New string and tuning woes

[olddogrib]

Can a new string cause arrows to shoot noticeably stiff, indicating a loss of cast? I've seen minor tweaking required from string changes that could be tuned out with an additional 25 or so grains of point weight.  Often that went away as the string stretched in.  The new string is a D97, 10 strand plus 8 in the loops for a 48# bow.  Unfortuately, I don't know the composition of the old one.  I weighed them and do know the new one is 50 grains heavier (186 vs. 136 grains). Some of that may be wax weight, but would that be enough to show a difference?  Nock fit is comparable on both, silencers are both wool yarn. The only other difference is the old one does not have padded loops, but I've been told by a bowyer that as long as I didn't go below 12 strands, padding the loops for recurve limbs wasn't a big deal.  Also, I really don't want to increase point weight, so if the physical weight is the issue, what's my best chance of getting a lighter string, 450 Premium maybe? I'm a stickler for nock fit(X nocks) and don't tolerate serving slippage well at all.

[Overspined]

Check out the nock point and the brace ht. There really isn't a reason D97 should shoot any different than any other synthetic ff string. Weight of the string shouldn't change a lot, especially w/ the padding. Padding shouldn't change anything. You could always buy a 450 and check.

[mrpenguin]

If the string is a faster material than before or fewer strands than before, it will speed up... the opposite is also true.  As long as bh, np, etc... are all the same, you can try taking out your silencers to see if that corrects it.  If so, the string is a slower and you may need to retune the bow to the arrows.  You can try to adjust bh to speed it up a bit and see if that trims out the arrow flight as well.

[larry]

are your silencers also heavier on the new string? if they are a little heavier and your string is a little heavier and if you were right on the border with spine..it ight be enough to slow them down and make them stiff?

[Don Stokes]

Adding 50 grains to your string weight definitely can make a difference.

[JC]

Originally posted by Don Stokes:
Adding 50 grains to your string weight definitely can make a difference.

Yep, I think Don hit it.  50 grains at the string is a LOT and in my opinion would surely effect arrow tune.

[SERGIO VENNERI]

Probably Nocks too tight on the string serving!

[LBR]

The extra 50 grains is from padded loops vs. non padded loops, which should make little to no difference in performance.  

I just weighed the extra strands, and even with less than usual wax they weighed 20 grains (10 strands--half the padding).

My thoughts are the string just isn't shot in yet, but that's just a guess.  I'd like to find out what the deal is here myself, as I made the string in question.

Chad

[Don Baker]

Agree with Chad-I'll bet it is a brace height and maybe nocks too tight issue.
Don

[JC]

If the weight is indeed from the loops (and if he got the string from you Chad I'm sure you'd know) then it ain't the extra 50 grains. That would only matter if it were nearer to the string center. With finicky bows I've seen tuning differences with as little as 20-30 grains near the center (serving and nocks) but I doubt now that's the case here.

I read that he said nocks were comparable on both so I just assumed that if he was getting good flight on the first string nock tension shouldn't be the cause of problematic flight on the second.

Now that Chad mentions it, string stretch/brace sounds like a possible winner to me.

[olddogrib]

Nock point, brace, silencers, and nock tightness are all subjectively comparable, as I have no other way to measure such things. I was not naming the maker, as there is certainly nothing "wrong" with the string.  It is of high quality and exactly what I asked for.  It is heavily waxed (a good thing) and my intent was merely to determine if the physical weight difference and/or a new string stretching in would explain the effects I'm seeing. Since he has named himself, I'll try to do an update as to whether the change is temporary. For whatever it's worth, a friend who's a top-notch trad tournament archer, said  a lot of folks would be shocked if they chrono'ed their bows immediately after waxing their strings and saw how much difference it temporarily makes, with all else being equal! Nobody's suggesting we start blowing up bows with a ban on string wax here.  It's just that, like many things, there's usually more going on than appears at first glance.  I had a perpetually bruised forehead from beating it against the wall in ignorance for years after I first got into this game. That's the beauty of this website, quicker recovery time!

[LBR]

I appreciate that ODR.  I really appreciate you contacting me first, and giving me a chance to try and figure out the problem, and keeping us updated on it.

Shoot, if I goof up, I want to know about it--hard to fix it if I don't ever know.  If I can't figure it out, I'll start asking other folks who might know something I don't.

Chad

[Don Stokes]

I use Chad's strings too, and I've been very pleased with them. If the additional weight is in the loops, then that's not the problem. Chad knows his business.

[olddogrib]

No problem Chad, just didn't want this post to get headed "off in the bushes"!  On a tip I left the string in the sun in my black truck on a towel today and it lost 5 grains, I can only attribute to wax melting out of it.  I now know that D97 is physically heavier than 8125.  I don't understand why where mass is added to a string would make any difference.  It would seem the limbs are having to overcome the weight of the string and the weight of the arrow upon release.  There was an article in TBM recently that documented the loss of performance with heavier string silencers.  Any physics folks want to "weigh in" here?  I get lost when you get past the "pi are round, Bunny Bread are square" thing!  And lastly, I got some bad advice.  The bowyer that made my bows said don't use non-padded loops on his recurves, regardless of the number of strands.

[Don Stokes]

ODR, it's a matter of degree. Yes, weight added anywhere has to be taken into consideration, but weight added in the string has other effects. A heavier string has to be braced higher, for one thing, to keep it from slapping your wrist. A heavier string also tends to create more lateral motion during the dynamics of the shot, which affects tuning too. When the string rolls off your fingers, it has to come back into alignment with the center of the bow through a series of oscillations. A heavier string "dampens" more slowly. String silencers affect these same things, and the nearer they are to the center of the string, and the heavier they are, the more effect they have on tuning.

I'm not a physicist, but I did stay in a Holiday Inn Express once upon a time. Found it to be a bit pricey.    

[olddogrib]

One other thing I thought was unusual. After leaving the string in a hot vehicle all day, I fully expected it to expand and that I would have to add some twist when I put it back on the bow.  I was surprised to find my brace height had increased by almost an inch.  Do synthetics contract when hot?

[LBR]

Any string material stretches/creeps when exposed to heat.  How much depends on how much heat, how long the exposure is, number of strands in the string, draw weight, type material, etc.  That string had approx. 300# of torque put on it after it was made, but the heat will get any of them.

Chad

[olddogrib]

Chad,
My brace height had increased, not decreased.  That means for whatever reason the string was temporarily shorter when I put it back on than when it was removed.  I actualy had to untwist it about ten rounds to return to my brace.  After shooting about 20 arrows, I was below brace and had to add about 5 twists back.

[LBR]

When you unstring, it will contract some.  Again, how much depends on bascially the same variables.  Dacron is the worst, but they all do it some.  That's one of the main reasons I like to leave my bow strung all the time (except my selfbows).

Chad

[Don Stokes]

I keep mine strung too, EXCEPT when it will be in a hot vehicle. The bow can fail if it overheats while strung. I'm sure y'all knew that...