The finer points of tillering

[longbowman]

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

[Et_tu_brute]

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.

[longbowman]

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?

[Et_tu_brute]

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.

[alanesq]

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)

[Ian.]

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.

[alanesq]

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?

[Davepim]

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

[alanesq]

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

[Purbeck]

[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

[Davepim]

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!

[bobnewboy]

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. 

[Del the cat]

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

[Ian.]

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.

[Tom Leemans]

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.