Primitive Archer
Main Discussion Area => English Warbow => Topic started by: longbowman on October 20, 2009, 03:18:31 pm
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I've just made my first bow and I'm really happy because if fires! However in reading numerous forums and articles etc I've come across talk about positive tillering, having the handle off centre thus making one limb shorter than the other. So what is a positive tiller and why have it? And also why make one limb shorter than the other? What effect does this have? Which limb should be the short one? If someone could elaborate on this issue that would be great. Thanks
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Longbows have the bottom limb as the shorter one. Basically when you are marking out the bow find the centre and put a mark on, then measure one inch above and 3" below the centre, this is your handle section, so you are shooting from 1" above the centre of the bow. Since the bottom limb is shorter it's under a bit more strain than the top limb, so some people use positive tiller to make the bottom limb a little stiffer than the top.
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Thanks for your reply. With a positive tiller is it the top limb that comes down 1/4" more than the bottom of vice versa? Why is the top limb longer than the bottom?
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To be honest I really don't know why the top limb is longer, sorry I can't be of more help. Yep with positive tiller the top limb bends a little more than the bottom, not necessarily 1/4", a bit more is fine.
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This is something I have been confused about?
Isn't the point of the marking 1" up and 3" down from the bows centre for a handle because when you hold the bow its not actually resting in the centre of your hand (its mostly held around the thumb joint area)
so actually the bow will be bending from its centre despite the fact the handle area is not at the centre of the bow ?
i.e. the handle is off centre to compensate for the part of your hand which supports the bow
- If the bow isn't supported at its centre then drawing the bow would tend to turn the bow in your hand as one tip has more leverage than the other (although this theory may not be true as Japanese bows are very off centre?)
BTW - This means that when tillering the bow should not be supported at the centre of where the handle is/will be - it should be around 1" down from the top of the handle (i.e. the centre of the bow)
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I think the 1" up idea is victorian, it would be good to know if the MR bows had the same layout.
I make all my bows bend in the centre, never had a problem if anything better in my opinion.
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I think the 1" up idea is victorian, it would be good to know if the MR bows had the same layout.
I make all my bows bend in the centre, never had a problem if anything better in my opinion.
It would be a more modern idea as longbows didn't have handles fitted until recently
It would be interesting to know how far from centre the bowyers marks are in the Mary Rose bows - have never managed to get an answer to this question?
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Mark Stretton recommended to me that the arrow pass should be about an inch above the centre of the bow, and I have followed his advice since then with no problems. However I also find that the centre of the bow bends in my hand anyway for a full-compass bow; it's not as if my hand impedes the bend in any way. In Hugh Soar's book, "Secrets of the English Warbow", there is reference to the stronger lower limb being require to generate a "lift" to the arrow upon release - don't know whether this is true or not. What is certain is that assymetry in the strength/length of the two limbs of a bow help to reduce the harmonics of vibration in the bow and thus reduce "kick". I should also say that the very first bow I ever made had the arrow pass at the exact centre of the bow and it seemed to shoot perfectly well. So I remain pretty much as confused as anyone else! ???
Cheers, Dave
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the important thing is where the centre of hard contact with your hand is in relation to the centre of the bow when you draw it
If the arrow pass is 1" above the bows centre then I think this will put this point at about the centre of the bow
the confusion seems to be that because the handle is not at the centre of the bow people think the limbs are different lengths
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[quote
It would be interesting to know how far from centre the bowyers marks are in the Mary Rose bows - have never managed to get an answer to this question?
I have read somewhere that many of the makers marks on the MR bows are way off centre and therefore do not mark the arrow pass!
Purbeck
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the important thing is where the centre of hard contact with your hand is in relation to the centre of the bow when you draw it
If the arrow pass is 1" above the bows centre then I think this will put this point at about the centre of the bow
the confusion seems to be that because the handle is not at the centre of the bow people think the limbs are different lengths
I think you've put your finger on it there Alan!
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The way I had it explained to me is that for most archers, the mediterranean loose or similar is used. Since this puts more fingers under the arrow than above, the fulcrum point formed by the string fingers pulling the string is below the arrow pass, and hence more effort is put into the lower limb. To alleviate this somewhat the arrow pass is moved up the bow by about the same width as two fingers pushed side by side on the string - approx 1".
In the end everyone making bows has their own way of marking and tillering which works for them. So long as the bow feels balanced at full draw, and shoots smoothly, the finest details are just personal quirks really, IMO. ;D
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There are no rules.
A bow is at first glance symetrical and you'd think both limbs the same length.
But just think about it...
If you mark the geometric centre of the bow and have the arrow there, then your hand will be below it, effectively shortening the lower limb. Factor in you have two fingers below the arrow and one above....more assymetry.
It's about compromise, and you can decide on your own... the arrow 1" above geometric centre is pretty sound.
The longer the bow, the less important it becomes (1" away from centre in a 72" bow is a smaller part than 1" in a 48" bow)
All of this is one reason why you should be carefull when tillering to support the bow where the hand pressure will be and draw the string back were the finger pressure will be. The assymetry also means if you have one limb stronger than the other then adjsuting the hand/arrow position or turning the bow up the other way may help cure the problem.
Your time is up...please insert another coin.
Del
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Remembering that archrs would mainly use 2 fingers to draw not 3, I dont think that a heavy bow will be that effected by having the arrow pass in the middle none of mine ever has been.
