CNC newbie questions

Hi all,

I'm about to embark on an investment in CNC and have opened
a can of worms, I think!

I'll be buying a Sherline 2010 mill and proably using
Sherline's steppers, unless somebody on this list advises
me that I need better motors.

I'll either make my own microstepper controller (4-axis), or
maybe will use Xylotex boards.

Now for the questions: (!)

1/ Does anybody consider the Sherline steppers to be underpowered
for the machine? (I assume the main limitation is in the maximum
usable step rate?)

2/ I'm having trouble understanding the power supply requirements
that I've seen documented (e.g. in Gecko Drives' white paper).
Assuming the motor is at rest in the 45 degree step position, where
the motor will need the maximum current, each winding needs to be
powered with Iwinding = Imax/sqrt(2). From this, it would appear
to me that the drive power supply needs to provide an average
current of 2 x Iwinding = 1.4 x Imax
This conclusion doesn't gel at all with the requirements in the
white paper (in that my calcs show a MUCH gruntier supply is
needed), so I'm confused as to where I've got it wrong.

3/ Any suggestions/recommendations as to CNC software? I've looked
at DeskCNC, Mach2 and TurboCNC. Each seems to have ups and downs.

DeskCNC has a serial interface to proprietary hardware, which
appears to avoid PC hardware compatibility issues, and it includes
some CAM functionality. I'm not sure about it's ability to
support 4 axes in either CAM or CNC. I was advised that it does
but the downloadable S/W doesn't seem to.

Mach2 supports 4 axes but may limit my computer installation, since
it needs to do naughty things to get Windows to be pseudo real time.
It also doesn't have any CAM, so I'd need to sort a solution out
there (Suggestions welcome).

TurboCNC gives me the option of using a really cheap PC running DOS,
at the expense of lower step rates. I haven't had a chance to look
at this closely yet - I don't know whether it can handle 4 axis
control.

At the moment I guess I'm leaning toward Mach2, if I can sort out
the CAM issue. Maybe I'll have to bite the bullet and buy
BobCAD/CAM. I have access to SolidWorks so I wasn't really that
keen on having to shell out for a CAD package I don't really need
at the moment.

Any others I should consider?

Thanks for any assistance for the newbie,

John Haddy
Sydney, Australia