I've got a torque problem. Let me break it down. i've been researching for hours and don't want to commit to calculations without knowing if what I'm doing is 100% accurate. I need to calculate torque, and then based on the torque from a motor, I want to calculate the coefficient of friction for the surface area in contact with a rotating cylinder... roughly .300" in contact with the cylinder. The shaft is rotating by a DC motor which turns at 1725rpm @ 90v. We've got it clocked down to 1500 rpm through a DC motor speed controller. It goes to a gear box (5:1 ratio) which clocks down the shaft rotations to 300rpm. There is a driveshaft, more or less, that allows a large cylinder to be incorporated into the middle of this... about 4" in diameter. It rotates, and 6 samples with a known load of 2.84lb are forced into the spinning cylinder, - .049" in surface area each. How do I find torque of the shaft? I know my RPMs, my motor is 1 HP and operates at 1725rpm natively, with a F/L torque of 586 oz-in. I want to get torque on the shaft @ 300rpm after the gearbox, and then apply the load and calculate the extra torque needed to spin the shaft after the loaded samples are applied to it. I need: Torque before a mass is applied to the rotational system, Torque after the mass is applied. and the CoF of the material. I feel like I can use amperage and voltage through the motor to get power, but I'm not positive if its correct... I'm also assuming a 20% loss in power through the right angle gearbox and friction from seals and bearings, etc. Thanks!