Build Thread UNIPOLAR DRIVER WITH L297

Hi All
(first thread)
Attached is a schematic (from Design Spark) of, what I hope, will be my driver circuit for a bench top CNC Mill.
I have tested the base circuit and all seems to be ok, I have now added the Vref and Sens1 / Sens2 circuits but as I don't have extensive test equipment nor i high degree of electronics ( basically i'm a hack) , I thought i would ask the forum to view and comment, all feedback appreciated.
I have read the data sheets on the L297 and researched of the web extensively
but my understanding of the chip is basic.
Current control to the steppers is my main concern, as i understand this is controlled by the Vref osc and sens1 and sens2 circuits.

My questions
1/. Is my understanding of the current control correct?
2/. Does the circuit make sense?

Edit note: IRF530 rated at 17Amps 100V diagram is incorrect.


Thanks in advance

Doug

Attached Images

Unipolar Driver V1.1.jpg‎ (193.7 KB)