Sorry for the interruption.[:' (]

If you look at the cable track, you can almost tell what kind of draw the cam will have. When I got home, I looked at the Bowtech Pro 38 cams and the Black Knight cams on Frankenstein. On both, the cable track comes to max radius pretty soon, then flattens out, then drops back quickly to the flat which is the valley, where the cam track radius comes almost right up against the axle. The Pro 38 is actually a little rounder at the start of the draw curve than the Black knight. IMO, the shape of the cable track is the most important factor in determining the draw curve. In comparing the hatchet cams I have with the " Strother cams" , the hatchets have the large sweep of the string track which comes into play when you draw into the valley and the cam track is 1/8 - 3/16" from the axle at its closest point. This give it 65% letoff. The Strother cams do not have as much string track increase as the hatchets, but the cable track is much closer to the axle. On the BK cams, you can actually see the axle in the cable track at the valley. The hatchet cams cable track is generally rounder in shape than the BK, and the maximum radius from the axle is 1.5" . The BK is more square in shape, and has a max radius of 1.8" or more. The
BK' s pull in more cable, move the limbs more, and gave my bow close to 10# more draw weight at similar brace heights.

I know that you can control the draw curve with the cable track alone, because I built a small bow for my twins before they were big enough to pull the shortest kid' s bow available at the time. The bow had concentric wheels, and was like an old Martin Kam-Act, except that it only had one cam, and one limb. I had it set up with various cam " modules" that gave us anything from a 12" round wheel draw, to an 18" hard cam draw. The 18" hard cam was pretty fast for a kids bow, and still had 60% letoff even with the concentric wheels. The cams were made of plexiglass, and we actually had a Seneca bow that had a plexiglass " Max Cam" with a matching idler wheel.

Twins are much simpler of course, since you only need to match the two cams. With singles and hybrids, the whole thing gets much more complicated, at least to design and make.