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Factory Crappy Strings shorter than actual Factory Specs, why?

2326 Views 18 Replies 12 Participants Last post by  nuts&bolts
Why does bow companies provide specific string/cables length numbers but then put shorter strings and cables on their bows before they leave the factory?
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Discussion Starter · #5 ·
Thanks guys for your post. Kinda sucks. I just had some custom strings made to factory spec and now I basicly have strings that are too long. Its ok, staying with the recommended string twist ratio I was able to get the ATA, Brace, and tiller into spec. The only problem is that my draw weight is down by 5 pounds.

Do you guys think that over twisting the cable would have an adverse effect on the performance of the bow?
 

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Every individual bow is diff.The string specs they list is a generalization for most bows to get the proper measurements you should tune the bow then blueprint the strings,this is the only way to get it perfect.Most companies if you order off of their measurements will be descent but some bows out of the box if you take the strings off and measure them they are nowere close to what they reccomend on string measurements but if you twist them up you will find the bow is close to tuned and speced this is do to poor QC and string stretch do to poor quality strings.From what I have seen most bows out of the box the strings are stretched.I have yet to see a company use quality strings on thier bows the issue is that companies will not spend much on strings and they demand large quanaties.If they use outside source it will be hard for that company to keep up and still offer a descent product and the same apparently goes if they build them in house.Just my 2 cents.Every bow I have bought needed tuning out of the box and after tuned the strings were overly twisted which meant they needed new strings,but I generally shot them as long as I could to get the good out of them as I am fruegal not cheap.*I would put the strings on to the lengths they specify then get some tuning knowledge if you do not have that already,I bet you will find the strings were shorter to get the higher poundage out of the bow,but when tuned properly the poundage may be lower but the bow may be closer to properly tuned.
 

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Actually, when a string gets longer due to having been shot...it's refered to as CREEP. Stretch is only a temporary thing.

From BCY website...

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. Creep is a problem. It can cause the bow to go out of tune and the peep to rotate. The draw weight can increase and the draw length can increase.
 

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what kind of bow do you have? As a string builder, I can tell you first hand that one manufacturer lists specific lengths and they are actually always shorter than listed. I found this out when I first started making strings and every set that I made for this particular type of bow came in at around 6-7# less than specified weight.
So, what kind do you have?
 

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Stock Strings

I found this with my 737, shot in the string then went to set the bow to specs (#4 cam ATA 37" Brace 7") ATA came up at 37 1/8", OK a couple of twists could have done it but the Brace came up at 7 1/2".
Went for a set of aftermarket strings which I shot in then measured under tension & twisted them until they were spot on specs brace hight stayed the same but ATA increased to 37 3/8".
Is there something wrong with Hoyts spec sheets?
 

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what kind of bow do you have? As a string builder, I can tell you first hand that one manufacturer lists specific lengths and they are actually always shorter than listed. I found this out when I first started making strings and every set that I made for this particular type of bow came in at around 6-7# less than specified weight.
So, what kind do you have?
Just curious would you happen to be talking about Mathews?
 

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I found this with my 737, shot in the string then went to set the bow to specs (#4 cam ATA 37" Brace 7") ATA came up at 37 1/8", OK a couple of twists could have done it but the Brace came up at 7 1/2".
Went for a set of aftermarket strings which I shot in then measured under tension & twisted them until they were spot on specs brace hight stayed the same but ATA increased to 37 3/8".
Is there something wrong with Hoyts spec sheets?
I've found with most of our Cam & 1/2 cams that I can get A2A and brace right on by working with the rigging, but then the AMO draw length is long by approximately 1/2". That is measured per AMO specs. I've got/had 5 Hoyt Cam & 1/2 bows, and all but 1 was like this.

When adjusting the rigging on those cams, the rotation of the cam affects the A2A and the brace because of the lobe....so it is possible to actually decrease the A2A but also decrease the brace (look at how the lobe moves around the axle and what happens when you rotate) . You just need to play to get it on.
 

