wrote:
I'm making a wine rack:

http://www.uniqueprojects.com/projec...k/winerack.htm

and I was wondering how to lay out that sine curve on the piece of wood
to cut it. At first I thought of using a disk of some sort, but that
would yield a series of half-circles. If I can't finger this one out,
that's probably what I'll wind up doing, but I was wondering if y'all
had done something like this.

You've had all sorts of answers for how to do this with various computer
programs (or a pocket calculator), but here's another way that doesn't
involve anything but a compass, straightedge and protractor, and you can
lay it out directly on the board:

1.) Draw a horizontal line down the middle of where you want to put the
sine curve, with the ends aligned with where you want the ends of the
curve to go. Call this the "center line"

2.) Make marks (call them "section marks") to divide this line into
equally-spaced sections, one section for each up-and-down-and-back-up of
the sine curve that you want. Mark off divisions of each of the
sections into 16ths.

3.) Set the compass to draw circles with a diameter equal to the height
of the sine curve that you want to draw. Draw a half-circle centered at
each end of the center line, so it looks sort of like a C at the right
end and a reverse-C at the left end, and the center line goes from the
center of one half-circle to the center of the other.

4.) With the protractor, mark off angles on each half circle, at every
45-degree point, and every 22.5-degree point between these.

5.) Draw lines parallel to the center line by connecting the tops and
bottoms of the half-circles, and each corresponding pair of angle-marks.

6.) Go back to the marks you made in step 2. Starting at the left-hand
end of the center line, draw a line perpendicular to the center line
that goes all the way up to the top line. Put a dot where it crosses
the top line. (You don't actually need to draw the perpendicular line;
just draw the dot. But it's easier to explain if I say to draw the line.)

7.) Go to the right along the center line. For the next mark, draw
another perpendicular line and dot, but put the dot where it crosses the
second line from the top. For the next one, draw the dot on the third
line, then the fourth, and so on. When you get to the bottom, start
going back up. If you've counted right, you should get back to the top
line when you get to the first section-mark. Keep going until you get
to the other end.

8.) Connect the dots. If you're not good at sketching smooth lines, use
a french curve or something.

Obviously, the division into 16ths and the angles I picked are somewhat
arbitrary -- just so long as you divide the sections on the center-line
into twice as many divisions as you divide the half-circles into, it
will work out. If you're using drafting triangles instead of a
protractor, 12ths and marks at 30-degrees and 60-degrees will work well.
Or, if you're good at sketching with only a few dots (I'm not), just
make marks at 45 degrees and divide it into 8ths.

Is that clear enough, or should I do up some sketches and post them?

- Brooks


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