Should I increase the number of strands to reduce vibration

PLEASE HELP TO FUND ARCHERY INTERCHANGE

albatross

Supporter
Supporter
Hello All.

Riser Hoyt GMX 25".
Limbs. Kaya K3 Carbon. Long. 36lb at 70 ".

I am getting comments fellow club members regarding the noise my bow is making on releasing the arrow. They say it is noisy caused by something vibrating after the release! They have helped my with advice and assistance to try and track down the cause. They found the clicker was vibrating against the plate, so I removed it - still noisy, but not as bad. They noticed my sight was vibration when the string is 'plucked' - even though it has been tightened very hard and there is no discernible movement in the sight block or riser fitting when physically tested by hand. All stabilizers eliminated as OK.

I am currently using an 18 strand 8125 string. I understand this is a very fast string material. Would I be able to reduce the vibration by increasing the strand count (in the hope of slowing the string) say to 20 or 24? I make my own strings.

All suggestions gratefully received.

Dennis
 

albatross

Supporter
Supporter
Yes I have gone through the range of brace heights 8 3/4" to 9 1/2" and settled on 9 1/8" as giving the best groups. The tiller is currently at 4mm (sorry for the mixed units).

Question. How would tiller affect noise/vibration?

Dennis
 

Hudzi93

New member
If the limbs have different amounts of energy in them on returning back to their neutral position after release, there will be added noise and vibration.
 
Increasing string count wouldn't really help I'd have thought. Do you think there is a vibration in the sight or the overall bow thats noisy on release?

If you want to find out, stick some string silencers on it (a pom pom top and bottom of your string, google it) If that quitens it down even a fraction, then its likely your tiller/brace/arrow tuning is out. If it doesn't make a difference its your sight, try padding it with a piece of plaster where it meets the block to stop metal on metal contact, and check all the screws, I know an archer whose sight thread didnt extend far enough so it rattled and would allow his sight to slip.
 

Mufti

Member
Take everything off your bow that will come off.
If the rattle/buzz sound disappears then it is your equipment, if not then your setup needs looking at.
Can you feel the limbs vibrating after the shot?
Can your fellow archers see the limb tips shaking after the shot?

Adjust the tiller . . . and then readjust the brace height . . . and then readjust the nocking point position . . .

rinse and repeat as necessary.
 

Mark31121

Member
Ironman
Is your clicker plate loose? I know someone that had this and it took ages to find...

Try shooting with absolutly nothing on the bow, keeping your anchor point the same etc (so close range if you're unsure that you'll hit), that will give you an indication if it's something loose, if it is then put things back on one by one until you find the culprit.

If not then look at your BH again and your tiller and that your limbs are sitting in the pocket correctly and make sure that you're arrows are heavy enough.
 

backinblack

Active member
Hi Albatross,

There's been a thread on the physics of this recently with contributions from cleverer persons than me: http://www.archeryinterchange.com/f37/tiller-difference-why-191133/

Essentially you want the two limbs to finish their power strokes at the same time. If they do you get (for want of a better way of explaining it but please feel free to choose your illustrative noise of preference ) a bang as opposed to a ba-bang.

If you have a tinker with the tiller, you should get to a quiet spot but it where it is depends on the limbs as some have a built in tiller. At this point if you turn the bow string upwards and twang the string near the end of the limb the vibrations should stop fairly quickly. It's finger in the air stuff but if you have an idea of the starting point you should be able to improve the situation. As stated above you will then need to revisit nocking point and bracing height.

If this doesn't help then alternatives would be a heavier arrow or maybe a slightly less aggressive string material. I've found BCY 450+ quietens a bow down nicely but there's some sacrifice in terms of cast. An 18 strand 8125 string is by no means short on strands and if you go with more you will potentially have nock fit issues.

Or again if all else fails, you could have a look at limbsavers as a last result to absorb some of the vibrations (this assumes you already use a stabiliser set and maybe short rods also, if only a stab set, then go short rod first).

Hope that helps,
Backinblack
 

albatross

Supporter
Supporter
Hi Albatross,

There's been a thread on the physics of this recently with contributions from cleverer persons than me:
@backinblack
Any idea of the whereabouts of that thread?

Thank you all for your suggestions. I am reading and noting the other suggestions.

I was wondering if the number of twists in a string could cause it. My string 66 3/4" (70" bow) only has 15 twists in it to get it to my current brace height.

