I have a couple of questions about your motor calculation spread sheet. The motor inertia is input in gm-cm^2 (B32). The rotor inertia given in I27 must be Kg-m^2 since the total inertia is the sum of the screw inertia, load inertia and motor inertia, the others are in Kg-m^2. I27 = G35 which is a lookup to convert units of the motor inertia.
The problem is 1000 gm = 1 Kg and 100 cm = 1 m so gm-cm^2 should be divided by 1000*100^2 = 1*E7 not 1*E8 as in G35. The motor inertia in the sum is 10 times too small.
I cannot find the time used for the acceleration torque (I34). The equation is G32*I28. G32 is labeled as V but it is really the number of pulses/second of the stepper based upon a 200 pulse/revolution motor and the screw speed (which is the Max. linear speed divided by the screw pitch). From looking at the equations, the running torque is small compared to the acceleration torque unless there is a lot of friction in the system. I have not found any references as to what range of acceleration is needed for a CNC. Obviously, when a stepper system is tuned it will limit the acceleration so positioning steps are not dropped due to the loads. Too small motor torque will result in a very slow CNC due to acceleration limitations. At some point a larger motor torque results in small performance gains for the cost increases. Are there any guidelines for this? Thanks.