are you required to use the sprockets (the one that goes on the shaft of the motor assembly) that come in the kit? can you use slightly larger ones with set screws already in them? 
You are under no obligation to use the gears, sprockets, or transmissions that come in the kit. You may exercise a great deal of creativity in these areas… and many teams have. You can build your own, or there are also many parts suppliers who can provide alternative parts.
You are limited to the motors in the kit and the pneumatic and control components in the kit, plus approved additions (but not alternatives) as described in the manual.
If your team is designing a robot and has not read every line of the manual, particularly section 8, “The Robot”, then you would be well advised to go over it closely, watch the team updates, and keep an eye on the Q&A forum.
It is always distressing to see teams show up for Tech inspection on Thursday who are too large, too heavy, using illegal components or undersize wiring. It takes a few hours to carefully read the manual, but it saves a great deal of pain and frustration on Thursday at the regional.
If you have read the manual and are “just checking”… fair enough, but it is difficult to tell that based on your question.
Good luck with your designs,
Jason
Thanks for the help and yes I have read the manual. I just wanted to make sure we weren’t doing anything wrong before we used alternative gears.
By the way there is an expression that has not been used around here in a while, but I remember it from my first Kickoff, back when you HAD to go to Manchester.
“Set Screws Inhale Audibly” (they suck)
If you are just using the set screw to hold a key in place then things will probably work out fine. But if you are trying to carry the torque from the gearbox with the setscrew then you are in for big problems. Teams doing this was a major issue back then.
Hey guys… Can we use the gears from last year? (Not for driving the robot but for other purpouses) ?