I'm making a wine rack:
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.
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.
| Frank Ketchum wrote:
|| The plans give a link to the pattern that they used
|| Print and attach to the wood!
| D'oh! Must have missed that on the read-through. Boy, is my face
| 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.
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...
DeSoto, Iowa USA
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.
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
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
The results should be as follows:
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
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.
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.
"Then said I, Wisdom [is] better than strength: nevertheless the poor
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.
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.
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.
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.
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