This ought to fulfill my one mandatory post....
  The CNC Mill I have is a Sable 2015 3-axis.  Am just about
finished with the setup portion of installation and was doing
a run check with the "roadrunner" file.  That seemed to
go fine.  It wasn't until after I shut down that I decided to
check the temp of the controller box.... Yikes!  REALLY warm
to the touch... took the cover off and the controller chips were
almost cool to the touch but the 4700ufd caps were warmer than
the heatsink....        Does anyone with a Sable 2015, and the 2nd
version of the controller, have any experience with this?  ((thinking that
maybe the axis settings (i.e. steps, accel, decel) have an impact and
a quick fix))
Thanks...

I'm guessing here, but I think there is a real good chance that the wrong capacitors were used when your controller board was manufactured.  They need to be low ESR capacitors, suitable for use in switch-mode power supplies.

You can probably replace them yourself - Digikey will have suitable parts available overnight.

dwayne

There can be very high current flowing in to large value capacitors, everytime you fast decel the caps are absorbing the back EMF. High current is flowing  in and out of them.
Whether this is normal on this machine, I could not tell you.
Nosmo.
 

...  They need to be low ESR capacitors, suitable for use in switch-mode power supplies....
dwayne

  Yes indeed they do.

There can be very high current flowing in to large value capacitors, everytime you fast decel the caps are absorbing the back EMF. High current is flowing  in and out of them.
Nosmo.

  Thanks for your quick replies.  I appreciate the info...
 So with this in mind, bigger is better with a low ESR, right?  The premise being that those
large currents are more easily handled with a larger capacity.  My original post state 4700ufd but
upon second inspection those caps are actually 2200ufd. (Twenty two hundred, oops   sorry for
the typo). I did go to Digikey and have received some larger caps...  8200ufd (eighty two hundred).
Measured the cap profile and the controller box - if I remove the old ones, it looks like they will just
fit...   Also took a look at the output waveform on a 10Mhz O'scope... and, of course, the waveform
looked REALLY GOOD... hardly any high frequency noise at all...       and then installed a cpu heat
sink and a fan from an old computer to the underside of the controller chips.  I figure that if the machine
is going to be run for a long cut I need to get as much of that heat out of there as I can....  from
what I gather a 'reduced thermal stress' will increase reliability with regard to solder joints, product life, etc..
mk77
p.s.  cant find the Equivalent Series Resistance rating on the caps I pulled out (not on any of the
data sheets that I can find) but the new ones are around Fifty milliohms...