Lay out a sine curve?

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Except that ellipses have curves with more than 1 radius similar to sections of a sine wave.

Which is why I indicated an arc will fit more closely fit or follow the shape of a bottle than an ellipse. An arc is a section of a circle. An ellipse is a circle illustrated in isometric or 3d format.
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snipped-for-privacy@yahoo.com wrote:

Generate a sine function in a spreadsheet, plot it on a chart, print it out.
y=h*sine(x)
y: output value h: height of the spline (above and below zero) x: input in degrees
Chris
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snipped-for-privacy@yahoo.com (in snipped-for-privacy@g14g2000cwa.googlegroups.com) said:
| However, the question remains--what if I wanted a curve with a | different amplitude or wavelength? This template idea crossed my | mind, but how to generate such a curve? Can Autocad do it?
This is the easiest part of all. Draw a sinusoid (a sine or cosine curve) with any amplitude or wavelength, then stretch (or squash) to the amplitude and wavelength you want. Copy and paste as many cycles as you want.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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snipped-for-privacy@yahoo.com wrote:

Well, you could do what they suggest in the plans:
"You can use the pattern that we used by printing it out and transferring it to the wood in succession until you have the desired number of holes."
--
Regards,
Doug Miller (alphageek at milmac dot com)
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On 18 Feb 2006 06:59:47 -0800, snipped-for-privacy@yahoo.com wrote:

For future reference, if you want a real sine curve, and not an approximation [within the bounds of the tools and shaky hands] use a math program like Graphmatica, then copy/paste into a word processor or image editor for printing to the scale you want/need.
Graphmatica is shareware, but free for those who can't afford it [so just use it if you can't.] PhotoFiltre , or "The Gimp" are freeware image editors. OpenOffice is a great free office suite with a wordprocessor and spreadsheet and much more.
If you do it intelligently, you can do it to suit your project scale. One hint: in Graphmatica type in y = sin(x) for the unit sine curve, and you might want to change the default colours to black and white. You can change the equation if you want varied results; something like y = 3sin(x) or y = sin(3x) or whatever. You likely don't need that though.
Or, any basic trig text shows how to draw it from the unit circle.
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What's the chances of someone throwing his wine rack up on comparator and measuring the frequency and amplitude of it. The man said he had AutoCAD. Those curves can be drawn in about a minute. Close enough for a wine rack.
wrote:

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That's what I was going to suggest. It's easy, and you can easily scale the sine curve as large or small as you like by choosing an appropriately-sized circle. Since all that's required is a compass and straightedge you don't even have to leave the shop.
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Guess who (in snipped-for-privacy@4ax.com) said:
| Graphmatica is shareware, but free for those who can't afford it [so | just use it if you can't.] PhotoFiltre , or "The Gimp" are freeware | image editors. OpenOffice is a great free office suite with a | wordprocessor and spreadsheet and much more.
Wow! I downloaded Graphmatica and _really_ like it. Wish I'd had something like this when I was in school...
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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wrote:

Perhaps your kids can use it ..or theirs?
It's mostly math, but anyone doing wood modelling can find a use. A parabolic arch is the best support [to do with the focus], so would make a good support for benches, tables, and so on. CAD will draw the circle and ellipse, but I don't know of one that will draw a parabolic curve. There are always layout methods, which were likely used in the past [e.g. by the Romans] since the computer wasn't available way back then. Layout is still generally the best if not too tedious, and I'm not sure yet on the best way to get a printout to scale for a large project. I'll work on that, or offer something about the layout procedure. ...in time; too busy right now.
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Draw, Point, Multiple Point, enter co-ordinates of one point (x,y) and press enter, repeat for all points
Draw, Spline, select all then points you made
To make sure your cursor knows how to find these co-ord points you created. (They will appear as dots), go to
Tools, Object Snap settings, select nearest, under running object snap settings.
I always go to Tools, Object Snap settings, and check endpoint and intersection. In combination with the pick box size it tells the software what to do. Actually just to make changes. Many things like this can be saved.
-
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press F2 to see the commands/ review the co-ords you entered. F2 again to close the window
-
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if you enter the co-ors in the size you need
File, Print, select extents, deselect scaled to fit
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do a FULL preview to not only see the outline of the objects, but the actual innards. Select each time. Multi-preview before printing.
-
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if it takes up the whole page, but in the wrong direction, change the rotation 90. Thats for scaled to fit. origin is if it is offset, integral with the other print settings required = to center it, for instance
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Why go to that much trouble entering coordinates? DDE/Direct Distance Entry would be much simpler and faster
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well thats helpful
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Your welcome.
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snipped-for-privacy@yahoo.com wrote in

In the days before computers and fancy stuff, we used nails, sheet metal or thin wood. Layout the points of the peaks and valleys (or wave points if you prefer) and spot a 4d nail at the point. Take the sheet metal ( 1" wide x 20 - 24 ga. ) and weave it through the nails. Trace the pattern and now you know the rest of the story.
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On 18 Feb 2006 06:59:47 -0800, snipped-for-privacy@yahoo.com wrote:

Make a template. Lay out a grid. Use a spreadsheet to plot points. Use a French curve to connect the dots. Read up on how to use a French curve.
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snipped-for-privacy@yahoo.com wrote:

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
--
The "bmoses-nospam" address is valid; no unmunging needed.

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