Trad Gang
Main Boards => PowWow => Topic started by: NothingHappenedToday on January 18, 2016, 10:15:00 PM
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Hi all, I just read Byron Ferguson's "Become the Arrow." In it, he recommends decreasing brace height for stiff arrows, and increasing it for weak arrows. This is the exact opposite of everything I've read and seen online and in books. Seeing as how he's such an accurate shot, is he right and everyone else is wrong? Thoughts?
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Byron's right. And it coincides with most everything I've read. Reducing the brace height lengthens the power stroke, increasing it reduces the power stroke. Small changes in brace height are really just for final tuning though. They don't make a big difference, but the direction of difference is what Byron suggests.
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My personal experience mirrors that of other things you've read. Symptoms of a stiff arrow are resolved by increasing brace height, symptoms of a weak arrow are resolved by decreasing brace... and very slight changes that don't much affect length of the power stroke can make quite a lot of difference.
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opposite
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I'll I have read the book... If indeed he states that I will have to agree to disagree.
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Caughtanhobble it's on page 46
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First off, I am no expert but what Byron Ferguson says seems correct to me. A stiff arrow will be weakened slightly by a longer power stroke which means a reduced brace height. Increasing the brace height would reduce the power stroke and make a weak arrow shaft seem slightly stiffer. Again, I am not an expert just the way my brain thinks.
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I should elaborate. As I noted, these differences are very small. Increasing the brace height increases the poundage, but it reduces the power stroke. Which has the greater effect is probably determined by bow design, and it may be a wash.
Likewise, lowering the brace height decreases the poundage, but increases the power stroke. Again it may be a wash. Would have to compare force draw curves for the various adjustments on the same bow to know for certain.
Think about it. A change in brace height of 1/8 inch might increase or decrease the draw weight by 1/4# or so. That's a very small difference. That's not a difference that most are going to notice, though those who tune to the nth degree say they can tell the difference.
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Please explain how changing brace height changes the poundage of a bow? I see it changes the preload of the limbs, but at a given draw length the limbs are loaded the same regardless of brace height. It is just the power stroke that is changed. And as you said, it is a minor change. Just trying to learn the physics of the bow here.
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Ok after thinking I understand the poundage change (I think). Basically, changing the brace height changes the string length. A shorter string increases brace height but also loads the limbs more at the given draw length. So the draw wight is increased, but the power stroke is decreased. Which has greater significance? This is where I need a chrono to do some testing.
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The way I see it is all about the angle of the arrows approach. The shorter the brace height the arrow is getting to the shelf faster and heading to the left sooner (right hand shooter). Vise versa for the longer brace height... I hope this makes some sense. :)
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Please stop. I thought I had this tuning stuff figgered out and now this. Oy vay! :banghead:
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IMHO...Mr. Ferguson is correct
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Ok, so.... if the tuning of your bow isn't quite right, add or remove twists to your string, which will change the brace height and several other factors about the bow's physics.
That can either change or not change something and everything might be good... or not so good... or we can't tell anyway.
I got it ! :dunno:
ChuckC
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Originally posted by highlow:
Please stop. I thought I had this tuning stuff figgered out and now this. Oy vay! :banghead:
That's how I feel- I knew how to coax my arrows to fly right until about 2 minutes ago.
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Why is a Bow with 45#@28" slower than with 45#@31"
Because the arrow is accelerated longer at 31".
That means you can shoot stiffer arrows at 31".
OK, this difference is about 3" and the difference by tuning the brace heigh is maybe 0,5" but it also has an impact!
Another comparison.
On my bow 400 spine works perfekt at 31".
When I'm shooting 360 spine the arrow always went to the left because he is to stiff but... when I'm drawing a littlebit more the 31" the arrow went right straigt as he should.
I'm conform with Byron.
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actually the longer draw gives you a HIGHER DRAW WEIGHT.....that is the primary reason over drawing increases arrow speed...all things being equal.
for a hunter with consistent draw...the lower braceheight will provide a LONGER power stroke pushing arrow...
two different things...draw length affect vs brace height affect.
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Part of the problem here is nomenclature and use of language. If someone says, "reducing the brace height stiffens the arrow," do they mean that reducing the brace height makes a given arrow shoot as if it had a stiffer spine, or do they mean that reducing the brace height allows you to shoot a stiffer arrow than you could use at the higher brace height?
Same with center shot. I think I have this one figured out: you need to use an arrow with weaker spine for bows not cut to center shot. But I've read things that are vague enough to be interpreted either way.
