Perplexing bow noise

[Stinger]

My main bow is a take down recurve that my father built about 30 years ago.  I just started shooting it again in February.  It shoots a little hard, but I can shoot it better than anything else I've tried.  Here is my problem:  My old string (not Fastflight) was getting a little worn and I wanted to have a spare all shot in prior to the season so I put a new one (3R B-50 Dacron endless loop).  It shot great the first day and I left the bow strung as usual.  The second day it still shot fine but was getting a little noisy.  On the third day as expected the string had stretched some so I twisted the string and increased the brace height and the noise went away.  15 arrows later the noise is back and the brace height is the same.  Take it down and add a few twists and it stays quiet for 20 arrows or so and then starts making a racket again.  I've done this for several days in a row now and the only time it shoots quiet is when I take it down and string it back up again.  The noise is mostly in the upper limb and is coming from the string slapping the limb; I can even get it to buzz while plucking the string.  I've tried the Hush Puppies and Bow Hush and they don't make much of a difference.  I've also looked the bow over very carefully to make sure that it isn't about to come apart - the noise is that bad. ....but, the bow is fine.  I tried a different string and it doesn't seem to make a difference.

So after shooting maybe 200 arrows on this string I believe it has to have stretched out and I'm thinking that maybe in leaving the bow strung that the string develops a "set" in the string grove on the limb that enhances the vibration at the shot and that by taking it down it changes that "set".  After 15 - 20 shots the string goes back to that "set".  I can't figure out any other reason the thing will shoot fine for a few arrows and then get noisy again.  It doesn't come on slow either.  It will be fine and then all of a sudden on the next arrow it just goes into noisy mode, and I mean it is a huge diference.  BTW, the old string (same type) has the same problem.

Any ideas on what the problem might be and how to quiet the thing would be greatly appreciated.

[macbow]

This is one of those problems that can be difficult without being there and watching.
If you had the bow hush wrapped on the string, I'm thinking that it's not string slap maybe not the string at all. I'd play with the brace height some more. Maybe it's too high? Higher brace height can be noisy.

How heavy are the arrows, light arrows require a good release to get good results. Add some weight or shoot heavier arrows to see if it changes when the noise shows up.
Ron

[PV]

Takedown buzzing is sometimes in the limb to riser connection.You can try waxing or putting a thin pad of felt between the limbs and riser.
As macbow said it is difficult to diagnose without being there.

[Stinger]

Good suggestions.  

macbow - I'll play with the brace height some more.  I think the arrows are probably heavy enough.  The bow is only 45# at my 27" draw and I get the same noise whether I shoot 510 grain wood, 570 grain fiberglass or 560 grain aluminum arrows.  I have some 200 grain tips and I'll try them to see what happens.

PV - That's an interesting idea and I have the material to try that.

[Grant Young]

Stinger, I leave the two bows I use most strung as well and I understand what you mean. All the above advice is sound, BTW, but I have to use dacron for my bows and it seems to never get beyond stretching a bit. I would advise you to measure your brace height and record it exactly the next time you have your performance and noise level "just right." The next time you shoot, measure the brace beforehand and if the string has stretched twist it back to its optimum brace ht. Macbow gave you a couple of things to look into. 9-10 grn. arrow wt. per pound usually quietens the bow down without sacrificing too much in speed or trajectory and it is possible to have your brace too high as well even though higher is usually quieter, thats only true up to a point. I have also found my release to play a large part in the bows overall performance, including noise levels. I have a tendency to let my third finger get lazy and even after forty years of shooting regularly, I occasionally have to inventory my checkpoints when things aren't quite right. Its usually me. My favorite bow is very picky about my release-the tiller is affected by that ring finger. Look at all the things mentioned but try to do it in an organized and systematic way so that you'll know exactly what (or combinations of whats) is at the bottom of the problem. Sorry this was so long.                     Grant

[Stinger]

Grant, thanks - good advice on tackling this systematically by adjusting only one thing at a time.  I'm sure part of it is me, but it is strange that when it is quiet I can pluck the string like a guitar and it is quiet.  When it is in the noisey mode, it makes a racket when I pluck it, so a poor release may only exacerbate the problem.  I have been diligent about measuring the brace height every time I shoot.  That is the perplexing part now.  The brace will be set at the last quiet setting and shoot fine and then 20 arrows later the bow is making noise yet the brace height shows the same.

[Grant Young]

Stinger- Was the bow noisy with the old string? Are you shooting with a bowquiver or any attachments? It sounds like you're going at this in a smart manner. You may try yet another bowstring just to make sure that the problem isn't there, but I would think that may be kind of unlikely. Lots of guys and some of the sponsers here offer custom strings- I use endless loop strings myself but your bow may like flemish loops better. These things are part of what makes this game so much fun to me but I know it can be frustrating. Please post the solution when you find it-I am really interested and we could all use one more possible solution in our arsenal of "fixes." Never give up,    Grant

[Stinger]

Thanks Grant - will work on it this evening - not ready to give up as the season opens here in 3 weeks and I'm not going back to wheels and I have yet to master my backup (a new Zipper).  The bow had the same issues with the old string as well.  There are no attachments on the bow save antler limb bolts, which I will remove.  I think I may have a flemish string that fits it somewhere and may give that a try as well.