Dennis.
 

backinblack

Active member
Hi Albatross,

Linked it now, sorry hit the reply button rather than paste. Added additional comments by way of edit above.

Best regards,
Backinblack
 

ThomVis

Member
What physical weight are your arrows, and have you tried heavier ones? Too light of an arrow will make a bow noisy too.
 

albatross

Supporter
Supporter
Hi Albatross,

Linked it now, sorry hit the reply button rather than paste. Added additional comments by way of edit above.

Best regards,
Backinblack
Just read it. Very interesting. Thanks for the link.

@ThomVis What physical weight are your arrows, and have you tried heavier ones? Too light of an arrow will make a bow noisy too.

They are Win&Win challenger 100% carbon arrows for my draw weight. But I will try some aluminium ones just to see the difference.

Dennis

Edit: just did some more brace height tests with the 'bare Bow'. result in same brace height. HOWEVER. Then I inserted a strip of first aid plaster between the limbs and the end of the riser where the limb exits as they were rubbing (marks on limb faces). Although I wear hearing aids there does now seem to be a difference (doubtless someone will comment tomorrow night at the club).

@Mufti. Is it possible that the vibrations from the limbs after the release (they are vibrating as I have seen them) is setting up some form of resonance within the riser and the riser is acting as a 'sound box'?

Dennis
 

albatross

Supporter
Supporter
Exactly so and it will give you arm ache too!
My bow arm does ache after a while! I thought it was the weight of the bow causing fatigue, now I am rethinking it! I have a lot of pressure on the top of my bow hand thumb knuckle from the underside of the grip, which can be painful after a while. Could this be another sign that the tiller needs increasing - in order to get more resistance to bending the lower limb and thereby lower the 'pressure position' of the grip?

Dennis
 
Heyhey! The sticking plaster comes in useful again!

Resonance is more than possible yeah, good thought... That'd also do some weird things to your arrow flight if I'm right, if so, then in theory anything that changes the characteristic of either limb or riser should stop them peaking at the resonant frequency, rubber dampers for your limbs are available, but im almost positive they wouldnt do the job. A change in stabiliser/long rod weight/length/rigidity will very rapidly change the frequency characteristics of the system.

Actually, a possible easier solution would be adding/removing twists from the string, this would change the limb behaviour and may drop them from the very fine peak of high resonance frequencies.
 
If you've got time, this will do it.

Take all the attachments of the bow, string it.

Attach a SINGLE short rod WITHOUT weight to the bow very loosely screwing it in

Hang the bow from a fixed point and tap it, it will vibrate, repeat, tightening or loosening the rod to achieve the quickest drop in vibration.

Fix this characteristic (masking tape/allen key/superglue/whatever you're comfortable with).

Attach the weight and repeat again.

Repeat, adding long rods, short rods, weights, sights, everything.


This will have your bow tuned to its lowest vibration level.


Do this after adding/subtracting string twists to see if it gets better.
 

albatross

Supporter
Supporter
Heyhey! The sticking plaster comes in useful again!

Actually, a possible easier solution would be adding/removing twists from the string, this would change the limb behaviour and may drop them from the very fine peak of high resonance frequencies.
As I write this reply I am in the midst of making a slightly longer string (70" instead of 66 3/4") which will require more twists (not too many) to get to the brace height I need. I have seen on various archery forums that the ideal number of twists is about 20. So that is what I aimed for, but I may have to settle for 30ish to cure the problem.

Dennis
 
Hey, mine vary from 1 every 6inch to 1 every inch.. haha

Making a new string is a possible solution to the problem, if you've got the equipment for it, perfect.

I'd try adding and/or removing say 5 twists from your existing string, different length, different string angle, different tension, different behaviour.
 

albatross

Supporter
Supporter
Look what I just found on th BCY website!

Question: Is it a fact that the lower the number of strands, the faster the arrow?
Answer: Yes on most bows but not all, and of course with today"s extremely strong materials, a lower number of strands can normally be used safely. Of course it is important to be sure that the center serving is built up to allow a good nock fit when the number of string strands is reduced. Note also that at a certain point not too far below the manufacturer"s recommended number of strands, it is quite likely that the archer will notice an increase in vibration directly after release because there is not enough mass in the string to absorb the "elastic energy" that occurs when the arrow is released.

Note that HMPE products like Dyneema[SUP]?[/SUP] and Spectra are prone to creep more if fewer strands are used. "Elevated temperatures and higher draw weights increase this problem."

Dennis
 
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