Helical ramp problem

Not so much of a ramp problem..more like i'm trying to draw an electric coil that looks like the surface of a carpark spiral ramp..... but the hard part is that the inside edge of the ramp has a sine wave imposed , so that it would be very bumpy on the cars' inside wheels.

The idea is that : all lenghts driven on, ( distance the electrons travel ) are the same.

on the surface ,anyway..and thats where it matters most.

Lenght (circumfrence) of outside diameter per turn = pi X d

Lenght (circumfrence) of inside per turn = same as outside ( cause it's convuluted into a sine wave )

My coil is around 200mm OD , is made from flat copper strip (40mmX1mm) has 67 turns and has 48 waves( cycles ) per turn. I can't figure out how to draw this. We made a prototype by rolling flat allaminium strip on edge thru a set of geared sine wave profiles .

any ideas?

Just a thought, the way I would try to do this is, draw both the outer and the inner of the first wave, centre trough thru' to centre trough.

Connect the two edges to make it a solid 40 mm wide and 1mm thick. Then use a polar array to place consecutive waves in the manner you require. (Rather like positioning treads in a 'spiral' staircase).

Hope this is of help or even a bump to get a lisp genius on the case.:wink:

Thanks heaps Rob-GB..I've now constructed an approximation of what I want. Yet.. far too many vectors , so the drawing is lots 'chunky' and lacks definition.

Perhaps autocad isnt the best program to use for this many curves, or am I still not 'getting' it? I think I will have to learn more about LISP.

regards maxim (re: magnetic cavity resonant field occilator research group)

Your welcome.

Will smoothing help? This is from Acad help, it explains it better than I:-

Arc and Circle Smoothness

Controls the smoothness of circles, arcs, and ellipses. A higher number produces smoother objects, but more time is required to regenerate, pan, and zoom the objects. You can improve performance by setting this option to a low value such as 100 for drawing, and increasing the value for rendering. The valid range is 1 to 20,000. The default setting is 1000. This setting is saved in the drawing. To change the default for new drawings, consider specifying this setting in the template files on which you base your new drawings. (VIEWRES command)

Segments in a Polyline Curve

Sets the number of line segments to be generated for each polyline curve. The higher the number, the greater the performance impact. Set this option to a low value such as 4 to optimize performance for drawing. Values range from -32767 to 32767. The default setting is 8. This setting is saved in the drawing. (SPLINESEGS system variable)

Rendered Object Smoothness

Controls the smoothness of shaded and rendered curved solids. The value you enter for Rendered Object Smoothness is multiplied by the value you enter for Arc and Circle Smoothness to determine how to display solid objects. To improve performance, set Rendered Object Smoothness to 1 or less when drawing. A higher number decreases display performance and increases rendering time. The valid range is 0.01 to 10. The default setting is 0.5. This setting is saved in the drawing. (FACETRES system variable)