I've been doing a lot of reading about PSU design but there are still a couple of issues I'd like help with.

Firstly, I've seen some people say that that the current drawn by a stepper is per phase? So if a motor is rated at say 4A per phase its actual requirements might be as high as 8A? Presuming it is of course a 2 phase motor. Whilst I've seen lot's of drivers that can happily supply that amount of current, it does seem to have an enormous impact on PSU requirements, which brings me neatly to my second question...

I've seen differing percentages quoted regarding exactly how much of that current a driver actually uses, AndyUK talks about it being 60-70% but I've read elsewhere that it can be as high as 80%. Obviously this has a significant impact on the design of the PSU, not just on the actual tranny itself but also on the size of the capacitors needed for the smoothing function.

So can some kind soul clear this up for me... when calculating motor current draw, do we calculate the A per phase or not, and what is a good % figure to use for actual driver current draw? OR does this last point very much depend on what drivers you actually end up using? So some might use 60% whereas others will take 80%.

On another note...

I sunk a big chunk of my CNC budget into one of my other loves and bought one of these babies...

https://www.brewuk.co.uk/grainfather-g70.html

It does mean that my hopes for my CNC will be knocked back a bit further but I'm saving a fortune by not going to the pub so the CNC kitty should be back to pre-lockdown levels soon.

Cheers