped the riser with tennis racket grip tape.....it made the grip narrower but may have also changed my brace height? If that is the case should i just twist the cable a few more times to get the ata to the correct length?

[Old Dog]

I've always had really good luck with Winner's Choice strings, but it sounds like yours are a little too long.  Put a few twists in the shooting string, and about half as many more in the power cable.  Do this until the bow meets specs.  It should draw 71or 72 lbs cranked all the way down.

[mallard79]

will do.....Thanks 

[briancorneal]

Winner's choice strings aren't suppose to stretch, and if they do, they've got an awesome return policy.  They should be pre-stretched and have no creep from the factory.

[RadSav]

Most of your Winners Choice strings are 8125.  They creep like a fox in the chicken coupe.  You can order them in 452X, but that is not their standard.  They claim to have no Peep rotation not that they will not creep.  I refuse to use 8125 anymore because my bow goes out of tune every time the temperature rises above 80 degrees.

Your cables see a lot more tension than the string ever will.  With the measurements you made sounds like the cables are the problem.  Making up 3/8" in twists is quite a bit when the Winners Choice strings are already almost a 1 to 1 ratio.  If they are new send them back!  WC is usually pretty good about that kind of thing.  Request 452X on the replacements.

If they won't replace them for some reason go to your Bowtech/Diamond dealer and have them order the Octane strings for it.  Bowtech will guarantee those to fit perfectly on the Rock!

[briancorneal]

Here's what winners choice says straight from their website:

No Peep Rotation...Guaranteed
No String Stretch or Serving Separaration...Guaranteed Weatherproof Technology...Guaranteed
Trusted by the worlds top archers Fast order turn around. commitment to provide the best customer service in the industry.

[RadSav]

Here's what winners choice says straight from their website:

No Peep Rotation...Guaranteed
No String Stretch or Serving Separaration...Guaranteed Weatherproof Technology...Guaranteed
Trusted by the worlds top archers Fast order turn around. commitment to provide the best customer service in the industry.

That is correct.  Their stings will not stretch because the "Life" has been stretched out of them.  However, you notice they say nothing about "Creep".  8125 does creep - period!  Not even BCY will hide that fact.  If you want a cable that does not creep BCY recommends 452X or Trophy.  I prefer Brownells Xcel which is virtually the same thing just more consistant in diameter amongst all colors.

From BCY:
Question: What is creep compared to stretch?
Answer: Creep is non-recoverable elongation, unlike stretch which is basically elasticity or recoverable elongation. Some elasticity is necessary.

Question: Are there any bowstring materials that do not creep?
Answer: Yes - 450 Plus, 452X and Trophy. These are blends of Dyneema and Vectran. Vectran has no creep at the tension created by normal bows; therefore these materials are normally 100% stable.

Question: Does twisting reduce creep?
Answer: Not really. Eventually polyethylene fibers such as Spectra and Dyneema, under high temperature and high tension, will creep. Twisting will take up the stretch (creep) that has occurred, but will not stop it from continuing.

I don't mean to talk you out of a Winners Choice string/cables.  They are good people and make a fine product.  It's just always a safe bet to request 452X or Trophy(452GX) when ordering cables from them.  It will eliminate this type of problem.  I agree, their return policy is very good.

[buckfvr]

So you buy new strings and cables, lengths are correct, ATA, brace height, tiller, timing marks, all correct.  Bow pulls 65lbs instead of advertised 70lb max.  SO you take it out of spec to get 70lbs?  I find it fairly common to run into this,  everything is right, but not up to max limb weight. 

I think at some point, limbs yield.....not much, but certainly enough to make a difference of 4 or 5lbs of draw weight.  Many guys say limbs dont yield,  but there are many tougher man made products that do yield, steel being one of them. 

Again, just my thoughts based on my experiences.  String and cables would be first to yield as they are the weak point in the bows moving parts, but the limbs under constant pressure, and changing pressures, would certainly seem to naturally relax as much as possible.

What say RadSav.....not questioning your obvious knowledge and wisdom, just curious as to your thoughts.  Russ

[mallard79]

Ordered my new Octane string and cable set yesterday. Having a different shop put them on and tune the bow. Then it will be time to get serious about broadhead tuning it. thanks for the input guys. 

[RadSav]

buckfvr - That was very much the case years ago when wood core limbs were the norm.  Even the first machined fiber limbs on the early Mathews, Bowtech, etc experienced these issues just prior to breakage. 

At one time anyone who was anyone shot the Jennings T-Star in competition.  Unlike other companies of that time frame Jennings used a lightweight limb and more pre-stress creating greater speed and a smoother feel.  The side effect, however, was that most competitive shooters carried one or two back up bows and tracked "shots per limb" because the density breakdown was quite rapid.

Over the past decade technology in synthetic carbon fiber and epoxies has improved to such an extent that we rarely see this anymore.  The amount of cycles in a limb is tremendous even with limbs exhibiting extreme preload like those in the PSE, McPherson/Monster and highend Bear.  No longer do we use brittle petroleum pitch fibers that can not retain elasticity. Instead these newer PAN filaments form chains that bond side-to-side forming sheets that eventually merge into a single columnar filament.  Long description short these filaments now have great elasticity, tensile strength and longevity under the loads of the modern bow limb.  A few dozen shots to relax any molded stresses from manufacturing and they should perform without yield for far more shots than the average bowhunter could achieve over many years.

To prove a point Larry Wise once took the Barnsdale laminated carbon limbs from a display bow used by Xi at shows.  These limbs had been dry fired in a special automatic dry firing machine in excess of 3,000 times.  Larry put them on his competition target bow and continued to compete with them for another two years with no yield, breakage or change in performance.

One thing I have noticed is that bow manufacturers sometimes adjust strings and cable lengths to make a particular set of limbs hit weight.  I experienced this first hand with a T2 Darkhorse that was suppose to be 60 pounds.  I took it out of the box and checked the draw weight at 61#.  Since I do not shoot 8125 and prefer a self-adjusting yoke I immediately made a new string and cable for it.  When I checked weight again it was 68#.  I removed the new strings, put them on the jig under 100 pounds of tension (ATA standards) and they measured within 1/32" of manufactures specification.

After a short conversation with my tech connection at Bear I found that they had not made a 60# limb for that bow yet.  Instead they had taken 70# limbs that fell short on the deflection scale and adjusted string/cable lengths to hit the desired 60#.  It shot so dang good at 68# I never made the adjustments to string length and never got the new limbs once they were available.  Instead of a target bow I now have a nail driver of a blind bow. That's it in the picture with my little antelope

Sorry for the book.  Hope that's what you wanted.

[RadSav]

Ordered my new Octane string and cable set yesterday. Having a different shop put them on and tune the bow. Then it will be time to get serious about broadhead tuning it. thanks for the input guys. 

Sounds great!  If you have any problems at all please PM me.

[buckfvr]

Thanks RadSav, great information .  R