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Originally posted by Brock:
actually the longer draw gives you a HIGHER DRAW WEIGHT.....that is the primary reason over drawing increases arrow speed...all things being equal.
for a hunter with consistent draw...the lower braceheight will provide a LONGER power stroke pushing arrow...
two different things...draw length affect vs brace height affect.
I have to disagree with your first statement. For a given draw length, decreasing brace height results in a lower draw weight, because the bow is less flexed at full draw. To take it to extremes, imagine drawing a bow strung with the string tight, but not flexing the bow, which would be the ultimate in low brace height. By the time you got the bow to full draw, the bow might only be flexed to a normal brace height, so would be lower poundage than a bow that starts its draw at normal brace height.
What lower brace height does is increase the power stroke, as you say, which may result in increased arrow velocity, if the energy stored by the increased power stroke more than offsets the energy stored by the slightly higher poundage with the higher brace height.
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Good topic...
One more thing to think about a shorter brace height has the exact same effect as a harder side plate, leather vs Velcro. When changing the side plate on the shelf from Velcro to leather it will move your arrow to the left (righthand). The brace height has the same effect as how much the bow is center cut only on a smaller scale. Everyone agrees that you can build the side plate out to shoot a lesser spined arrow, right.
The bottom line is if your arrows are spined correctly, the difference in brace height is minimal but it is a difference.
Sorry if I sound opinionated on this matter, what can I say, I'm very passionate about tuning. :)
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SELFBOW19953 -- I think that the "why" does matter, at least so me. I don't want to just randomly increase or decrease my brace height and hope that I stumble upon the right string length for my setup. If my arrow is slightly stiff, I'd like to know if I'm better off increasing or decreasing my brace height. Plus, I just find the mechanics and physics of this hobby fascinating.
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NothingHappenedToday-
Thanks for a great thread, sometimes the simplicity of traditional archery is not that simple. A few years ago I saw a similar thread on another site and it was pretty much divided down the middle on opinions. Through my trials and errors have to stand firm on my beliefs.
Go out and play with your set-up and see what works best for you. After you do, please report back on your individual findings. From looking at your avatar it looks like you have great form and should be able to come to your own conclusion.
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If you actually spend time testing it, you'd know the answer :) Think of brace height as preload on your limbs, the higher the brace, the more preload on the limbs transmitted to the arrow. The lower the brace the less preload you have.
You shorten the power stroke when increasing brace height, and lengthen it with a low brace height. Think of it as horsepower, the more stress you put in the limbs, the more initial power you have, but because the string is now shorter, you have taken away some of the limbs travel at the end of the stroke.
Lower brace heights are faster because the entire power stroke is longer. Higher brace heights are slower because the string is shorter.
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I adjust my brace for quieter and the beat feel. Maybe the editor got the phrase wrong in the book. It does happen
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Lets not forget the change of arrow angle when changing brace height. Lowering brace in effect moves arrow further from center shot at window(points further left for RH shooter) so it shoots stiffer. Raising brace moves arrow closer to center shot at sight window(points more towards target), shoots weaker. Also agree raising brace increases poundage and makes arrow shoot weaker, at least for me. Clear as mud now. :biglaugh:
Either way the effect is very small and may help with extra fine tuning, like trimming or moving out a string silencer makes arrow shoot weaker, etc.
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I copied this passage from Easton's Tuning Manual:
"For recurve bows, another way of altering arrow spine is with the brace height. By increasing or decreasing the distance from the bowstring to the pivot point of the grip, the dynamic spine of the arrow can be made slightly weaker or stiffer. Increasing brace height will make the arrow shoot weaker, and decreasing brace height will make the arrow shoot stiffer."
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So Mr. Ferguson's book and Easton's manual contradict one another? Hmmmm.
I will set the bow up and stay within the bowyers recommended brace heights for max efficiency. Prefer to tune arrow and centershot for tune on a non ILf bow.
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Caughtandhobble is correct. It's not about the poundage or the power stroke. It's about the angle of the arrow to the riser. The closer the nock gets to the riser the more acute the angle to the left (for a right handed shooter).
Therefor, increasing the brace height makes an arrow act weaker...a lower angle when the arrow leaves the string.
Try it for yourself. Opinion doesn't have anything to do with it. Byron is wrong.
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Its the angle. Somewhere on this website there is a good picture describing brace height and the arrow angle as it leaves the bow. I will try and find it. This is more dramatic on bows not cut close to center.
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I know what works for me. When I started trad. over 25yr ago I was told if your arrows are shooting straight but are going to the left some you raise your BH up until your arrows start to come back to center. This is for a right hand shooter.
This has worked for me ever since.
