This Java applet draws the logarithmic spiral used to make Friend-type camming devices. Enter the pressure angle, the maximum size, & hit the "Draw Cam" button. Both numbers can be integers or have decimal parts.
The output is displayed best if 0 < pressure angle < 90 & 0 < size <5. You can try parameters outside these ranges, but the results may be strange. On actual Friends, the pressure angle is about 14.5 degrees, & the maximum size (of one cam) ranges from 0.2" to 5". The smallest cam that would work with the stem shown here has a maximum size of about 0.55", a little bigger than a #1 Friend.
For the curious, the spiral is given parametrically by
In polar coordinates (r, t), r = Rexp(bt).
The Close Cam & Open Cam buttons do the obvious things. These applets are computation intensive. They may look (more than) a bit clunky on slower machines.