handshock and string vibration?

[willie]

About 10 years ago I built a 60# 69" osage elb. The tiller was as perfect as I have ever gotten one. The first shot out of the bow my hand felt like it was broken. After about 5 shots I couldn't use my hand for a week. I took it home and dropped it down to 50# making the tiller more elyptical and the shock all but went away.

I am guessing that not all that much wood was removed, to be able to blame "excess mass" for the initial cause.
nor would think that uneven tiller was the cause.

something about how the limb vibrates maybe?

[Strichev]

If mass alone is to blame, wouldn't those Viking bows be absolute nightmares to shoot?

[Jesse]

I think what badger is saying about tiller makes sense. A sraight bow with a round tiller puts all the force in the handle. Having an eliptical tiller or a  reflex deflex design disperses it through the limb more.
  Like Dell mentioned also the string can affect it also. I think bows with dacron strings seem more shocky.

[Badger]

   One thing you might see a lot of disagreement on even among the veterans is on limb timing. I don't think limb timing has anything to do with the tips stopping at the same time. I think limb timing has to do with how a limb straightens back out. Ideally it would straighten from near the handle and work out to the tips. If the tips hit before the inner limb is straight the timing is off. The tips can easily get ahead of the inner limbs. Keeping the outer limb stiffer with even stiffer tip areas helps to avoid this. 

[Danzn Bar]

Hummm....just trying to visualize the tip hitting or ending before the inner limb does... would that be the result of a bad tiller?
DBar

[willie]

I think limb timing has to do with how a limb straightens back out. Ideally it would straighten from near the handle and work out to the tips

Good point Steve. So, short of some kind of photographic/scientific analysis, a bow that is damp in the hand may be more efficient, at least when it comes to vibration?  Can you comment about the shockiness/vibration qualities of a bow proven for flight  shooting?

[PatM]

I don't think the limb timing theory is the reason either.  Nor tip mass.

[Danzn Bar]

OK PatM I'll bite ...... what do you think causes it??
DBar

[Badger]

I think limb timing has to do with how a limb straightens back out. Ideally it would straighten from near the handle and work out to the tips

Good point Steve. So, short of some kind of photographic/scientific analysis, a bow that is damp in the hand may be more efficient, at least when it comes to vibration?  Can you comment about the shockiness/vibration qualities of a bow proven for flight  shooting?

  Willie we are shooting arrows as light as 150 grains with no handshock at all. The biggest single loss of energy in all types of bows is limb vibration, it can't be avoided 100% but it can be tillered in such a way that it is minimized and in sinc.

[Jesse]

Maybe timing was the wrong word. I dont know if the limbs can reach home at different times or not. I was refering to the tillering between top and bottom limb being identical based on tracing lines as opposed to going by eye. I think if they are off they can be imbalanced and fight eachother after they hit home causing handshock. At the least a slower bow.

[Badger]

Maybe timing was the wrong word. I dont know if the limbs can reach home at different times or not. I was refering to the tillering between top and bottom limb being identical based on tracing lines as opposed to going by eye. I think if they are off they can be imbalanced and fight eachother after they hit home causing handshock. At the least a slower bow.

  Jesse, I would agree with that, I think the limbs need to match also. That could be a major reason for shock in some bows.

[Tuomo]

What is "handshock"? Everybody knows it in practise but how it is defined physically? Is it forward (in direction of the arrow) momentum of the bow, which can be felt? See this video:

https://www.youtube.com/watch?v=xGgWZYny9RM

As you can see, the bow is flying forward, in the direction of arrow (if there would be an arrow...). Try this and every bow is flying forward.

Is the root cause momentum of the kinetic energy of bow after arrow has leaved the bow? Momentum is vector quantity and it has direction. A bow has some kinetic energy (bows potential energy minus arrow's kinetic energy minus hysteresis minus other losses), and momentum, which has direction.  So, it would be possible to measure the real handshock with some kind of force sensor, which is put in front of the bow.

Regarding Steve's experience that more elliptical bow has less handshock is valid, because there is less mass (of the bow) which is moving forward. Very elliptical tillered bow has only tiny tips, which are moving forward -> less forward moving mass, i.e. momentum to direction of the arrow.

Note, that tiller difference or limb imbalance has quite minor effect - the bow is staying upright, neither of the limbs are not leaning forward or backward. The bow is flying straight forward.

Easy way to see objectively, how much a certain bow has handshock: Shoot it with open grip and see how far the bow flies... 

[AndrewS]

...

Easy way to see objectively, how much a certain bow has handshock: Shoot it with open grip and see how far the bow flies... 

 

A good explanation of handshock is in the book of Stim Willcox "Art of .....".

[BowEd]

Vibration or kick in the handle upon release is unpleasant.I'm sure as stated by others on here of the different reasons.The lightest arrows I shoot are usually no less than 8gpp arrows and if I don't feel anything it's good to me but normally I usually always shoot at least 10 gpp arrows.

[George Tsoukalas]

Limb timing and tiller are important contributing factors to me. Timing and tiller are not the same.
Also, limb mass. Too much mass for the design will add shock.
Yes, indeed, a bow that bends TOO much in the handle will shock.
Jawge