Hi from Brum

[EddyCurrent]

the last reply I think I called you eddy, saw where your nick originates from now so apologies :)

No, Eddy is fine everyone uses that.

1. AMPS - 3x steppers drawing 4.2 amps. 3 x 4.2 = 12.6A
Because running in parallel amps required from PS should be 2/3 of total = 8.4A
Q. I presume it is ok to up to 10A as the drivers will draw what they need?

Yes, 10A will do fine, they will only draw the amps they need.

2. VOLTAGE - [FONT=TTE2325410t00][SIZE=3][FONT=TTE2325410t00][SIZE=3]32 * √L = Vmax
inductange (mH) of 1x stepper is 3.2 +/- 20% so 2.56-3.84mH
using the above, as far as i can see the voltage should be 51.2-62.71V or 57.24V if the stepper is spot on.
Q. So would a 60v 10A PSU be correct? Do i need to multiply the volts by 3 for the other steppers?

If you look at the EM806 spec. it says 68V typical, 80V max so I would use 60 volts as an absolute minimum.
You don't multiply the volts by 3
The best type of supply for this application is an unregulated 'linear' one and best to build it yourself, there are examples of how to do that if you search this forum.

Here's one and the next post down too.
http://www.mycncuk.com/threads/7942-...2015#post62015