Re: speed vs torque graph for stepper?
A simple way is just to look at the amps draw.
If you have a 425oz and it runs 3A it is high inductance and will be weak at high speeds unless you hit it with 80V.
If your Nema 23 is 5A then it will be faster.
All the stepper and driver behave the same way. They loose power at high speed. I have found that you almost always you want the higher amp steppers for speed.
Luckily with most setups and slower spindles you don't need really fast steppers.
youtube videos of the G0704 under the name arizonavideo99