RE: [CAD_CAM_EDM_DRO] XY point list for spiral to DXF?

Oh that would be fun - Spirals are generally defined in polar coordinates.
I'd create a spreadsheet that automated the spiral polar coordinates, and
then calculate the rectangular coordinates therefrom. I think Archimedes
grew his spiral linearly, but there are several others...

I'd be willing to help with the SS if you like.

I grabbed the following from
http://www.bookrags.com/sciences/mathematics/spiral-wom.html

Spirals are classified by the mathematical relationship between the length r
of the radius vector, and the vector angle q, which is made with the
positive x axis. Some of the most common include the spiral of Archimedes,
the logarithmic spiral, parabolic spiral, and the hyperbolic spiral.

The simplest of all spirals was discovered by the ancient Greek
mathematician Archimedes of Syracuse (287-212 BC). The spiral of Archimedes
conforms to the equation r = a, where r and represent the polar coordinates
of the point plotted as the length of the radius a, uniformly changes. In
this case, r is proportional to .

The logarithmic, or equiangular spiral was first suggested by Rene Descartes
(1596-1650) in 1638. Another mathematician, Jakob Bernoulli (1654-1705), who
made important contributions to the subject of probability, is also credited
with describing significant aspects of this spiral. A logarithmic spiral is
defined by the equation r = e a, where e is the natural logarithmic
constant, r and represent the polar coordinates, and a is the length of the
changing radius. These spirals are similar to a circle because they cross
their radii at a constant angle. However, unlike a circle, the angle at
which its points cross its radii is not a right angle. Also, these spirals
are different from a circle in that the length of the radii increases, while
in a circle, the length of the radius is constant. Examples of the
logarithmic spiral are found throughout nature. The shell of a Nautilus and
the seed patterns of sunflower seeds are both in the shape of a logarithmic
spiral.

A parabolic spiral can be represented by the mathematical equation r2 = a2.
This spiral discovered by Bonaventura Cavalieri (1598-1647) creates a curve
commonly known as a parabola. Another spiral, the hyperbolic spiral,
conforms to the equation r = a/.

Another type of curve similar to a spiral is a helix. A helix is like a
spiral in that it is a curve made by rotating around a point at an
ever-increasing distance. However, unlike the two dimensional plane curves
of a spiral, a helix is a three dimensional space curve which lies on the
surface of a cylinder. Its points are such that it makes a constant angle
with the cross sections of the cylinder. An example of this curve is the
threads of a bolt.

Chuck Merja
www.3rivers.net/~chuckm/index.htm

Lemelson-MIT Inventeams - http://web.mit.edu/invent/n-main.html

US FIRST Robotics - http://www.usfirst.org/
lat/long 47.52383  -111.67912
211 Adams Rd
Sun River, MT 59483
vx   406.264.5955
cell  406.799.5955
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-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of rutexusa
Sent: Thursday, January 05, 2006 7:35 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] XY point list for spiral to DXF?

Gentlemen,

I tried to make a spiral within Turbocad without success.

So...I plan to write a short basic program to generate an archimedean
spiral with particular dimensions that I want to have waterjet cut out
of sheet metal. Then I will have a list of coordinates. I want to
inport this list to a cadd program to do a little more editing and
which will give me a dxf file ready to cut for the waterjet company.

Does anyone know of a program/way which will allow me to take a simple
list of coordinates and produce a dxf file for input to a cadd
program?

Is there a better way of doing this without buying another expensive
cadd program?

Tom Eldredge






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