We have decided that there are better ways of doing this. You don’t need to gear the shooter twice to get it to speed up faster. How about an adjustable flywheel instead? Plus there really isnt that much of a differance. Ours would go from 3 sec down to 2 sec. That really isn’t that much of a differance when the shooter gets the shots off fine in 6 sec.
We’re using a CIM through a Dewalt for the reasons stated in Andy’s post. The math says it’ll shave about a second off the spinup time. I think the more important feature is that it optimizes the power output to the shooter. Your motor is limited to 40 amps or so, after all. If you gear it low to start out, you can get out of the RPM range where you’re drawing 80+ amps at 12V a whole lot quicker. And you only need to worry about the sequence once if you’re keeping your wheel spun up the entire time. Although I really need to check on the current draw to see if we’ll be doing that.
Our shooter reaches full operating speed in 0.6 second (due to good mechanical design coupled with software control), but we slowed it to ~ 2.0 seconds to reduce the stress on the mechanical system (to reduce the stress on our M.E. really).
I can’t imagine needing to take less time than 0.6 sec. to come up to speed unless you only turn it on to fire. Not much energy gets burned simply maintaining speed though.
We use a single mini-bike motor, 3 gears, 4 pulleys and 2 timing belts, so a shifting transmission and piston would add weight.