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Maybe both are correct? So, since changing brace height changes the angle of the arrow on a non-centershot bow, then there's no angle to change on a centershot bow. Therefore, INCREASING brace height on a centershot bow will stiffen the arrow (shorten powerstroke/transfer less energy to the arrow), but will weaken the arrow on a shy-of-center bow (change angle of arrow more towards center).
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I think somewhere this got off track, you want your bow to shoot at its best for you, sure you need a good starting point,most of the spine charts are a good place to start, the bowyers suggested brace height should be followed, then find an appropriate arrow using the spine chart,then you should find the (sweet spot) on your bow, different arrows have different sweet spots they all have one,this could take some time and experimenting with brace height but should not be much, in the end you find what works best for you,nothing is a given. To say one way works best for all is misleading, the bow will tell you what it wants. Different bow designs, three fingers under,split finger,draw length, rest and plate material, and type of string all play a part. Generally speaking match the arrow to the bow set up and not the bow to the arrow, and kiss, arrows are cheaper than bows.
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I'm with Mark here totally on this issue.
I wouldn't recommend changing the brace height on your bow to tune arrows at all....
Yes it can effect the arrow spine a little bit, and on bows with the shelf cut "Before center" or even cut "To-center" changing brace will have more effect on point of impact windage.....
But it also has an effect on the bows efficiency, how quiet it is, and the amount of vibration.
Every bow has an optimum brace height where the string is at it's peak tension level. That's where you want it to stay. Its always best to tune your arrows to your bow after finding the sweet spot in the brace.
Changing strike plate material density, and thickness is another way to fine tune an arrow to the bow.....If that doesn't work you need to consider different spine arrows...... My .02 cents worth...
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Let's say you're out roving on a warm day with your bow with a relatively new Dacron string. As the day wears on, the string stretches and the brace height lowers. What is the effect on your arrow flight?
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Would have the effect of weakening the dynamic arrow spine little, but probably not enough to notice in how the arrow flies. As I pointed out in my initial post, small changes in brace height that some folks use to tune are really small. They yield very small results. Some folks say they can detect these results. Most can't, IMO.
Really not something to get one's undies in a bundle about. I tend to do what Kirkill does, i.e. manipulate brace height to find the sweet spot and do any additional tuning with point weight, arrow length and side plate thickness. Of course, the sweet spot itself is also influenced by arrow length, weight and weight distribution, amount of centershot, etc.
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I'm not too precise. I check my brace height with my palm and outstretched thumb. :)
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My own findings show an increase in bh weakens arrow spine, and decrease stiffens spine.
Best thing to do is test it for yourself...drop your bh to the lowest recommended and shoot a group. then crank it up to the highest recommended bh and shoot a group. What are Your results?
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Originally posted by Smallwood:
My own findings show an increase in bh weakens arrow spine, and decrease stiffens spine.
Best thing to do is test it for yourself...drop your bh to the lowest recommended and shoot a group. then crank it up to the highest recommended bh and shoot a group. What are Your results?
Exactly. :thumbsup: ... How hard is that to do? And while you are slowly changing your brace height, pay attention to how the bow feels in your hand after you drop the string...and when it becomes the most quiet....You'll find it's both at the same brace height and that IS the sweet spot. It will also give you the best performance at that brace...
Then ya leave the dad burn thing alone, and tune your dad burn arrows, or adjust your strike a bit...
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With all due respect to Byron, raising the brace height will weaken dynamic spine and vice versa. This question probably wins the award across archery forums as most debated topic...and the responses are always about 50/50, lol! Which tells you something else...if our form was perfect enough, we wouldn't have to ask and could all agree. The rest are just guessing, lol. Not a criticism, I certainly had to research it. Somewhere there's a PhD dissertation on it. Turns out the logical power stroke argument loses. If I remember correctly, it's the fact that a low brace height keeps the nock on the string slightly longer affecting paradox and biasing the path of arrow travel back to the left (RH shooter). Don't blame me, I didn't dream it up...but I did stay at a Holiday Inn Express last night. The downside, if you were counting on a few twists (untwists) to solve all your tuning woes...probably not going to happen! Most can recognize crappy arrow flight and it's a bigger problem than BH adjustment.
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Interesting and entertaining thread, at once. many good theories and perspectives.
I used to go with Byron's idea; more recently my experience has been different. Not saying right or wrong here; but as is so often the case: whatever works for you and your set up.
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Byron's theory works on my PL, I am not surprised that I'm not more surprised.
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Ken Beck says in his tuning video that in his experience and against what logic says…increase the brace height for an arrow that is too stiff for a Widow. Decrease for a an arrow that is too weak.
