CW? CCW? I am unfamiliar with these terms, but I think I understand what you mean.
Also, I'm going to have to learn some math. I recognize the term done, but would be unable to define it or determine what it is.
Sorry.
CW = ClockWise.
CCW = Counter-ClockWise.
SIN means Sine.
COS means Cosine.
The Sine of an angle varies from 0.000 to 1.000 as the angle varies from 0 to 90 degrees. And the Cosine varies from 1.000 to 0.000 at the same time. At 45 degrees, they are equal. If you start with your compound pointed straight across the bed with its dovetails parallel to the cross slide dovetails, on some lathes (including all Atlas machines) the witness mark on the right side of the compound swivel will line up with 0 on the scale engraved on top of the cross slide. And the scale engraved around the right side of the cross slide compound pivot point would read from 90 on the back side nearest the line connecting the center of the spindle to the center of the tailstock (variously called the axis, spindle axis, machine axis or work axis) down to 0 at the right side witness mark and then back up to 90 on the side nearest the operator. Dave's machine is apparently different, but if you advance either the compound or the cross slide 0.010", the cutter will move 0.010" toward the axis.
If you rotate the compound CCW (counter-clockwise,) so that its back side moves around toward the headstock, and stop and lock the compound when its witness mark lines up with 30 on the scale, advancing the the cross slide 0.010" still advances the cutter toward the axis by 0.010". But advancing the compound by 0.010" moves the cutter both toward the axis and toward the headstock. For 0.010" compound advance with the compound set at 30 degrees as just defined, the cutter will move toward the headstock by 0.00500" and toward the axis by 0.00866".
The practice of setting the compound around to 30 degrees grows out of the fact that the included angle of UNF and UNC and some other threads is 60 degrees. So each side of the thread is laid over 30 degrees from the cross slide dovetails. If you were cutting BSF or BW/BSW (Whitworth) threads, the magic numbers would be 55 and 27.5 degrees. Anyway, only the finest of threads are cut in one pass. So after you have zeroed everything and are ready to start cutting a thread, you advance the compound (not the cross slide) by however much is appropriate for the material and the cutter that you are using and take your first pass. At the end of the pass, you disengage the carriage drive, stop the motor if you want to, back the cross slide out enough that the cutter won't drag on the work, and crank the carriage back to the right, return the cross feed to zero, and advance the compound by however much you are using. And take the second pass.
The reason for setting the compound around to 30 or 29.5 degrees is that the carriage drive system inherently has back lash. Even on a new lathe, if you engage the carriage drive with the motor not running and push and pull on the carriage, it will move a little (or if badly worn, a lot). When turning toward the headstock, only the left side of the cutter is engaged. It takes force to make the cutter bite into the work and the reaction takes all of the backlash out toward the tailstock. By rotating the compound around to 30 or 29.5 degrees, all or most of the cutting is being done by the left side of the cutter, again taking out all of the backlash toward the tailstock. If you advanced the cutter into the work using the cross feed, an equal amount of material would be removed from both sides of the cut. This would be an unstable condition and you could expect chatter and poor surface finish. The reason for using 29.5 (or even 29) instead of 30 degrees is because the scales and witness marks aren't always that accurate. So you want to be removing a little bit on the tailstock side of the "V" to ensure that the thread finishes up as a symmetrical "V".
I see that as usual, I got carried away. Most of you probably know all of this. But I spent the time to write it, so I guess I'll post it. And hope that I didn't make too many mistakes.