Brace height effect on arrow spine & tune

[spidermonkey]

When I recall WAAY back when I first started shootin traditional, it was for the SIMPLICITY of it... THANKS a lot Scott! Good Huntin, and God Bless, Rusty

[SwampRabbit]

When within an acceptable spine match to the bow, and assuming a decent release/loose, the shaft will flex three times during the power stroke.

First flex - Occurs at release/loose of the fingers from the string, and forces the shaft inward toward the strike plate. This flex is initiated by a combination of the roll of the string from the fingers, and the forward force applied to the tail of the arrow.

Second flex - Occurs during mid power stroke, and is simply recovery from the first flex, and springs the shaft outward, and away from the strike plate.

Third flex - Is a recovery from the second flex, and once again is forcing the shaft inward toward the strike plate. This flex occurs right at the point where the arrow is exiting the string. The lower the brace height is at this point, the closer the proximity of the shaft is to that of the bow/strike plate during the pass, thus the stiffer the shaft the more likely it, and/or the fletching will make contact at this point.

Side note to this point:
Aside from dragging the string & limbs forward creating shock, and vibration, one of the reasons why nocks that are to tight create arrow flight problems is they straighten out the 3rd flex, and jerk the arrow back into contact with the bow.

Rick

Agreed, but the relationship between braceheight and the riser doesn't affect the launch angle as your picture shows or suggests. Adjusting brace height doesn't have that impact. The shaft should never touch the rest again after it comes off of it when the shaft rebounds from the initial flex... or, as you know, you get kicking. There is no soft landing on a riser



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[Junkers88]

When I recall WAAY back when I first started shootin traditional, it was for the SIMPLICITY of it... THANKS a lot Scott! Good Huntin, and God Bless, Rusty

No **** right!? I'm more lost now.

Richard

[jerp]

Thanks a lot guys. Just when I have pretty much broken my habit of overthinking/over-tinkering you guys give me something else to think about/tinker with.

[RickBarbee]

Agreed, but the relationship between braceheight and the riser doesn't affect the launch angle as your picture shows or suggests. Adjusting brace height doesn't have that impact. The shaft should never touch the rest again after it comes off of it when the shaft rebounds from the initial flex... or, as you know, you get kicking. There is no soft landing on a riser



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You are absolutely correct, and now I am scratching my head some.
That's a good thing.

As I stated though, the picture is an overstatement (pretty extreme overstatement).

The fact remains however, that the lower the brace height the lower the spine requirement will normally be, and I can now see, that the relevancy could only come at return to brace during the shot, and not at resting brace. This is why I love discussing these things.

That's not my picture by the way.
Came from a book called "Shooting the stickbow" by Anthony Camera.

Rick

[RickBarbee]

OK guys.

I went straight to the source - Tony Camera, author of "Shooting The Stickbow" with the following question:

How could this diagram be relevant at resting brace height?
The arrow is, or should be clear of all contact long before the arrow returns to this spot during the shot.

His reply:
"Rick -

It's relevant because the string has to get to the "resting" brace height from the anchored position. The lower brace height has a similar effect as a taller rest (distance from center) just BEFORE the arrow disengages - that's due to the angle off at that point. The fact the arrow is no longer on the rest is irrelevant, because it's own inertia is still a factor.

And no, I didn't draw that picture to scale "

[shortstroke 91]

For anyone who doesn't believe this method is correct try this. Twist your string up and add about an inch to your current brace height. Right handed shooters will impact right (lefties, left) now untwist and drop your string an inch lower than your normal brace height and notice the arrow impacts left for right handed shooters. This is all assuming your arrows are at least close to correct in the first place.
If nothing else it makes for micro tuning to get the arrow to impact exactly where you are looking.

Thanks Rick.

[SwampRabbit]

OK guys.

I went straight to the source - Tony Camera, author of "Shooting The Stickbow" with the following question:

How could this diagram be relevant at resting brace height?
The arrow is, or should be clear of all contact long before the arrow returns to this spot during the shot.

His reply:
"Rick -

It's relevant because the string has to get to the "resting" brace height from the anchored position. The lower brace height has a similar effect as a taller rest (distance from center) just BEFORE the arrow disengages - that's due to the angle off at that point. The fact the arrow is no longer on the rest is irrelevant, because it's own inertia is still a factor.

And no, I didn't draw that picture to scale "

Funny, as I was walking last night, I had typed up a response that pretty much stated "if I had to guess, it would have more to do with string path - ie the string has a compressed path to get from point A to point B and the angles will be different due to the fact that the same, if not a little more, force is being applied over a compressed string path."

With that being said... I would hypothesize that the impact of BH likely has more to do with the steering and force vectors placed on it by the string over the string path than it has anything to do with angles of the arrow relative to the strike plate at rest. And beyond that, there are likely just a bunch of little "in the noise" differences that add up to play a bigger role. For instance, the increase in draw weight when you up the BH is very small, but it is a small contributing factor that has no other factors that negate it and likely a bunch of other factors that build off of it.

Again, just my opinion that somebody is explaining a proven relationship using a causality that isn't an actual factor.

[SwampRabbit]

... and with that... I am gonna check out on this conversation. Probably shouldn't have even dived in because it can ruin it for me. Sometimes I like to not think too much about certain things.

[DRT]

My brain hurt just reading that.

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[RickBarbee]

When my brain is hurting it means I "might" be learning something.
I love learning, and very much appreciate everyone's input to these type discussions.

Rick

[SwampRabbit]

They are definitely fun discussions as long as you have the right attitude about it and it isn t about proving people right/wrong. I knew that was tge case here so I weighed in.

I am a whiteboard talker though so sometimes the forums make it hard to communicate my points.

My role as an engineer, I am expected to know and understand things. In my field, I am expected to dive deep into various areas and close the knowledge gap for our company AND innovate based off my knowledge of how stuff works.

There is so many things to learn and not enough time to learn them all, and I have learned that I need to ask myself "to what end" do I need to keep digging deeper to satisfy my desire to understand vs just wanting to enjoy an activity... the struggle is real

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[spidermonkey]

Well Scott, I'm purty sure you know I was just jackin with ya (as usual)! But , to your point, I also have to do a lot of in depth ciphering at my job as well, and I'm wired that way... BIGTIME! But, I usually don't take that approach with my bow shootin. For some reason, I've always been able to not over-analyze that part of my life. Don't get me wrong, I will not tolerate my arrows to not be flying true, my bow shootin loud, some strange noise, etc. Funny thing is, I either know, have used, or at least heard of a lot of these various "tuning" methods over the years. I guess I just choose to keep it as absolutely simple as I can, I mean we are talkin bout me here! Like I mentioned earlier, that is PART of what drew me to traditional years ago... Simplicity. As long as the center of my nock follows the center of my broadhead/field tip, I can work with that! And... Part of my job is figuring out how to make something work that the engineer(s) guarantees is supposed to work "according to the drawing"... Sorry Scott, couldn't resist! Good Huntin, and God Bless, Rusty

[KenWood]

Aside from the tech, I start my tuning process with a full length arrow( I can't cut much at 30" of draw). Weak or stiff I find the point where my bow is the most quiet, the least hand shock, and just feels the right. Then I'll add weight or cut what I need to getting a good flying arrow. Is there a measurement I need to take past that to find the optimum brace? I have never adjusted brace to make an arrow work. It's always the other way around. Not saying that I'm right because lord knows I don't know it all.

[DRT]

I like the discussion but I won't say it all makes perfect sense or is something I know how to apply.

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