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Discussion Starter · #12 ·
*I would put the strings on to the lengths they specify then get some tuning knowledge if you do not have that already,I bet you will find the strings were shorter to get the higher poundage out of the bow,but when tuned properly the poundage may be lower but the bow may be closer to properly tuned.
Dude, this is the situation that I have. When I took the factory strings off, it was shorter, - string was 84.5" and cable was was at 32." Twist ratio was about 1 3/4, DW Maxed at 60#, ATA on spec at 30, Tiller even. Except for minor peep turn, everything was all good.

The messed up thing is that I ordered some custom 452x strings before thinking of measuring the factory string, and used the noted factory string specs from the manuel which call for 85" string and 32 3/8 Cable. After installing them, I tuned the bow to spec, stayed with the twist ratio of 1 3/4, and now I cant get the bow up to it max DW of 60#. It stuck on 55# with limbs cranked down.

I dont know, I told myself just be happy with a well tuned bow and live with the 5# difference in DW. At least it still shoot good and quiet.
 

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Discussion Starter · #13 ·
what kind of bow do you have? As a string builder, I can tell you first hand that one manufacturer lists specific lengths and they are actually always shorter than listed. I found this out when I first started making strings and every set that I made for this particular type of bow came in at around 6-7# less than specified weight.
So, what kind do you have?
I have an 07 Bear Instinct. Yes, the factory strings are shorter than what the factory string spec call for. The funny thing is, with factory strings everything was set according to factory spec - ATA 30, BH 7.5, Even Tiller, DW Maxed out at 60#. Except for the twist ratio which was about 2", the peep turned a little, but the bow shot great.
 

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Discussion Starter · #14 ·
Just curious would you happen to be talking about Mathews?
No, this is an older Bear bow, an 07 Bear Instinct. I once owed an 03 Martin Altitude and placed an order from som custom 452x strings and provided the string maker with the factory string specs that I had obtained from Martin. The string maker told me that because the bow was older, the strings needed to be ordered shorter. He told me that this was usually for older bows that bow companies have now started putting out the correct string specs.
 

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Discussion Starter · #15 ·
You just need to play to get it on.
I agree. I have spent hours/days twisting and untwisting the new 452x strings and cable. Since I basically have longer strings, Im not too sure what I can do. Im looking around for a bow tuning DVD or something. It could be that I havent tuned it correctly.

After setting the bow's ATA, BH, and DL to specs, and keeping the twist ratio at 1 3/4, the bow shoots pretty good. The only lost is with the bow maxed out, Im only getting 55# instead of the Max DW of 60#.
 

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You might want to check the strand count on your new strings.Some "stringmakers"like to add a strand or two(never did figure out why) and the added thickness will change the length once installed.Larger dia. takes up more space going around the cams
 

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I do not think all string specs from the factory are right. Now, this is a problem and all string makers know it. If you like the way a bow is shooting take the strings off an measure them. You will need a jig that can accurately put the strings under 100# of tension and them measure them. This would then become the new spec for you and this bow. If you want the bow in spec, but it is not twist the strings into spec and then measure them. What I like to do is measure the strings on a new bow that is in spec. If they are different than the factory written specs, I make note of it, but I build by what I know works.
 

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Dude, this is the situation that I have. When I took the factory strings off, it was shorter, - string was 84.5" and cable was was at 32." Twist ratio was about 1 3/4, DW Maxed at 60#, ATA on spec at 30, Tiller even. Except for minor peep turn, everything was all good.

The messed up thing is that I ordered some custom 452x strings before thinking of measuring the factory string, and used the noted factory string specs from the manuel which call for 85" string and 32 3/8 Cable. After installing them, I tuned the bow to spec, stayed with the twist ratio of 1 3/4, and now I cant get the bow up to it max DW of 60#. It stuck on 55# with limbs cranked down.

