Tim's Oak bow/ todays gathering

badger5149
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November 14th, 2005, 8:16 am #1

Some of our Paleo group got together again today for an impromptu gathering, seems they just happen allmost every weekend now. Tim had built one of his 1 hour special oak board bows and I asked him if we could break it in over the chrono instead of the traditional method of getting it to full draw, The logic behind this was that we wanted to find out the optimal weight and draw for this particular bow, in other words, let the bow tell us instead of us tell the bow for a change. The results were very impressive for a 67" long 45# red oak board bow. And good news for the short draw guys like myself, we dont have to give up perfrmance because of shorter draws, I will post the test results below

The bow:
Red oak board, fairly dense, about 11%mc.
67 1/2" long, the center 18" exactly 1" wide.
Weights exactly 16 oz.
135-grain string, 3-grains per pound exactly.
Strong elliptical tiller.

23-1/3" 42.5lbs 154fps 490-grains
24.5" 45lb 156fps 490-grains
25.5 45lbs 163fps 472-grains


Corrected for arrow weight, at 25 1/2" and 45lbs it shoots ten-grains 165fps, exactly plus-20. Not snap shot, but a normal hunting draw. At the same draw length you could likely get five more fps out of it. I'm guessing it had been pulled to almost full draw, measuring and shooting, about 15 times, to full draw maybe 5 times?

1 1/4" just unbraced set. 7/16" hours later set

Commentes:
The outer limbs could have been narrower, for another couple of fps.

Just looking at the raw stats doesnt say much but is worthy of some discussion by newbees and old timers alike,

makes me wonder how many good bows we never knew we had because of preconceived notions of draw length and draw weight that were not optimal for the piece of wood we were holding in our hands at the moment.

The bow above is probably within 95% of its best ability. I think the lesson lies in learning how to recognise the signs of a bow comming to its peak. Steve
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Rod
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November 14th, 2005, 8:57 am #2

How do you know that is optimal performance without carrying on until it shoots slower?
Rod.
It's meant to be simple, not easy.
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Tim Baker
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November 14th, 2005, 10:16 am #3

Rod: I don't think Steve meant the bow would begin to shoot slower with increased draw, just that it would begin to shoot slower per pound of drawweight, that it's true efficiency would drop, As draw length increased from 20" to 24.5" drawweight rose also. But at about 25" drawweight increase began to level off, due to belly wood surrender, the bow going from essentially no set at 20" to 1 1/4" at 25.5. If drawn farther set would increase dramatically, lowering early drawweight/energy storage. and speed per pound.

We were loosing our chronographing light or we'd have continued on, sacrificing the bow to science [instead of a bog]. Next Sunday we'll continue the test, drawing it half-inches farther, noting weight, length and speed, till reaching 28" or until it breaks. The bow is only one-inch wide, so we'll keep the weight at 45lb as draw increases. This means we'll likely have to thin the bow a touch to avoid excessive drawweight/strain.

But there is a danger here too: If thinned for a longer draw we'd be asking less wood to store more energy, so the remaining wood will be under even more strain, taking even more set, or breaking. My guess is that Steve's appraisal is about right: that the bow has peaked as far as speed per pound is concerned. But we'll see.

Tim
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Rod
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November 14th, 2005, 10:43 am #4

I agree, but in terms of proving the test it is necessary to go past the peak so as to postively identify it.
Rod.
It's meant to be simple, not easy.
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Fundin
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November 14th, 2005, 12:25 pm #5

Just a thaught that seems a little obvious.

1 Longer draw lengths store more energy.

2 Steve and Tim has recently made bows peaking at 22 and 24" of draw length....

Well, same design, but peaking at 28" How fast would that be?

I would love to see some pictures of theese high performance short draw bows, as I myself shoot best with a 25,5-26" draw.
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badger5149
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November 14th, 2005, 6:45 pm #6

