Going round so far you end up back where you started

[LineCutter]

I've done this a few times, but don't recall it being mentioned explicitly elsewhere... I set out to tune my bow & end up with the walkback looking fine, but with the tune at the second harmonic i.e. good looses go fine, but boy is it temperamental with less than prefection!

I did this the other day - got a perfect walkback, but lousy arrow flight at real target distances. I've taken quite a lot of spring pressure off & now have a much better tune & still a straight walkback (there are pics in my journal if you're fascinated).

Am I right in thinking that this is a harmonics thing? (& why doesn't this seem to be talked about commonly?)

[Jerry Tee]

It is possible to get a good tune indication with the button doing far more than it should to keep things on the straight and level so to speak. With the conpounds that I have it is possible to alter the button and trim the weight of the limbs to get the bow tuned again. I think I have found a good middle of the range tension of the button spring and I have set up the peak draw weight to get a good bear shaft placement . I hope that by doing this I will be operating the button in the middle of its' range and there fore get a more tolerant set up. Time will tell.

[geoffretired]

Interesting ideas Linecutter.
Perhaps it is rarely talked about because it has not been noticed by many people.
I don't understand the "Harmonics thing", in relation to archery that is.
Is there some information about that somewhere?
If I've understood correctly, your arrows do match the bow and can fly well(on one spring setting) while giving good walk back results. With more pressure on the spring you keep good walk back results but create poor flight. Is this where you think the harmonics come in?
Should this information be added to the tuning guides so that others don't end up going down the wrong road? Is there an implication that good flight needs to be found first and the walkback fine tunes that so the flight path is generally straight too?

[LineCutter]

I've assumed (& I'm sure that Joe will refine this for me) that the tuning of the arrows to the bow is a matter of getting the flexing of the arrow to match the pressure that it exerts on the bow/button.
The walkback then demonstrates how far off this point you are (the arrows come out at an angle, which shows up more with increasing distance).
BUT... with the flexing being an oscillation there must be more than one point at which the arrow is moving in the same direction w.r.t. the bow & therefore gives the same angle of deflection.
The harmonics idea just says that for every one of these that you find, beyond the first (ideal) one, the margin for error decreases. (Think of sine waves, with the frequency doubling (& the size of the trough halving) for each extra harmonic). I'll see if I can find a picture, if you don't see what I'm saying.

[geoffretired]

Linecutter,I think I understand what you are saying but I'm not sure that we both have the same ideas on tuning.
I see the arrow flex/frequency as fixed by the arrow itself. Moving the button in or out may change the amount of flex but the frequency will remain the same. Getting an arrow to clear the bow nicely is to do with getting the tail bent away from the riser/rest as it passes.
If the spine is slightly wrong for the bow, it may need to be shot with the rest further out in order to gain clearance.I've always assumed that stiff arrows fly further away from the bow for that reason. Flying off to the left will show on the walkback as a slope to the left, as you already know.(assuming a right hander)
If the arrow is well away from ideal, it may need the button to be so far out that it clears, but flies badly, as it is being launched at an angle that produces oscillations caused by the fletchings dragging the back into line and overshooting.
This is only how I think. If I'm wrong then the sooner someone like Joe gets involved the better cause I don't like not knowing.
It's an interesting idea all the same.

[Jerry Tee]

It is not so much an oscillation as far the interaction between the arrow and the bow is concerned. The arrow will continue to oscillate all the way to the target but that can be discounted because we have no way of affecting it. What is vital is alignment of the nodes of the arrow and tuning the bow to get the broadest band of loose condition allowing this to happen is what you are aiming for. by the time the arrow clears the riser it will have completed about one cycle of oscillation. There arn't going to be any harmonics because that would mean that there would have to be more than one set of nodes on the arrow and so far Easton have not found any more than just two node points.

[LineCutter]

I suspect that we're all saying the same thing, both about the effect & the concept involved. We're just using slightly different words.

The harmonics thing was not meant to be literal in terms of the number of arrow nodes, but fits the perceived effect - there is a best position, with a broader tolerance of less than ideal looses, then at least one other position where the bow-button-shaft interaction will allow a straight walkback, but little tolerance for poor looses.

I can, & have, demonstrated to my satisfaction that it exists & have done on several occasions. I just wish I hadn't.

[geoffretired]

This is getting more interesting!
When you demonstrate the two positions, what is the difference between them? I think you said let off the spring pressure, but do you change the centre shot setting or not? Have I got this right, the weaker setting of the spring gives good arrow flight and good walk back results? When you stiffen the spring, is there a specific setting that gives good walk back? Weaker and stiffer than that, give poor walk back?

[Jerry Tee]

Sorry I thought you meant a literal harmonic.( Gone away to think (ouch))

[LineCutter]

Originally Posted by geoffretired

This is getting more interesting!
When you demonstrate the two positions, what is the difference between them? I think you said let off the spring pressure, but do you change the centre shot setting or not?

The difference this time was about 1/4 turn of button position & 3-4 turns of button pressure. I tend not to count, but having got a meta-stable tune I go right back to basics & start again rather than risk it. Last night was an exception in that I was already pretty close on the first attempt (Largely a return to my previous setting).

Originally Posted by geoffretired

Have I got this right, the weaker setting of the spring gives good arrow flight and good walk back results? When you stiffen the spring, is there a specific setting that gives good walk back? Weaker and stiffer than that, give poor walk back?

Probably - there is certainly a stiffer setting that is compatible with a straight walkback, although I'd guess that the group sizes would be larger if I'd looked. FWIW the first tune was if anything suggestive of the button being slightly soft for what was needed!