V定規や角定規、定規を使って
十等分の組合せの地割り方

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        As Temarikai has grown, the amount of information about Japanese V-Rulers or Angle Rules has also evolved. While our current information is now more clear, the collected information from the early years remains below. Here is a fresh start though, which should make things a little more understandable.

        While Japanese books do indeed show the paper-tape method of working a C10 divide, by far the most common method shown is one using a dedicated measuring device for the C10, known as a V-Ruler. It is a flexible plastic device shaped like a V, with the inside of the V cut to the required angle of 72 degrees. Each leg has a metric "measuring tape" printed on it, hashed in MM and CM with an arrow on the 5cm (50mm) mark. Unfortunately this little gadget is produced and sold only through the Japan Temari Association in Tokyo, so obtaining them elsewhere is not possible. Some temari makers are fortunate enoug to have the real thing, thanks to folks that have been to the JTA and brought some home to share. Many other crafters make their own (see info below) which is indeed possible with some cautions: be sure to use heavy enough card stock, or lamination afterward to insure that the angle of the V is solid and does not wobble (it should not pull apart or collapse in use). Using heat lamination rather than self-adhesive lamination will provide a very similar "heft" to the original pieces from Japan and give better results.

       Using a V-ruler eliminates the need for any other supplies other than a tape measure and is indeed a quick, direct way to divide a mari to a C10. You need only know the circumference (distance around the outside of the ball at the largest point - the obi/equator) in cm. For those not comfortable with using metric units - trust us, you will want to for this and it is simple - you only need to use the reverse side of a standard measuring tape. Once the circumference in CM is known, you then determine the V-Ruler value for that measurement. It is an easy calculation but, a simple reference chart eliminates the need to calculate values for most standard mari sizes. For reference, the formula is an easy three-step. For the non-math folks: divide the circumference (that you measured in cm) by 6, and remember that result (call it Result A). Divide the circumference by 100 and remember that result (call it Result B).  Add Result A and Result B together, and you have the V-Ruler value you need for your mari. For the math folks, it's written as (circum/6)+(circum/100)=V-ruler value. 






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Several references have been made in on this site and it is something that you will see in most Japanese Temari books - about a device used in Japan to divide wrapped balls into the complex 10/pentagon division. It is commonly called a V-ruler. While not available outside of Japan, an image is provided here along with instructions. In reality the gadget is made of thin, flexible plastic. The inner angle is the standard 72 degrees, that of the pentagon angle. Each arm from the center back center measures about 9.5 cm long and 1 cm wide. The markings are in millimeter increments beginning at the apex of the angle on the interior. In reality it would not be difficult to create one yourself, out of light weight cardboard or paper that is then heat laminated. Should it become worn you can always make another.

        These instructions are from Sarah R -    
     To use to mark a complex 10/pentagon ball: measure the circumference of the ball in centimeters. Place the north pole pin anywhere on the ball. Position the measure on the ball with the north pole pin (pin A) inside the "V" of the measure. Using the table below, determne how many units (mm) from pin A to place pins B and C. Then swivel the measure so that pin A is till inside the V and pin C is stil against the measure as the second reference point. Place pin D at the same distance from pin A. All of these pins are equidistant from each other. Continue in this manner to place the pins around the ball and then use the standard methods of wrapping the marking threads.
     In reality most balls are not perfectly round. If you are having difficulty having the pins come out equally spaced from each other, start over by placing pin A in a different place on the ball. This often works (even if you have to make several attempts). It is important to note that it's almost impossible to get this divison totally accurate even when using this method and millimeters.... most of the time the closest you can get it will work.

Table of ball circumference and pin distances:

Circum (cm) Pin Distance Circum (cm) Pin Distance Circum (cm) Pin Distance Circum (cm) Pin Distance
25 4.4 28.5 5.04 31.5 5.56 34.5 6.09
25.5 4.5 29 5.12 32 5.65 35 6.18
26 4.55 29.5 5.20 32.5 5.74 36 6.36
27 4.67 30 5.3 33 5.83 37 6.53
27.5 4.85 30.5 5.47 33.5 5.92 38 6.71
28 4.94 31 5.47 34 6.00

(With much thanks to Sarah Robinson)
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Hints from Martine:
I have tried all methods and stick to the V ruler. To me it is the fastest especially if you use an already calculated division table. If you don’t have the table (I got mine at a temari gathering) measure the circumference, divide by 6 and make a note of that number. Next divide the same circumference measurement by 100. Add this answer to the first answer. This is the number (length of pentagon side) that you will use to place your marker pins.

As for the actual pin placement-the directions should be on the site somewhere. The trick with the V ruler is how you smooth the leg down –don’t touch the point of the ruler behind the pin-make sure it is not lying flat on the ball-then proceed to smooth the leg down and place pin at appropriate number. This is SO fast as it does not require dividing ball into tens, moving pins etc……..  Martine in Alabam
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Sue Hayashi also offers her thoughts on using the V-ruler and it might be a little more clear this way:

Download PDF file with accurate angle ruler image - be sure to print at 100 percent image size - do not use the fit to page option.

To use the V tool: Start by finding your N & S poles. Divide your ball into 10 divisions.  You can either mark them outright, or just leave the pins at the equator distance from each other. When you allow the inner angle of the V ruler to straddle one of the pole pins, you will find that the legs of the ruler line up with two of the 10-divide lines.  (note these lines are not adjacent they will have one line in-between). Hold down the tips of the legs (near the equator).  Allow the outer edge of the Angle part to ride up the pole pin, but not the inner angle. Use your "magic" number (Circumference divided by 6 plus 1/100) in millimeters... count that number from the pole down each of the legs, and move every other pin accordingly. Once all your pins are moved to their proper positions from their respective poles, it becomes very easy with the V ruler to check that each pin is the same "magic number" distance from any other pin by allowing the ruler to straddle a pin, and gently holding down the legs toward two other pins.

    I hope all of the above makes sense.  Please do not hesitate to ask further questions if you are having difficulty using the Angle tool.  I will be the first to admit that it is not necessarily the first thing I grab for when making a C-10, but it is definitely handy when one is trying to make sure all the pins are the same distance.
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Hint from Jan -
Sue H. was kind enough to send me a copy of her scanned V-ruler.  After some tweaking, I was finally able to maintain the 72 degree angle and an equal length in the legs of both sides.  The measurements gradually increase to a total of one additional mm in length, than what their true measurement should be.  As I played with the printer on this and re-measured the markings on each, it occurred to me that a plastic coated tape measure with metric markings could be cut into two 9.5 cm lengths.  These lengths could then be joined (stitched through their overlap at the top or glued onto a piece of cardboard or a piece of plastic, say from the clear report covers available at office supply stores) at a 72 degree angle.  This way, the mm markings will be quite accurate and possibly an inexpensive alternative to the Japanese V-rulers.
Jan

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Last updated 9/04 © From 1998 inclusive G.Thompson, Sarah Robinson and Sue Hayashi