The thing I am finding interesting about this whole thing is that at this point I am at right now, I havent been able to get the "peak" any different for longer draws than at the shorter draw lengths, I am fairly certain there is a simple puzzle involved with mass, demensions, draw weight and draw length that relates to scale. If I am right this would mean I would have to lean toward lighter woods as with Tims oak bow yesterday at 1" wide any narrower it would start to twist, We are not talking super fast performance bows here but just sound principles for building a good bow. Another observation I have made ( not fact) as I may be observing wrong but it is starting to appear to me that the 5/8 rule as used in english lonbows just may be a superior design if the proper length, width, and draw length were selected, building a bow as above and having no hard fast predetermined goals as the where it would end up outside of at its peak may lead us into better dememsional efficiency. Most all of my longbows, with a few exceptions have been mediocre performers, some of my better performing longbows have been made with woods such as western cedar, doug fir, poplar, soft maple etc, all light woods that are not truly suitable for bow work but because of their low mass lend themselves to light draw weight bows with the proper demensions. Some of my best performing heavy dense wood bows were also built to 5/8 rule scales but much too short to be considered longbows. I really suspect if a few guys went out and built bows of say 4 woods with different masses, say poplar, maple, osage, ipe. and played around till they found optimum demensions with length, width and draw to the point where they all had about equal performance a pattern would emerge that could be converted to a simple formula for predetermining better demensions than we use today. Throw away the thought of performance goals and think more in terms of optimization. I think once we do this good performance will simply be a bi-product. Kind of a brainstorming workshop with a few dedicated guys, some power tools to speed the process up a bit and a pile of lumber would all that would be needed and possibly a guy like woodbear hanging there to do models for us and help direct the line of thought. I really like the idea of building bows that are full tillered, straight, and symetrical, especialy if they can be made to work well. I have always operated under the assumption that there was a direct relationship between thickness and length and figure the width would only determine the final draw weight, Starting to think now that a relationship that may be more subtle but still meaningful exist between width and thickness as well. Just as the english longbows suggest. This would mean the length of the bow would be the one getting adjusted for optimizing rather than the width or the thickness. No sure how the properties of the wood would play into this, some being inherrently more eficcient due to a natural better matching of tension and compression woods. Just thinking out loud here.
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Tim Baker
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November 14th, 2005, 9:10 pm #7

As per usual Steve and I disagree on many points here:

The 5/8 limb section is a guaranteed route to poor performance unless using wood with a high elastic limit like yew, and even here a wider, thinner limb is best, as long as the outer limb is narrow.

Lighter wood offers no advantage if the bow is designed correctly for the heavier wood: As with all designs, keep the wider portions restricted to the slow-moving inner limb, the outer portions narrow. In the case of heavier woods the outer limb must be, and can be, even narrower, to yield the same mass as wider lighter wood.

"Most all of my longbows, with a few exceptions have been mediocre performers"

Possibly the fastest straight-stave bow in the known universe is 80" long. Longer bows have an inherent speed advantage if designed appropriately: the mantra: wide enough or long enough inner limbs to barely bend, but not enough to take ANY set. midlimbs just wide enough to take little set, outer limbs narrow for low mass.

If the 1" bow in question here had been 2" wide it would be 90lb at 25.5" or if thinned a bit it would be some lower weight at 28", at which it would shoot somewhat faster per pound than the present version. If a few incher longer, with increased elliptical tiller, it would shoot a bit faster still.

Steve;s Idea of tillering a bow to it's peak is valuable for two purposes: getting the greatest speed with safety for a given stave, if you don't care what drawlengt or weight emerges. And learning the nature of a particular wood, that info to be applied when designing a bow to a desired weight and drawlength. Alone, it's not a practacle way for the typical archer to make a bow becasue it yields a draw lenght and weight of some random figure.

Once you know the general nature of a particular wood you can dial in near exact length/width for your desired draw lenght and weight. If designed as above it will shoot at world-class speed yet with high durability.

Ball's in your court, Steve.

PS: Yes, it's not all that important if a bow shoots a few fps faster or slower. That's not the reason archery is so rewarding, and a genera and eternal search for more speed, is a guarantee to diminished contentment. But. If the search itself is seen as a hunt, a seperat activity, where once having left the 'lab' you can pick up a quite ordinary bow and be happy, then it's a proper course, one result being that your ordinary bow will be a faster, safer shooter. Tim
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danceswithtrout
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November 15th, 2005, 12:02 am #8

So , I;m not sure I follow this line of thought correctly. Steve, are you suggesting that perhaps if we played your new idea out a little further theat eventually we could get to some point where we could look at a wood species we wanted to build with. Then have an optimal x/y (5/8 rule) for eacjh species of wood and we would then adjust the lenght to arrive at the desired sraw weight? Is this thinking ending up on the same route as you introduced in the above? I'm kinda slow sometimes trying to keep up with you guys since I hav eonly been bending/breakin bows for about 8 months. I just love to hear you guys thinking out loud.
Keep it up and thanks!

Ryan
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Rod
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November 15th, 2005, 12:05 am #9

In my experience the component in the equation most often suffering from mediocre performance is commonly provided by the man shooting the bow. In this context, relatively minor variations in bow performance pale into insignificance.
Rod.

Be smart, build a better archer.
It's meant to be simple, not easy.
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DeLaChaumette
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November 15th, 2005, 12:24 am #10

I've noticed over the past couple of months my shooting has improved. My arrow grouping is closer and more consistant. It's not because I've made a better bow, I'm just spending more time shooting instead of building...
JOhnny
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danceswithtrout
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November 15th, 2005, 12:38 am #11

Dang
You would think I was a 7 year old as bad as my typing and spelling is in the above response. I know I can't spell , I allways thought it was wierd to to see (skndf9876254) sp? Anyway on to my point wich is somewhat related to the last one.
I realise deep/narrow designs -vs- flat/wide came about to best utilize a certain wood species in a way that would complement its natural makeup. It also seems that by combining different backing/core combos allow us some freedom from flat-vs-deep.
Heres what I mean. I might be wrong here cause I haven't built both of these bows yet but; If I made an ELB style bow following the 5/8 rule with Hickory backed Ipe , if it was optimally made it would performe to some figures that you would expect, and Steve would add to that that he believes it would have a total mass of a certain amout to fall into "optimal" performance. I think we all agree to this so far don't we?