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The ol' debate or investigation of equal vs unequal length limbs has been going on forever. I think it has more to do with A: the dynamic fulcrum of the bow being in the web of your bow hand, as referred to above. Lends itself to balance properly in your hand; and B: Having the arrow pass nearer to the geometric center of the bow, lending to pointability. I guess this will be discussed as long as we continue to make bows.
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The japanese yumi bow has the handle way off centre and essentially unever tillering and the arrow significantly off 90 degrees to the string and this works very effectively.
If what breaks all the "rules" works well then maybe there are no real rules.
Some say that a bow with asymetrical tillering sits better in the hand on the shot but I can't say that I have ever been able to tell the difference.
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However you look at it you can't easily place everything in the middle.
At least not with a simple hand held bow.
Ishi's Yahi style comes close but that is a style that is mechanically weak outside of it's original context.
If you make a totally symmetrical bow, as soon as you pick it up, put an arrow on it and start to shoot it it becomes dynamically assymmetrical in the plane of pitch.
All we do is try to establish the most effective compromise in set up where the bow feels in balance and the spread of the group in elevation is minimised.
The classic solution is to have the hand pressure point on the centre of balance (dimensional centre of length) and the arrow resting as close above that point as is practicable.
The nocking point is conventionally slightly above this level so as to optimise clean arrow departure in the plane of pitch (eliminating porpoising so as to contribute to optimising the spread in elevation).
But the same principles can be applied to other variations in asymmetry to effect a workable result.
With a given style of bow, we quite often work within the appropriate tradition of the culture that historically used that bow.
Or not, as we choose. But I prefer the first course.
The yumi is no different except that the tiller is adapted to suit the degree of asymmetry in the bow.
Which side of the bow the arrow is placed is another topic and relates to cultural and functional factors, style dictated by holding shafts in the bow hand as it affects shaft loading, type of string hold dictating side pressures and the consequent effect on alignment of string rotation during the shot.
The "rules", such as they are, are properly functional and defined by how well the arrow goes where it has been aimed.
What else matters?
Rod.
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I think the 1" up idea is victorian, it would be good to know if the MR bows had the same layout.
I make all my bows bend in the centre, never had a problem if anything better in my opinion.
It would be a more modern idea as longbows didn't have handles fitted until recently
It would be interesting to know how far from centre the bowyers marks are in the Mary Rose bows - have never managed to get an answer to this question?
I wondered about that myself and checked it out at MR museum. Thery are about two inches above the handgrip, [ found as noted in Lartdarcherie by balancing the bow on the thumb, then closing the hand on the bow] on the bow hand side. The bowyers marks are surprisingly small, about 3/16". While there is no indication of wrapped handgrips, one of the bows shows a lighter section between handgrip and bowyers mark, I would suppose wrapped to avoid damage at the arrow pass.
Erik
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That's interesting. Maybe the bowyers mark was placed where it was to indicate the upper limit, below which the arrow should pass, and that as Bow-toxo suggested, sometimes it was wrapped.
Dave
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Perhaps it is not safe to make assumptions about the significance of the placement of bowyers marks without a study of the placement of such marks in relation to the centre of balance in the bow.
Rod.
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Perhaps it is not safe to make assumptions about the significance of the placement of bowyers marks without a study of the placement of such marks in relation to the centre of balance in the bow.
Rod.
I was pleasantly surprised to find tha the MR bowyers marks were in the same position as those I put on my own bows before I had any information other than that the MR bowyers marks existed. It seemed like a natural place to put them in relation to the handle/point of balance.
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Agreed, it is the assumption I might might make, but in a conversation with Chris Boyton some time ago he expressed the opinion that the marks were not always placed so precisely as to fully justify this assumption.
My ppoint is only that it would perhaps be of interest to see a systematic study of their placement relative to the centre of balance.
Rod.
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Agreed, it is the assumption I might might make, but in a conversation with Chris Boyton some time ago he expressed the opinion that the marks were not always placed so precisely as to fully justify this assumption.
My ppoint is only that it would perhaps be of interest to see a systematic study of their placement relative to the centre of balance.
Rod.
I only saw two or three and thought that was enough but would be happy to get additional information. Not all the bows had bowyers marks and I doubt that there is much more to it than individual preference. There seem lots of ways here to decide on handle/arrow pass position. I used to fret about it until finding the mrdiareval method in Lartdarcherie. Balance the bow on the thumb of the bow hand and close the hand. Problem solved. Also, you can't decide the bowyers mark position in relation to arrow pass until you have decided where the arrow pass position is.
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I can see that would work. My own preference would be to find the point of balance in the bow and place my point of contact there.
As far as bowyers marks are concerned, is it not just as likely that the mark just indicates the intended tiller by the bowyer marking what he considers to be the top limb?
Rod.
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I can see that would work. My own preference would be to find the point of balance in the bow and place my point of contact there.
As far as bowyers marks are concerned, is it not just as likely that the mark just indicates the intended tiller by the bowyer marking what he considers to be the top limb?
Rod.
I doubt it. Most MR bows had no such mark, and the marks were of various designs, I would think to identify the maker. Identifying marks were also used by other craftsmen for that purpose.
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I should perhaps have written the placement of the mark.
No matter, to rephrase the question, are all such marks in approximately similar positions relative to a centre of balance hand position?
Rod.
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I should perhaps have written the placement of the mark.
No matter, to rephrase the question, are all such marks in approximately similar positions relative to a centre of balance hand position?
Rod.
YES they are Rod