I dont know, I told myself just be happy with a well tuned bow and live with the 5# difference in DW. At least it still shoot good and quiet.
IGNORE twist ratio.

The only thing that matters is the length,
measured from outside edge of 1/4-inch diameter post
to outside edge of 1/4-inch diameter post.

CUSTOM strings are already sent to you at the correct length.
If you are twisting and untwisting to get a specific twist ratio,
then YOU have changed the lengths.

So,
put your custom string and cables into a stretcher,
with 1/4-inch diameter posts inside the end loops
and using an accurate spring scale,
stretch to 100 lbs of tension on the dot.

Now,
measure from the outside edge of the left metal post (hook your tape measure)
and
measur to the outside edge of the right metal post,
and get the twists adjusted until you hit factory spec
for the string length
for the buss cable length
for the control cable length.


Your custom string maker has his/her own feelings about the correct twist ratio,
and built your custom string and cables to the string maker's twist ratio.

The string and the cables should have come to use with a paper clip tying the loops together,
so the lengths were correct.
 

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I agree. I have spent hours/days twisting and untwisting the new 452x strings and cable. Since I basically have longer strings, Im not too sure what I can do. Im looking around for a bow tuning DVD or something. It could be that I havent tuned it correctly.

After setting the bow's ATA, BH, and DL to specs, and keeping the twist ratio at 1 3/4, the bow shoots pretty good. The only lost is with the bow maxed out, Im only getting 55# instead of the Max DW of 60#.
1) twisting the buss cable shorter, until you hit the 60 lbs of draw weight.

2) Now with the ATA set...tweak the control cable to get the cams into synchronization (draw stops hitting at the same time...timing dots in the correct position).

3) Now, check the draw length setting. Since your ATA was on the long side, and with the ATA set shorter to hit factory spec for draw weight...your DL will be longer than before.

4) Twist up the bowstring to hit the DL setting YOU want. Draw cycle will smooth out, as the bowstring gets shorter....the draw weight will also drop a skosh.

5) When the draw length is correct (twisted up the bowstring, as needed)...check the draw weight. If draw weight is still a skosh low, add another twist to the buss cable to hit draw weight.

6) Now, check for cam synchronization (correct cam starting rotation position...check for a draw stop on the bottom cam...if you have a draw stop up top, check this...if you only have timing dots, also check this)

7) Small adjustment to the control cable should adjust cam synchronization.


Just did this to a 75th anniversay edition Hoyt Trkon XL yesterday evening..fixed draw length Zephyr cam.
Same concepts...different brand, different cam system.

It's a riser. Top cam. Bottom cam. Buss cable...Control cable...Bowstring.
Tweak buss cable for ATA to set the draw weight.
Tweak the control cable to get draw stops / timing dots (whatever combo you have) to get the cams working together (for Hoyt, that means stops hitting at the same time...at first).
Tweak bowstring for draw length...(advance the cams..shorten bowstring for smoothness of draw cycle)....r e t a r d the cams (lengthen the bowstring) to get a sharper drop into the valley).

When cam timing (cam starting rotation position...gives YOU the draw cycle FEEL you like), then....check draw length.

Tweak the ATA shorter, to bump up (LENGTHEN) draw length sllightly..say 1/8th or so.
Tweak the ATA longer, to bump down (SHORTEN) the draw length slightly...say 1/8th or so.

When the DL is dead on...then, tweak the control cable, to get the draw stops (cam synch) to your liking...(for Hoyt...this means the top draw stop hits FIRST...and the bottom draw stop has a TINY gap).


ANY bow,
with a buss cable
with a control cable,
with a bowstring,
can be "super tuned" this way...

as long as you understand the basic concepts.


So,
if in doubt,
contact ken (baldyhunter)
and he can work with you.

He has a nice thread,
explaining cam synchronization (cam starting rotation position)
and
cam timing (cam draw stops / timing dots working together)
and...

3 EXAMPLES of draw force curves.

He has the super nice Easton Draw Force Mapper system.
 
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