It will depend on the gearing between motor and screw and the pitch of the screw itself.

I will assume it is a 5 TPI screw rather than metric so that means that your gearing must be 8:1 which seems extreme.

BTW Geckos are 10 micro steps and you can not alter that. Almost certainly your motors will be 1.8 degree which is 200 steps per rev, so for one rev of the motor you need 2,000 steps. Now if the screw is 5TPI then you would need 5 motor turns to move 1 Inch, so that would be 10,000 steps per inch if it was direct coupled, so that is why it seems you have 8:1 gearing as you say it requires 80,000.

Now your Max Velocity, that is determined by the steps per unit and the Kernel you have set, so at 25KHz the max Velocity you would get is 25,000/80,000 x 60 = 18.75IPM

If you increased the kernel to say 60KHz then you would get a max velocity of 45IPM, increased to 100KHz and you would get 75IPM. Be aware though that things may get unstable the higher the kernel you use.

If you can you should look at reducing the gearing, that may not be possible however as it may mean your motors do not have enough torque to move the axis as they are quite heavy on a seriesII.

Hood