Author Topic: The finer points of tillering  (Read 12475 times)

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Offline markinengland

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Re: The finer points of tillering
« Reply #15 on: October 25, 2009, 01:37:14 pm »
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.

Rod

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Re: The finer points of tillering
« Reply #16 on: November 05, 2009, 11:42:28 am »
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.
« Last Edit: November 05, 2009, 11:58:42 am by Rod »

Offline bow-toxo

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Re: The finer points of tillering
« Reply #17 on: November 08, 2009, 06:33:06 pm »
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

Offline Davepim

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Re: The finer points of tillering
« Reply #18 on: November 09, 2009, 04:39:08 am »
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

Rod

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Re: The finer points of tillering
« Reply #19 on: November 11, 2009, 08:11:05 am »
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.

Offline bow-toxo

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Re: The finer points of tillering
« Reply #20 on: November 11, 2009, 05:19:25 pm »
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.

Rod

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Re: The finer points of tillering
« Reply #21 on: November 14, 2009, 10:42:30 am »
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.

Offline bow-toxo

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Re: The finer points of tillering
« Reply #22 on: November 14, 2009, 07:14:25 pm »
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.


Rod

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Re: The finer points of tillering
« Reply #23 on: November 20, 2009, 12:45:30 pm »
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.

Offline bow-toxo

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Re: The finer points of tillering
« Reply #24 on: November 20, 2009, 01:23:01 pm »
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.

Rod

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Re: The finer points of tillering
« Reply #25 on: November 25, 2009, 04:57:38 am »
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.

Yewboy

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Re: The finer points of tillering
« Reply #26 on: November 25, 2009, 05:19:12 am »
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