… unless I'm remembering that wrong. Anyone recall seeing that video?
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One caveat, I don't recall whether the author was dealing with a recurve or a long bow. As I think we can all agree that the former are generally cut past center and the latter cut shy of or to, it may at least partially explain why "our mileages vary".
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Even with hill style bows, different things will get different things, depending on the bow. John Schulz suggested a very low brace and only 1/16" above 90 degrees for the nocking point for his reflexes glass backed bows. You may find that will not be right for a Hill Archery bow. For a mild R/D bow like a Robertson, you may find something different as well. In another video about tuning, Byron suggests going with setting the brace towards the high end of the brace suggested tolerance for getting the most forgiveness in a hunting bow. John Schulz also stated that running a higher brace height with his bow could sacrifice a fair amount of cast. I find that with a bow that is more whip ended than average that I get a loss in cast. With other bows, I cannot tell that it makes all that much difference from going from the middle of the span to the lower end. As far as what spine arrows work out of a Hill style bow, I find that there is more of a difference when a bow is shot with dynamic form versus dead form as long as the brace heights and the nocking point positions are within suggested tolerances.
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"dynamic form versus dead form"
Are you referring to using a solid anchor vs a floating anchor? or snap shooting vs holding at anchor? I'm just curious Paven... never heard that terminology before.
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I have noticed some of the guys that I shoot with will plant their thumb knuckle behind their jaw bone and lock their bow shoulder against their head. When they release their fingers come forward infant of their anchor, then after the arrow is long gone they have an artificial after the fact follow through. That is dead form. What I call dynamic is when the release at the very least, maintains the draw length, or even better springs back a bit, with the bow arm having a sprung resistance against the bow keeping the bow shoulder off the side of the head. When I shoot a Hill style bow, the bow hand jumps a little bit forward and the release hand jumps a little bit back. At least, that is what I try to do.
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I think it's a typo, because I know he knows better.
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These are the differences between a dynamic release and a dead release:
A dynamic release is a "pull through" release, meaning that movement, however slight, never completely stops. There is never an actual "hold" where the arrow stops moving during the draw. As a result of this increasing tension during the draw, the drawing hand typically ends up behind the neck or on the shoulder after release.
A dead release is a release where the back muscles are locked off at full draw, similar to the way someone doing a pull-up may lock off at the top of the pull-up, before starting the next pull-up. There is an actual hold in a dead release, where all movement stops, and aiming takes place. There is no increase in tension through release; the arrow is simply let go. Since there is a balanced pulling during the hold, where the force of the archer pulling back is equal to the force of the bow pulling forward, there should be some slight movement of the string hand back on release, although not as vigorous as in a dynamic release.
Alignment and posture in a dynamic release and a dead release should be exactly the same.
I have studied under Rod Jenkins, who teaches the dynamic release, and Rick Welch, who teaches the dead release. My impression is that the dynamic release works best for most people. Being contrary, the dead release works best for me.
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You can have a dynamic release and still have a hold, one just has to resume pulling and expanding during the release.
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I think one of the wonderful things about traditional archery is that, though you try to define things, no two people actually shoot the bow the same way.
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One of the best longbow shots that I have ever seen on still targets, besides my son, would draw and slow to a near dead stop at anchor and then do a slow spread for about a second and a half. My son picked up that, I would have needed my Hoyt target bow to beat either one of them. I could out shoot either one on fast shots and moving targets, but that slow drag was impressive when they had an idea how far the shot was. I have never seen two Hill shooters do things the exact same way, everyone has their own little quirks that make things work.
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Both types of dynamic releases described by McDave and Paven would be considered dynamic.Its all about the string hand moving back naturally.Expand and pull through with the back muscles.
The other release can be called a dead release or static release.
You will see good shots with either style.Most Olympic shooters will have a dynamic release.
The bow seems to behave very well with a dynamic release and I think it may increase arrow speed a tad and it seems to promote a quieter shooting bow in my experience.
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Sometimes I'm amazed that after all this time spent with these incredibly simple weapons we make and use every day, that we can't come to a proper comprehensive understanding on such things.
My experience is that lowering the brace height makes an arrow act stiffer. And I always thought those effects were due to the angle, AND that the lower brace height kept the arrow on the string longer, which meant the arrow's tail end wasn't released by the string until 'later' and allowed to begin trying to clear the bow until it was closer to the bow... so, with a lower brace, the arrow has to be weaker in order to clear the bow.
Conversely, if an arrow is acting too stiff and isn't flexing around the bow, rather is smacking it, kicking off of it, raising the brace height will give it more room and time to get around the bow... i.e. 'act weaker'.