RE: [CAD_CAM_EDM_DRO] CNCing a big surface grinder ?

Alternately, what's the feasibility of spending a few bucks on
electrical hydraulic valves? You'd still need some form of encoder for
positional feedback, but no need to tear into the treadmills.

-e

> -----Original Message-----
> From: Doug Fortune [mailto:pentam@...]
> Sent: Thursday, November 06, 2003 9:50 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] 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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> .
>
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