Re: [CAD_CAM_EDM_DRO] Re: Spindle Motors

Andrew Werby wrote:

>
> [I've got a Rockwell/Precise spindle too, and I was wondering about how to
> slow it down. Are they all 2-phase? Would a regular cheapie "router speed
> control" work, or would that lose all my torque? Care to share anything
> about your drive design?]

The original Precise spindle had a universal motor, the speed
controller was a plain Variac in a box. Mine still has the
cutouts on the main housing for the brush covers, and the scroll
case for the spindle-driven cooling blower. If yours just plugs
into the wall socket and runs, that's what it is. Get a 10 A
Variac and you've got your speed controller!

My drive design will use my CNC stepper/servo controller board
with a different program to generate two-phase PWM waveforms
that carry the two shifted sine waves to my PWM servo amps,
which will need to be tweaked a bit for more voltage, less
current. I have written all the VHDL code for the PWM
generating, but haven't tested any of the code. I still need to
add some acceleration/deceleration functions to it.

When they went to the AC spindle, they switched to a separate
cooling blower, too. This makes a lot of sense, as a larger
blower running at a more reasonable RPM would be more efficient,
and it allows all the motor's power to go into the tool.

As far as I know, all the later Precise spindles are 2-phase, AC.

Jon