Lay out a sine curve?

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Brooks Moses wrote:

That's a pretty good idea. Plotting points, but no need to calculate their values.
Josh
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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.
Phil


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Phil-in-MI wrote:

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.
Joe Barta
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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 running.
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.
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The Guess who entity posted thusly:

Sounds interesting, but I have not been able to find it. Is that name correct? If so, would you happen to know what directory it's in?
Thanks.
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wrote:

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.
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The Guess who entity posted thusly:

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 (2.0n).
That's a slick little program. Gonna try making some paraboloids.
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wrote:

That will be difficult, since it's all 2D. I could point to some 3D software, but you still won't get it to leap off the paper. Stick to the 2D and rotate the finished template.
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The Guess who entity posted thusly:

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.
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wrote:

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.
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The Guess who entity posted thusly:

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.
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wrote:

The parabola is a conic section. The catenary's a different ball of wax involving exponentials. Have fun looking into it. I'll end it here.
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Oleg Lego (in snipped-for-privacy@4ax.com) 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 appearance...
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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wrote:

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 curves index":
http://www-groups.dcs.st-and.ac.uk/~history /
Copy/paste works just fine.
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Oleg Lego wrote:

http://archives.math.utk.edu/software/msdos/graphing/grmat/.html
er
--
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you could use something like this:
http://www.leevalley.com/wood/page.aspx?c=1&pQ161&cat=1,42936,42958&ap=1
Christian

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Christian (in zIQJf.32027$ snipped-for-privacy@ursa-nb00s0.nbnet.nb.ca) said:
| you could use something like this: | | http://www.leevalley.com/wood/page.aspx?c=1&pQ161&cat=1,42936,42958& ap=1
You'd probably want to find one with a smaller minimum radius. ;-)
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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Well, thanks everybody for the replies. Apparently there are about 15 ways to skin this particular push stick.
-Phil Crow
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snipped-for-privacy@yahoo.com says...

Well, sort of... This isn't a sine curve, but it's attractive, and easy to lay out with a disk:
http://mathworld.wolfram.com/CurtateCycloid.html
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snipped-for-privacy@yahoo.com wrote:

Found this for ya
http://ferl.becta.org.uk/content_files/ferl/resources/colleges/itchen/filedownload/amulley/SineCurve.xls
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