is it normal for one motor to run warmer than the other is there normal opeating temp
Each motor temperature could be different ie; depends on the driver amp setting / wiring method for a motor, just how much work it is doing, and also the ambient temperature.
Max motor temp is based on the winding insulation and the manufacturer states what that is or recommends the max amp at a voltage.
My general rule of thumb for steppers ..... if it's too hot to hold your hand on a motor after running for some time ( which would be around 140 degrees F) change you drive amp setting.
You can get burnt at 140F. A stepper can start to behave rather wierd if it gets too hot.
As far as time goes , I have left mine engaged for say 12 hours and they didn't get hot, i have run steppers for 6 hours constant and they were at around 130 deg F with no problems, yet
I have also run them for about 1 hour and they started missing steps, sounding differently, etc. Different steppers ....different temperatures.
Since i have a number of different machines which all use the same controller / drivers a switch box is used allowing me to choose a resistor which changes the driver amp setting.
If you look at a motor curve, which shows torque to rpm at some voltage, the ideal would be to have the amp setting such that you get the max power ( speed x torque ) from the motor.
Above and below that power point is something only you can determine based on desired motor application.
feeds and speeds are way slow
Not considering the mechanical side of your system.........
The feedrate is limited by your max velocity which will llimit your rapid move. The motor rpm can be limited by the amp or voltage being supplied.
An extreme example of this is a low amp setting and the motor won't even turn when pulsed.
Hope the above is helpfull,
RICH