Any idea what bench grinder I have?

I just picked up an old bench grinder for $10 and I have not been able to find anything definitive after hours of searching online. It's an oddball for sure.

I've spent the past few nights disassembling and cleaning the crud off, hoping to uncover something that will give me a clue. The only thing I've found on the motor itself is a stamped/engraved K5. It's on the stator housing and it's very small.

I think it's a General Electric motor because the mounts for the two capacitors had stickers that read:

General Electric Capacitor
Cy 60
uF 7.5
US Pa 1850702
Schenectady NY 330V AC

The patent number is for capacitor paper from the 30's.

As I said there were two capacitors mounted to the motor.

On the sticker of each mount (same sticker referred to above) is the following:

2 1F2 12 X
and on the other...
2 1F2 12 Y

Searching turned up nothing about these capacitors.

Based on some general wiring research, I believe the motor is a 3 phase AC motor that was delta wired to run single phase. It runs on 115 when I plug it in with the slightest manual turn of the shaft. I can make it spin CW and CCW by starting it either direction. I've read that this is indicative of a 3 phase motor wired to run on single phase.

There are only 3 wires coming out of the motor. They each have small crimped brass identifiers on them. They read T1, T2, and T3.

That is about everything I know. I'm really curious about this machine. Any ideas? Here are some photos.

more pics

The main power switch is an old ceramic rotary PERKINS switch. I haven't seen a grinder with a switch like this anywhere online.

Welcome to the forum, OneSquareLight.

Now, I'm going to tell you some things you may already know!

GE sold both motors and capacitors as separate items and of course as combined items, so you can't be sure it's a GE motor just because it has GE capacitors. Further, you've more-or-less determined that this is a three-phase motor to which someone added the capacitors, so the relationship between GE capacitors and that motor is very weak.

FWIW, the switch looks sort of "pre-1900" to me.

You've presented the case as a three-phase machine adapted to use single-phase. This may very well be correct. If so, the single phase switch and the capacitors are part of the adaptation. Clever people will use whatever is at hand to perform low-budget conversions like this!

None of the photos show any guards or tool rests. If you have these. please post photos as they may help the forum to recognize your machine.

P.S. Perkins Electrical Switch Corp, founded 1895 (!) is still listed at 26 Cortlandt St. in lower Manhattan, NYC. That's a pre-war office building. The address may simply be a corporate lawyer's office......
The Perkins Electric Switch Manufacturing Company in New York, NY - Reviews - Bizapedia Profile

John Ruth

You make a good point. Assuming it's a GE motor is a stretch. The switch, capacitors and the second small toggle switch (did not take a picture of that one) are all parts added for the single phase conversion and likely just parts someone had lying around. My hunch is that the entire unit is a Frankenstein.

The motor itself is odd in that the left side looks like someone cut off the bell. You can see how it's flat compared to the right side. There is evidence of significant grinding on the left side as well though it's not apparent in the photos.

The left shaft is considerably larger than the right and the inner stabilizer is permanently affixed to the shaft. The right side just has a slight lip on the shaft that the inner, removable stabilizer seats against.

There were no guards with the unit. Well actually there was a sheet of plexiglass attached to a frame hovering over the entire grinder.

The rests were quite substantial. However, they were not the same and left was affixed in a different manor than the right. I'll take a few more photos, but I fear that these too are parts that the builder had lying around.

I suspect that this motor was originally used in an entirely different application. This would explain why researching grinders has turned up nothing. I started to look for motors from the 30's and 40's to see if if I could find one that resembled what I have. I did find one motor that sort of looks like the rounded side of mine. It may be quite common design but the holes on the side of this Walker-Turner motor look as close to what I have as anything so far. WoodNet Forums: Restoring an Old Electrical Motor Please excuse the link to another forum.

If someone did manage to put this puzzle of a grinder together out of spare parts, they're nothing short of a genius in my opinion.

The motor runs great. I'd like to know what HP it is, though once I get it cleaned up and get some new stones on it, knowing that won't matter much, so long as I can sharpen my chisels. I guess even if I don't find out what I have, this was just as much about taking the opportunity to share this unique old piece of history.

Here is a better picture of the left side of the motor. Looks like it was all ground down.



Here you can see the rests.

...and a few more photos. The second switch, ceramic wire nuts, and the second rest.

Found these in the drawer of the stand that the grinder came with. Actually I spent the $10 bucks mostly because I saw these.

I snapped a few pics of some of the other old gear i have in my shop while I was at it.

I was thinking it may have been a dentist’s or dental lab polishing machine.
My father had a similar on years ago that I think had a 3 position switch to give 2 speeds.

Here is another similar looking machine I turned up in a Google image search .

http://www.practicalmachinist.com/v...nd-history/s-s-white-dental-lab-lathe-112348/

Some of the more modern ones look like they have a grinding wheel on one side perhaps for sharpening dental scraping tools .

https://www.google.ca/search?q=Dent...=Vintage+Dental+Lab+Polishing+Machine&imgrc=_

Regards,
Jim

Thanks for the lead Jim.