![Grinder restored](/amillar/wp-content/uploads/projects2008/20080113_grinder_IMG_0498.jpg)
I received a Baldor metal grinder with 10-inch wheels, on its own pedestal floor stand, discarded from a school metal shop program. Several owners before me did not know what to do with it, mainly because the motor is wired for three-phase industrial power which is not found in U.S. residential homes. My job was to fix it up and get it working.
There were two major tasks to the restoration: cleaning/repainting, and making the three-phase motor work.
Cleaning and Painting
I started the cleaning process by removing all attachments that I could, including the wheel shroud side covers, the wheels themselves, and all electrical boxes and covers. I remove all of the old flaking paint and minor rust spots using a wire wheel brush on the electric drill. Some of the paint was still good, but much of it was stripped down to the bare metal. I could not remove the riveted-on motor label and didn’t want to paint the wheel axles, so I covered them with masking tape.
I spray painted the entire grinder and all the separate parts with primer for a good base coat. I followed it with a few coats of grey paint.
![Stripping paint and rust](/amillar/wp-content/uploads/projects2008/20080101_grinder_IMG_0430.jpg)
![Priming parts](/amillar/wp-content/uploads/projects2008/20080101_grinder_IMG_0433.jpg)
![Painting parts](/amillar/wp-content/uploads/projects2008/20080101_grinder_IMG_0435.jpg)
![Priming body](/amillar/wp-content/uploads/projects2008/20080101_grinder_IMG_0438.jpg)
![Painting body](/amillar/wp-content/uploads/projects2008/20080105_grinder_IMG_0441.jpg)
![Polishing hardware](/amillar/wp-content/uploads/projects2008/20080106_grinder_IMG_0442.jpg)
I cleaned up the hardware to make it look a little nicer. I filed and sanded the heads of the screws and bolts while spinning them in the drill press. I buffed all of them with a cloth wheel, which made them nice and shiny. I finished it with some clear spray varnish.
I reassembled all the pieces, back in the order they came off.
![Painted well](/amillar/wp-content/uploads/projects2008/20080106_grinder_IMG_0468.jpg)
![wheel reinstalled](/amillar/wp-content/uploads/projects2008/20080106_grinder_IMG_0469.jpg)
![Shiny screws](/amillar/wp-content/uploads/projects2008/20080106_grinder_IMG_0471.jpg)
Electrical
Originally this grinder was hard-wired to the wall using “BX”-style flex conduit. There was a power relay and circuit breaker box, which engaged and disconnected all three phases in sync, using start and stop push buttons.
For the 3-phase power, I built a
static phase converter using capacitors.
I rewired the relay box to supply single phase power to the phase converter. I attached it to the pedestal stand of the grinder. I drilled holes in the pedestal and tapped screw threads into them, and screwed the relay box in place. Instead of flex conduit for the power line, I added a standard power cord. Since it uses 240 volts, double the US standard, I used a different plug and outlet.
The phase converter needs an extra momentary push button to start the motor, so I added that to the front of the grinder next to the main on-off switch.
![Tapping holes](/amillar/wp-content/uploads/projects2008/20080101_grinder_IMG_0431.jpg)
![Switch boxes](/amillar/wp-content/uploads/projects2008/20080106_grinder_IMG_0444.jpg)
![Converter and relay boxes](/amillar/wp-content/uploads/projects2008/20080106_grinder_IMG_0445.jpg)
![Relay](/amillar/wp-content/uploads/projects2008/20080106_grinder_IMG_0446.jpg)
![Power to relay](/amillar/wp-content/uploads/projects2008/20080106_grinder_IMG_0459.jpg)
![Start button](/amillar/wp-content/uploads/projects2008/20080106_grinder_IMG_0465.jpg)
![Converter in box](/amillar/wp-content/uploads/projects2008/20080109_grinder_IMG_0476.jpg)