[Ether]

Originally Posted by Gunnar Frahm

The motors are connected to the same shaft on opposite ends that is supposed to rotate the arm. When the motors run at 100 percent to rotate the shaft one turns at 62 rpm +/- 3 rpm and the other runs at 65 +/- 3 rpm.

1) Where are you getting these numbers from?

2) 62 rpm +/- 3 rpm and 65 +/- 3 rpm share a 3 rpm tolerance band. They may in fact be spinning at the exact same speed. Do you have any other physical evidence that one motor is spinning faster than the other? See #3 below.

3) If the two motors are connected to the same shaft, it is not physically possible for them to spin at different speeds unless the shaft is actually twisting or a belt or gear is slipping.

4) 65 rpm is approx 360 degrees per second. How long is the arm that's connected to this shaft?

So, when I move the arm the slower motor drags the other one behind.

If both motors are functional that's not an accurate description of what is happening. One motor may be carrying a bit more load than the other, but it is not "dragging" the other motor.

The arm we are trying to rotate has to be able to lift a lot of weight, so it is a problem when the motors fight each other.

One motor may be carrying a bit more load than the other, but the motors are not "fighting" each other: they're both contributing torque to lift the load.

I saw something in other threads about calibrating speed controllers. Can you do that with Talon SRX's? We use talons utilizing CAN bus for communication.

Calibration is for PWM. If you're using CAN you don't need to calibrate.

I don't know much about master and slaves. But would that setup work with the two motors instead of PID control?

EDIT: saw your 4th post

Using separate PID for each of two motors which are physically connected is probably not the best way to do it.

If the motors are physically connected to each other (as yours are), using master/slave may be appropriate. But this will not solve the problem you have described (excessive loading and shaft bending).