I cheated once. Took a coffee can lid and made a hole very near the outside
edge for a pencil.
Put a straight edge at the bottom where the sine wave was to go and rolled
the lid across the straight edge, marking the plywood.
The cutting and sanding were much, much more of a problem than the layout.
I gave up after a few attempts, because even the smallest error is
noticeable be everyone. Just a guess but the wine rack mentioned by OP
might hide small errors in the sine wave due to other objects which would
draw the eye.
When I need to make a curved cut in a piece of wood, I make a pattern
from 1/4" hardboard and pattern-route it. Hardboard is easy to cut and
sand smooth and if you make a mistake or cut a little too deep, you
can fill/repair it with a little 5 minute epoxy and file it smooth.
Once the pattern is perfect and smooth with the curve I want, I attach
it to the wood and route it. The end result is wonderful and perfect
the *first* time with very little sanding.
Plus, in some of my woodworking I often make many of the same items,
several at a time over a period of time. The pattern allows to me to
make perfect pieces time after time and very quickly.
On Sun, 19 Feb 2006 04:41:32 GMT, "Phil-in-MI" <NO Spam &
That's a cycloid, not a sine. Still far and away the easiest is to
use a graphing program like Graphmatica [download from
archives.math.utk.edu ...it's awesome and free.] Type in y=sin(x)
ENTER, and you then print from there or copy/paste into a word
processor. Less than a minute if you have both programs up and
It can be done by hand, it can be approximated by hand. ifthat's good
enough then that's the best way, but most people don't have a clue on
how to do that.
Now, let's empty this can of worms and get on with it.
The address is correct: http://archives.math.utk.edu
Top right, Software section, click "Windows...."
Choose "Graphing programs", and there find Graphmatica.
It's labelled as shareware, but the author generously offers it free
if not affordable.
Click that, then choose grmat16n.zip for the latest Windows version.
It will do for the shop, for the kids in high school, or in college
and university. Type in a function as done normally: e.g. y 2sin(x), no need for 2*sin(x) etc.. You can graph an ellipse as well,
but that can be done as readily, and to scale in a simple but powerful
CAD such as DeltaCad.
Default is a coloured background, and coloured curves, but you can
change that to white. You can do more than one in one shot. Tons
more software there, but not for this forum. I just mentioned it for
anyone wanting some usual or unusual math curve.
Ahh.. thanks. My problem was in using ftp, and couldn't find it in the
directory tree. Turns out Enoch pointed me at it, in a directory
(msdos) that I would never have thought to look in. Anyway, that
pointed me to the author's web site, and I grabbed the latest version
That's a slick little program. Gonna try making some paraboloids.
They are different. You can still as easily plot the catenary though
if that's what you want. Nobody will notice the difference [or be too
interested.] You'll need the parabola if you need a focal point.
Interesting. I was told that a catenary was a parabola. Of course it
was a web page somewhere that told me this, and we all know how
absolutely accurate web pages are. I will need a focal point, so
thanks for the info.
Oleg Lego (in firstname.lastname@example.org) said:
| The Guess who entity posted thusly:
|| On Mon, 20 Feb 2006 12:50:59 -0600, Oleg Lego
||| That was my plan... I only need a few templates to form a
||| framework to be filled. I was going to use the "hanging chain
||| catenary" for it, but this will be easier.
|| They are different. You can still as easily plot the catenary
|| though if that's what you want. Nobody will notice the difference
|| [or be too interested.] You'll need the parabola if you need a
|| focal point.
| Interesting. I was told that a catenary was a parabola. Of course it
| was a web page somewhere that told me this, and we all know how
| absolutely accurate web pages are. I will need a focal point, so
| thanks for the info.
They're actually very different critters, as you can see from the
"shape" of their defining equations (source: Burington's "Handbook of
Mathematical Tables and Formulas") -
Catenary: y = a * (exp(x / a) + exp(-x / a)) / 2
Parabola: 4 * a * (y - k) = (x - h) * (x - h)
For a wine rack, I think I'd want concave circular arcs to support the
bottles - with either a horizontal flat or an ornamental convex curve
connecting those arcs. A repeating ogee might give an interesting
DeSoto, Iowa USA
That was my own thought. I was just having a bit of fun. One of the
best and most practical approaches is to look at where you "think"
you'd like the curve to go, and make a few marks. Then join the dots
with the French Curve. If anyone does get carried away with the
esoteric, and I've seen some fine woodworking that really was a work
of art, they might look here for further inspirationin their "famous
Copy/paste works just fine.
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