CNCing a big surface grinder ?

My friend (no email at home) just purchased a Brown and Sharpe #1
surface grinder, (8x18") 1988 vintage, in excellent shape. For those
not familiar with these units, they are massive, weighing about 4000
pounds and are powered/controlled by a hydraulic system for longitudinal
and crossfeeding. The cross travel for instance is set by a cable which
trips limit switches. The speed the machine operates at is controlled
by flow valves. The Z axis is however controlled by a SloSyn stepper
motor !

Typical of a system of that era, the control cabinet is massive and
contains all sorts of relays and wiring. The spindle motor is 230 or
460V 3 phase, as is the coolant pump and the hydraulic pump. The unit
has an Allen Bradley Variable Frequency Drive (VFD) for controlling the
grinding stone speed. Unfortunately it looks as though it only operates
on 460V 3 phase.

My friend has all the manuals and schematics for the unit and they are
mostly readable.

The grinder is not operational due to a missing control panel.
Physically, the grinder is in excellent shape. The lubricated ways all
look like new, for example. The spindle doesn't appear to have any
wear.

So... my question is this: is it feasible for my friend to replace the
hydraulic control system on the grinder with a PC based CNC control
system and the usual stepper/servo motors, maybe of the multi HP variety,
like some of the high output treadmill motors ? By this I mean
entirely remove the whole hydraulic drive system and use it only with
the PC based CNC system ? On the surface it appears feasible, are there
any potential 'gotcha' issues peculiar to surface grinders?

The table on these units appears to weigh about 200 pounds and rides on
a lubricated way. This unit has a manual feedwheel that can move the
table in the X direction. This feedwheel drives a rack and pinion to do
so. Would it be feasible to power this with an appropriate sized servo
motor ? (The rack bolts to the underside of the table, so it could be
replaced if it wore out...)

The Y axis movement actually moves the entire column, not the table !
It can be manually moved by a feedwheel and acme screw, fairly easily
given the weight of everything. Would it be feasible to drive this
leadscrew with another large servo motor ? I guess the ACME screw could
be replaced by a ballscrew if necessary.

As far as I can tell, the hydraulic motor powering this thing is a few
HP at most. The servo motors we'd use would be large 90V (with Geckos)
or 180V (with Rutex drivers) Baldor or treadmill motors. Can anyone see
a problem with doing this ?

Has anyone already done this ?

Thanks.

Doug















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