Which drive for Powermax II steppers
I've been reading a lot, but still have some questions. So here my first post on this forum.
My goal is a CNC-mill, probably based on a conventional mill like the sieg X-1, X-2 or X-3, depending on budget, and minimum size needs. But my approach is a bit unconventional, because I plan to do the stepper electronics first.
I have 4 Powermax II P22NRXA-LNS-NS-02 steppers, wired bipolar/parallel(197 oz in). I have been reading a lot on which driver to use, but the main problem is that integrated driver IC's do not exceed 4A current (L6203 i.e.). Higher current solutions use discrete H-bridges, which are more complex from the circuit design point of view. The steppers have a max current of 6.5A.
What would you suggest using for driver? I would prefer a home build driver. It is a hobby . Is a L297/L6203 based solution sufficient for most uses, or do I really need a driver which can supplie 6.5A? Or can I use the L298 in parallel? In the graphs in the spec sheet the used Voltage is 67V. Should I design my driver and power supply to be able to provide 70V@6.5A per motor, or is this really overkill?
Is it possible to run the integrated circuit bridges over their rated currents using efficient forced cooling?
I have ordered a L297 and a couple of L6203's to start experimenting. But any input is valuable. I plan to design the PCB using EAGLE 4.13.
I understand that I should know the way I will be mounting the motors, what reduction I will apply and what material I would like to mill before the necessary power can be calculated, but a rough estimation will go a long way.
So, any suggestions about my future drivers?
Use the L297 to drive Mosfets Via pnp/npn transistors.
I have had no problem with my home made driver
Also by using a 555 timer driving a small FET you can switch between resistors connected to the Vref pin this enable you to alter the PWM giving reduced current when not stepping. this stops the Stepper getting over heated.