[HammadB]

We found through testing that in terms of maximizing distance and precision it depended on your rpm at wheel. At higher RPM's (I don't recall the exact numbers, I can dig up the data if your interested) we found a grippier material helped to impart spin to the disc (albeit this slowed the disc down due to higher friction). However, we noticed that gripper materials introduced more variability in the system. So we switched to a slower (medium ) RPM and a smooth polished aluminum surface which we put a little graphite powder on. This kept the spin at a high rate and still gave us the distance the higher speeds were giving us.