I guessed there must be a long-hand method of drawing these shapes.

The 'cone-layout' program was developed for making the intricate exhausts on 2 stroke racing motorbikes.

I started building pipes when I was 18, and learned how to draft all the patterns before

I learned the easy way. But drawing cone patterns by hand is easy.

1). The easiest units to draw cones is millimeters.

2). Draw out the actual cone. Don't worry about scale, but 1:1 scale does make laying

out the pattern easier.

3). Big end - small end = difference.

4) Difference / Length = cotangent

5). Cotangent * big end = point (radius).

6). Use a ruler or 1/4" wide tape measure to draw the length of the cone, mark the

big end, and small end from the point.

If you made your cone to scale, draw 3 lines, the center and 2 sides. Depending on

your accuracy the length of the cone will be the same as #5.

7). Use trammel points or a compass to draw the big end and small end arcs from

the point

8. Calculate the length of each arc (pi * big or small diameter) and measure the

arc with a flexible metric ruler. I still use a 1/4" measuring tape with inches and mm's.

9). Use a straight edge to line up each side of the arc using the 3 points (the big end,

small end arcs, and the point at the top of the cone). If all 3 points line up on each

side, your cone pattern is perfect.

If you are not worried about perfection. Measure the big end arc, and draw a line

using the 2 points (top of the cone to one side of the big end arc).

Bill M.