Checking The Tiller

How to make a Bow, a String or a Set of Arrows. Making equipment & tools for use in Traditional Archery and Bowhunting.

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greybeard
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Checking The Tiller

#1 Post by greybeard » Sun Feb 23, 2014 12:52 pm

Until this morning I had not seen this method for checking the tiller on a wooden American flat bow.

The bow is 68” n to n. The diagram for checking the tiller is interesting.
Testing The Curve Of A Bow.JPG
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The following is the introduction to the article published in Outdoor Sports. I believe that it would be a fair assumption that this is an American publication.

There is no date on the publication but the price of a lemonwood stave and the archers garb may suggest mid to late 1940s.


"Now you can shoot
THE NEW American FLAT BOW
When the white man provided the American Indian with a cheap trade musket in place of his native bow and arrow, he saved himself a good deal of grief, for had the red man developed his weapon along a logical path he might have arrived at an approximation of the bow we now know as the "semi-Indian," "flat," or "American" bow. With such a bow he could have shot with accuracy at a hundred yards (about the extreme accurate range of the long rifle), and could have delivered arrows faster than any frontier scout could load his rifle.
Any home workman, equipped with ordinary tools, can readily build the most modern and most efficient bow yet designed. The best material for the amateur is the imported wood known as "lemonwood." It can be worked almost entirely by measurement, without much regard to the grain. California yew and Osage orange probably make a better bow, but not for the inexperienced builder.

Lemonwood can be had from most dealers in archery supplies, either in the rough stave or cut to approximate outline. The price ranges from about $1.75 to $3. In ordering you should be careful to say you need a wide stave for a flat bow."

Lemonwood Bow.jpg
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Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

Dennis La Varenne
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Location: Tocumwal, NSW. Australia

Re: Checking The Tiller

#2 Post by Dennis La Varenne » Sun Feb 23, 2014 4:15 pm

Daryl,

I have just recently read this very article in one of my older archery books and I am trying to find it again. I will post the reference up as soon as I have located it again. I think it may have been in one of Larry Whiffen's books.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

KellyG
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Location: Riley, Kansas, USA

Re: Checking The Tiller

#3 Post by KellyG » Tue Mar 04, 2014 12:06 pm

Man the picture makes it look so hard. I just like scraping limbs until they bend and fling and arrow. :lol:

Dennis La Varenne
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Joined: Sun Sep 07, 2003 10:56 pm
Location: Tocumwal, NSW. Australia

Re: Checking The Tiller

#4 Post by Dennis La Varenne » Tue Mar 04, 2014 1:59 pm

Kelly, it is not really as difficult as it seems, but I have seen simpler versions of it. This schematic is for a straight ended bow with a 28 inch draw, but it could be modified for a shorter draw by drawing those arcs at 26 inches or whatever required. To draw the arcs, all you need is a pencil tied to a piece of string with a nail at the other end so you use it the same way as a school compass to draw circles.

Firstly, you draw the 36 inch baseline on a surface (full size) and then you draw the 39 inch line at right angles to it.
Step 1.jpg
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Secondly, draw straight lines from the top of the 39 inch vertical line to connect with the baseline at each end forming a triangle.
Step 2.jpg
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Thirdly, draw your arc (representing your draw length) to cross the 39 inch vertical line with the focus of the arc in the middle of the baseline.
Step 3.jpg
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Fourthly, where the arc crossing the vertical line crosses the lines which are the sides of the triangle, use that point as the focus of the arc which forms the belly of the bow at intended draw length. Draw the arc on one side then the other at that same spot.
Step 4.jpg
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Those two arcs represent the curvature of your limbs at a full draw of 28 inches. At full draw as the diagramme says, your limbs should ideally fit the shape of these arcs. Being circular, they will be close to ideal in terms of bending load distribution over the length of your limb.
Step 5.jpg
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Importantly, this diagramme is for a bow with zero tiller and equal length limbs.

It is also worth noting that this schematic can be adapted for bows of shorter or longer draw length.

For instance, if the shooter wants a bow drawing 26 inches, you just shorten your string and pencil compass by 2 inches and draw the green arc, then from where the blue triangle lines intersect the green arc, you can then use your 26 inch string and pencil compass to draw the orange curves representing the desired shape of limbs at the shorter draw; and, vice versa of course for longer drawlengths.

My presumption here is that the length of the base line at 36 inches wide and 39 inches for the height line is set for all straight limbed bows.

If you wish to induce a particular tiller in your bow after it fits this particular curve, you can take about one inch off the bottom limb to induce a ⅛ inch positive tiller in the upper limb. Alternatively, if the bow is made from wood, just leave it alone and shoot it and it will take on its own 'customised' tiller depending upon how you hold and shoot it - with one exception - so long as you do not 'heel' your bow. Heavy heelers tend to induce a bad negative tiller in bows and put the limbs badly out of time with each other with the bottom limb taking a significant set compared to the upper imb.

If you don't heel your bow, a zero tillered bow will adapt itself to your shooting style.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

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