RE: Fletching arrows, questions
The right and left helical are of a curved, helical pattern. Look directly down the edge of your helical clamp and you'll see the curvature. The straight clamp is just that- completely straight. The straight clamp allows you to put your fletching on straight and parallel with the shaft, or to apply some angled offset by dialing it in with the adjustment knobs on the Bitz.
The straight offset will still give your arrow some spin in flight, yet it may provide better clearance with some prong type of arrow rests.
The helical is kind of adjustable, but it will be very dependent on what diameter of shaft you're using, and the length fletching. There is always some trial and error to find the best fit of the clamp curvature on the shaft for the length of fletching being used, and the amount of helical you're trying to acheive. LIke I mentioned before, it may also depend on how much clearance you have between the prongs of a arrow rest. Once you get used to the Bitz and doing some fletching- you'll see that you can experiment with all kinds of fletching options.
You can put more helical angle or offset with a shorter fletching for a given opening between prongs. A longer fletching won't allow as much helical or offset and still be able to clear the prong opening width.