I got my Bridgeport Boss Hillbilly BOB retrofit going with Mach3, but before I start cutting metal, I would like to have a knob-controlled feedrate override. I used that as a safety device with the Boss controller, and I hate to give it up. I've been playing around with a USB gameport adapter, keygrabber, and a potentiometer. XP will calibrate the potentiometer, but the problem is that Mach3 doesn't seem to pay any attention to the calibration. The effect on FRO only seems to be dependent on the potentiometer maximum resistance. Higher values give more effect on FRO, and lower ones less. Does anybody know anything about this? Incidentally, in case it makes any difference, I'm using an Thinkpad 770e, with ACPI turned off. It drives the system very well. I've played around with the USB adapter and pot on other computers, and it doesn't seem to be any better.