Need Help!- Allegro 5804 Stepper IC and EMC2

[GreenLead]

I'm currently experimenting with EMC2 to run a aluminium-working mill.

The control board I am using is CW Tech's 3-axis unipolar stepper control board, based on the discontinued 5804 IC. The only reason I'm still using this dinosaur is because I have some lying around at home

The issue is that while the control board can handle step signals of around 100kHz comfortably, my steppers stall a little beyond a measly 400Hz - nowhere near the kHz EMC2 operates in! In fact, I have only tested the board and steppers at a pathetic 20Hz with EMC2.

I've been considering ballast resistors and increasing the power supply voltage, however:
- My motor is rated at 24V
- The board's 7805 regulator can only handle a max voltage of 35V

I'm looking for the following result:
- 400steps/rev motor, >276 oz-in holding torque
- 20TPI ballscrew
- Half-stepping
- And the goal of 60IPM

Any ideas where I should start?