Lay out a sine curve?

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I'm making a wine rack:
http://www.uniqueprojects.com/projects/winerack/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.
Thanks,
-Phil Crow
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The plans give a link to the pattern that they used
http://www.uniqueprojects.com/projects/winerack/3b.pdf
Print and attach to the wood!
Frank
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Frank Ketchum wrote:

D'oh! Must have missed that on the read-through. Boy, is my face red.
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? I've just received a copy of Autocad 2005, but really don't have much clue as to how to actually use it. I've bought the "for dummies" book, but haven't sat down and dug in yet.
At any rate, thanks, Frank.
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snipped-for-privacy@yahoo.com (in snipped-for-privacy@g14g2000cwa.googlegroups.com) said:
| Frank Ketchum wrote: ||| || || The plans give a link to the pattern that they used || || http://www.uniqueprojects.com/projects/winerack/3b.pdf || || Print and attach to the wood! || || Frank | | D'oh! Must have missed that on the read-through. Boy, is my face | red. | | 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? I've | just received a copy of Autocad 2005, but really don't have much | clue as to how to actually use it. I've bought the "for dummies" | book, but haven't sat down and dug in yet.
Phil...
I use DesignCAD and found that the "curve" (connect-the-dots with a smooth line) function will provide a close approximation when sufficiently many points are provided. I ended up writing a macro to produce a half-cycle cosine curve given the two end points (This gave me the ability to make smooth transitions between two horizontal lines, which was what I really wanted.)
If you'd like, I can produce a full-cycle sine/cosine curve and attempt to export as a dwg or dxf file...
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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Morris Dovey wrote:

Thanks, Morris, but I think I'll just use the pattern in the plans for this one. I do appreciate the effort, though. I guess my post was more in the spirit of knowing how for the next time, rather than having a "canned" curve to use.
Writing macros, huh? Is that a hard thing to do? I can barely draw a straight line with Autocad, so I guess macros are not in my immediate future, but it's good to know that when I get there, there's a utility that will help me out for the next time.
'Preciate the feedback.
-Phil Crow
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snipped-for-privacy@yahoo.com wrote:

You could make a somewhat complicated jig to do it, but it's probably a lot easier to just plot points. First, pick your wavelength (horizontal distance from peak to peak or trough to trough). Let's say it's 6", which is pretty close to what they used in their pattern. We'll call that "L". Then pick your amplitude. That's the height of the waves from the midpoint. In their example, I think the pattern is about 2 1/2" from peak to trough, which means that it's 1 1/4" to the midpoint. So the amplitude is 1.25; we'll call that "A". Then you simply take a piece of graph paper, plug in the formula for a sine wave into a calculator or into a spreadsheet, like Excel, and start plotting points. It's definitely easier on Excel, because you can do it once, and just copy and paste a bunch of times to get the rest of the points. The formula is y = A*sin(2*pi*x/L). If you're calculator is in degree mode, rather than radian mode, the 2*pi simply becomes 360. Just plug in values for x, and plot the corresponding value of y on a sheet of graph paper.
As I said, it's easier in Excel. Here's how you'd do it:
(1) Open up a blank worksheet. (2) In the first cell (A1), put your desired wavelength (e.g. 6). (3) In cell B1, put in your desired amplitude (e.g. 1.25). (4) In cell A3, put in this formula: =(ROW()-3)*$A$1/24 (5) In cell B3, put in this formula: =$B$1*COS(2*PI()*A3/$A$1) (6) Select cells A3 and B3 and copy them to the clipboard (7) Select a block of cells from A4 to B27 and paste from the clipboard (8) Select all cells (ctrl-a), then format cells (ctrl-1). Select the "Number" tab, and force the category to be "Number" with 3 decimal places.
The results should be as follows:
6.000    1.250
0.000    1.250 0.250    1.207 0.500    1.083 0.750    0.884 1.000    0.625 1.250    0.324 1.500    0.000 1.750    -0.324 2.000    -0.625 2.250    -0.884 2.500    -1.083 2.750    -1.207 3.000    -1.250 3.250    -1.207 3.500    -1.083 3.750    -0.884 4.000    -0.625 4.250    -0.324 4.500    0.000 4.750    0.324 5.000    0.625 5.250    0.884 5.500    1.083 5.750    1.207 6.000    1.250
At this point, the first column is a list of x-values ranging from 0 to 6 (in 1/4" increments in this particular example). The second column is a list of corresponding y-values ranging between -1.25 and +1.25. Just plot this pairs of point on graph paper, connect the dots, and cut out your pattern. You could also create a scatter plot in Excel and experiment with the page scale until you can print it out at exactly 1:1 scale.
You may notice that I chose to use cosine, rather than sine, in my formula. Either one will give you the same shape in the end, but a cosine curve will start and end at a peak, whereas a sine would start and end at the midpoint.
Josh
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Josh wrote:

Thanks, Josh. Scuse me, I've got a spreadsheet to build.
-Phil Crow
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snipped-for-privacy@yahoo.com wrote:

Sure, most CAD packages can do curve fitting or there not very much "CAD." I do it in turbocad. However, historically the problem with Autocad is that its more of a workbench. Its a corporate product and lots of the nifty features come in add-ons that you also have to pay for. But this particular feature should be built in. It may not be tweakable by the parameters you wish to tweak, but it can be done.

--
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"Then said I, Wisdom [is] better than strength: nevertheless the poor
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You can lay out a curve like this in Autocad just fine though, in Turbocad, you can edit the shape in ways Autocad can't.

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snipped-for-privacy@yahoo.com wrote:

You could plot points on paper for 0 to 90 degrees, connect the dots with a french curve, cut it out and use it as a template, flipping it from right-to-left and upside down as needed.
--

FF


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wrote:

Get Mastering Autocad by George O'mura. Autocad 2005 is a state of the art cad program. You need a good source of info. You probably can find a lisp routine using Google that will draw it. I suspect Mathcad could draw it.
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SNIP

As I thought, the link will lead you to a free lisp routine.
http://manufacturing.cadalyst.com/manufacturing/article/articleDetail.jsp?id 0513
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You're kidding, right?

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Nope, not kidding. Been using it for 25 years, make my living with it. I have a legal seat on my home computer. I know what it can do.
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State of the art as long as you don't compare it to Inventor, Alibre, Solidworks, Solidedge, Catia, Mastercam, Surfcam, ect, ect. AutoCAD survives for two reasons, name and the fact that a great many people don't need the power and flexibility that other programs provide. In the industry I'm in, aerospace, AutoCAD has long been a has-been. Seen from time to time but generally only in low level support roles.

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wrote in message
Well, one thing is for sure, neither of us is going to change the others mind, and this is a ridiculous exchange. I don't know why anyone needs cad to draw a sine curve anyway. :-) OBTW, my quartersawn white oak rocking chair is coming along just fine.
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LOL. Well if it is there why not use it. ;~)
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If this thread is about making support cutouts for wine bottles, I believe you should be talking ellipses or parabolas, not sine curves. Much simpler formulas too. Bugs
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Perhaps Arcs rather than an ellipse. An Ellipse is very much like a sine curve/wave.
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Sine curves don't faintly resemble the conic projections, ellipse and parabola except that they are all curves, which includes an infinite family of exponentials, logarithmic, etc. etc. Since wine bottles are basically cylinders, the family of conic projections will fit them precisely. If you want some air space between the bottle and rack, then almost anything should do. Those interested should open a book on analytical geometry. Bugs
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