Now, Take and make a Hickory backed Ipe flat bow, adjust the thickness of the backing strip to a more appropriate thickness so it doesn't overpower the Ipe and make this bow "optimally". It too would have some performance standards that you would weight it against to get it to function in the "optimal zone" and again it would also have a total mass weight of a certain amount of ounces.

Now , lastly lets marry these 2 designs together and have a "half bread" if you will only we leave the lenght undetermined and it falls where it may to arrive at the same draw weight/draw lenght as the above two bows.

Have we now done what you meant Steve by having many guys all building in the same experiment?

And , if so , what do we learn here that we didn't know/don't now before these three bows?

Assuming we can make these three and they all weigh the same in total mass, end up with the same draw weight at the same draw lenght, now whos to say wich is the better bow?

Is this not still personal preferance/speculation?

I guess what messes me up is when I read Tims stuff in the "bibles" and then read Dean Torges stuff in his books and then add to that the conversations I have enjoyed with Steve they all seem to make perfect sense.

Seems to me that even if we were to break the 200 barrier (wich I hope and do think someone will soon) that only says who's bow is the fastest and still doesn't answer the question of maximum performance per design/wood combo.
So what is (the) dipstick to measure maximum performance?


Lost in space

Ryan
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Rod
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November 15th, 2005, 1:03 am #12

It's not a dipstick, it's an arrow.
It's meant to be simple, not easy.
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danceswithtrout
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November 15th, 2005, 1:13 am #13

So Rod

Are you sayiong that the tell all about a bow designand/or a bowyers competence is determined by how accurate you can group your arrows?
I once had a dream to play golf as a profession and was a scratch player and had friends and aquatences that were much better than myself. I know this to be true both in golf and in fly fishing: a person with developed skills can take a k-mart special and make miracles with junk and you can put my golf equipment in other guys hands and they wouldn'y brake a hundred. Without a doubt the guy with more refinedskills can enjoy the better gear in a way the novice wouldn't even notice and still make majic with junk.

I don't think a good, or bad "group" of arrows says anything definitive
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Rod
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November 15th, 2005, 2:02 am #14

So what is a bow for other than to project the arrow?

"You can deceive yourself but you cannot deceive the arrow."
It's meant to be simple, not easy.
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PaleoAleo
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November 15th, 2005, 2:59 am #15

Can someone explain the 5/8th rule to me? I've been a bit confused about that since first hearing it. As a result, I'm having trouble following the full gist of the discussion(s).

Tom
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badger5149
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November 15th, 2005, 3:13 am #16

Tom the 5/8 rule dictates that at no place on the bow can the thickness be less that 5/8 of the width, for instance if the bow measures 1" at a certain point the thickness must be at least 5/8. Steve
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Rod
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November 15th, 2005, 3:18 am #17

The 5/8ths rule defines the least permissable depth of limb in the rules of the British Long-bow Society whose aim is to preserve the customary form and use of the long-bow, and specifically the sporting form typical of lawn archery of the 19th and early 20thC.
It is a rule particularly intended to prevent "improvement" of the traditional profile for competitive motives at a time when target archery was increasingly dominated by the flat limbed bow.
The rule states that at no point should the depth in cross section of the limb be less than 5/8ths of the width at that point.
Rod.
It's meant to be simple, not easy.
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badger5149
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November 15th, 2005, 3:21 am #18

Rod, what would be typical demensions( roughly) for a 160# longbow, mainly the length? And if there is a difference what would the typical length of a good shooting 100# bow be? Steve
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badger5149
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November 15th, 2005, 3:23 am #19

Also, approx what would be the typical draw length the big boys are pulling? Steve
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Rod
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November 15th, 2005, 3:42 am #20

Steve,
The 5/8ths rule need not necessarily be taken as a rigid prescription if shooting outside of the societies (BLBS/GNAS) where the rule is in force, though it IS a reasonable approximation in general terms.
There is a case to be made in certain circumstances for what one might call a "transitional" bow, either in the late neolithic/bronze age or in more recent times with the sporting bow.
As for bow lengths, where 72" is probably the median for a man's sporting bow, for a heavy war bow (150lb median weight), from 75" up to 80" or so (the Hathersage bow was about 79") is not unlikely, though the majority of artefacts are more towards the lower end in length.
I believe the Viking bows (Nydam/Vimose/Ballinderry/Heechterp) were perhaps a very little lower in weight and of a similar range in length with some shorter examples.
Rod.
It's meant to be simple, not easy.
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