CNC ELECTRONICS Power Supply

[JAZZCNC]

I have found that the [FONT=arial]Leadshine DM856 CNC Driver Digital Hybrid Stepper Drive 80VDC/5.6A driver would be the best one for the job as it would allow me to run the stepper motors very fast.

When you say "very fast" what speed are thinking you'll get.? . . . . . Steppers in general don't spin very fast or should say are not much use spinning very fast. Much above 800-1000rpm and they lose fair amount of torque which drops off to nothing very quickly above 1200-1500rpm and at 1500-2000rpm there's next to nothing left.
Speed you get from steppers is mostly down to voltage so is proportional to the voltage provided to the drives and why Eddy current suggested 70vdc but there are limits and for these motors 70Vdc is close to the Max not the minimum. Running at 70vdc is considered working above the design threshold but in practice they handle this no problem and are reliable but going higher can produce excess motor heating which will shorten there life.

Also Be aware that Steppers produce Back EMF so are effectively dynamos when deaccelerating so you need a safety margin between voltage supplied to the drives/motors and the drives maximum voltage rating. Now how large a margin is slightly affected by the type of supply you use and it's for this reason why Unregulated Toroidal supplies are best because they absorb back EMF better thru there capacitors. So if using Toroidal setup you can effectively run closer to the drives Max voltage limit
Now That said even with Toroidal PSU the Maximum voltage I'd run is 75V on 80Vdc drives and for best balance of speed/motor heating and drive/motor life expectancy then I would run that at 70Vdc which is what I consider there MAX sensible working voltage. They will run higher but you'll kill them quicker.

Regards the drives then the DM856 are good drives but because your going to slave 2 motors to one axis then I recommend you go for the better EM806 or AM882 as they have stall detect and fault output which you can use to E-stop the machine if one motors stalls and the other doesn't which if your wanting high motor speeds there is a high probabilty will happen.!
I'll just point out that if your wanting high traverse speeds Ie Rapid speeds or cutting speeds then the correct way to achieve this is by selecting the correct linear setup Ie: screw pitch etc not soley using motor speed. Motors give a certain amount of torque on a RPM curve so matcing the screw pitch to give the speeds required at certain RPM/Torque is the way to do it not just find fast spinning motors.