[Steertalker]

Stinger,

I'm no bowyer so take what I say with a grain of salt.  You may have one limb that is weaker than the other.  When you unstring it the limbs have time to go back to there original state, but when you string it back up and shoot it in, one limb may be giving in a bit.  Try measuring the tiller of the bow immediately after stringing it up and then measure it again after the noise crops up again and see if there is a difference.

Brett

[Stinger]

Brett - interesting thought.  I was talking with my father last night and we had a similar notion, that perhaps by just switching the limbs the noise might dissipate.  Unfortunately I didn't see your response until today, but I will look at that this evening.  My dad agrees with Ron in that he doesn't think it is string slap either.

For Grant, who asked for an update:  When I finished shooting the bow Tuesday evening it was quiet. It sat overnight strung up.  The first shot out of the bow yesterday evening it is making lots of noise.  After 3 arrows I took it inside and took the antler limb bolts off and put the regular ones on.  That made no difference in the noise, so that isn't the problem.  I also tried adding points that weighed 100 gr more and that didn't make a difference either - so there goes the heavier arrow theory as well.  I then twisted the string up to 8 1/4 brace height and about half of the noise went away.  After another dozen arrows I twisted it some more to 8 1/2 and the bow was quiet for about 30 arrows at which point I had to quit shooting.  I let it sit overnight again and we will see what happens when I shoot it this evening.

Another thought is that one of the limbs might be slightly twisted causing some vibration, but I can't see any evidence of a twist.  If it makes noise this evening, I'll try switching the limbs and then maybe placing some felt between the limbs and riser.

[Steertalker]

Stinger,

Om a TD recurve I've never heard of being able to reverse the limbs, because there should be a definite upper and lower limb.  I would think they would be indexed in such a way that it would be impossible to get them reversed.  But if it is possible to reverse them then I would bet that is your problem.  Measuring the tiller would tell you that right away!

Brett

[Stinger]

Brett,

I asked my Dad about that last night.  He said that the way he made them they are interchangeable. They were never permanently marked, but I used to keep them marked.  When I refinished the entire bow this past Spring I may have inadvertently reversed them.  I'm going to check as soon as I get home.

[Steertalker]

Stinger,

I think you just solved your problem.

Brett  

[Grant Young]

Thanks for keeping us posted Stringer. I was with Brett-I don't have any personal experience with "reversible" limbs but I did have a set of Gainesville limbs for my TD back in the early eightied that were tillered "backwards"-by that I mean the greatest distance between the string and the fades was on the bottom as opposed to the top and these limbs have locator pins. They were noisey and very difficult to shoot. Owen Jeffery finally pointed out the problem to me a few years later and redrilled the locator pin holes and the problem went away. I had to mark the limbs top and bottom cause of the two holes on each limb but by then they were just extras anyway. Let us know how your experiment goes-Grant

[Stinger]

Update:  Left the bow strung Wed night and it was shooting quietly when I put it up.  Yesterday evening I measured the brace height and it had not changed.  I next checked the tiller and the bottom limb was 3/8 of an inch greater distance from the string than the top limb, so the tiller is proper (weak limb on top).  On the first shot, the bow is making noise.  3 more arrows and still lots of noise.  I then unstrung the bow and took a half turn off the string and strung it up again.  Most of the noise was gone through about 30 arrows.  After shooting the brace and tiller were unchanged.  Still perplexed.  I decided to leave the bow unstrung overnight and will see what happens this evening when I string it up and shoot it.  If it is quiet on the first few shots then I guess that will be the trick for the hunting season - just make sure I unstring it the night before I go hunting!

Next up is to try and put some felt between the limbs and the riser.  My father said that he actually used to do that (but used cork instead) on the early bows he made but he found that there was no difference in sound without them and he stopped using them.

Other than the noise, the bow shoots great - faster and more accurate than my new Zipper.

[jhansen]

Stinger,
I'm guessing the limbs are glass-backed?  On both sides?  What type of glass?  If the string isn't the culprit and the limb bolts don't loosen, then it almost has to be either the limbs or you.  This is a real head-scratcher.

John

[Steertalker]

Stinger,

Since you said the limbs were reversible I would still go ahead and reverse them and see what happens.

Brett

[PV]

If I'm reading your post correctly the tiller measurement is 3/8" larger on the bottom limb?
This is the weaker limb and usually goes on top.

[Stinger]

PV, I mis-statd it, the tiller measurement is greater on the top, so the weaker limb is on top.

John,  Yes the limbs are glass over laminate on both sides.  I have no idea what the glass is - likely whatever Herter's was selling in the late 70's.

So I left the bow unstrung Thursday night.  When I strung it up to shoot it yesterday, the brace height had increased by 1/8 inch.  ....but, it did not make a racket when I shot it.  At the end of shooting the brace height was back to where it had been the day before and it didn't get much noisier.  Funny thing is that since it wasn't making a bunch of noise and I wasn't concentrating on that my shooting improved!  I'm still going to try a felt spacer and will also try reversing the limbs to see what happens.

John, you may be right in that it just might be my bad form, but it doesn't make sense that my release would be good for 30 arrows or so and then all of a sudden be bad for the next 20 unless I'm getting tired.  But that wouldn't account for it being noisy the first thing after leaving it strung overnight and then being fine afer I take it down and put a twist in the string.

[Fletcher]

With most bows, the tiller is LESS on the bottom limb than the top.  Did you try swapping the limbs yet?