This is a trial run of the chain drive on the PIE 2.0. The PIE needs a positive drive that will not slip and #40 roller chain is the current choice for this non-slip drive mechanism. Slippage, even extremely minor slip, causes variations in RPM which causes unpredictability in the PIE's performance. Low speed on the drill is rated at 400 RPMs, & high speed is 1500 RPMs.