Friday, August 12, 2016

A Brook Electric 1 HP Motor

This old motor was on a Rockwell/Delta 10" table saw of my acquaintance. The post concerning the saw is here.

Here's a view of the opposite side, where the connection box is.

And here it is with the connection box opened up.

That's the most spacious connection box I've ever seen on a motor.

Following is a transcription of the I.D. Plate data:

  • FRAME EL143T
  • SERIAL No. 185079T
  • H.P. 1.0
  • F.L.SPEED 1700
  • V. 115/230
  • A. 14.2/7.1
  • Hz 60
  • PH 1
  • CODE K
  • MAX. AMB.°C 40
A couple of points about the above:
  • "TEFC" stands for 'Totally Enclosed Fan Cooled'.
  • Note the current rating (A.) -- 14.2 Amps at 115 V! This is a motor that ought to be run from 230 V. (It's currently wired for 115 V.) It's liable to be a circuit breaker tripper if plugged into a household 15 A circuit.
The saw this motor came from must have been on a job site once where it was raining glue. The thing is an awful mess -- just encrusted with some sort of hardened muck. To restore it to good appearance, I'd have to tear it down and go at the pieces with paint remover, probably. I may do that, but not right away. I need to check this motor out and wire it for 230 V. If all is well, I can use it again back on the saw it came from. That saw is meant to get a restoration.

So, permit me to go test this motor at both voltages. 'Be back shortly.

- - -

That all worked out fine; the motor runs at either voltage.

The Wire Ends

The motor's connection wiring is of stranded wire; the stripped ends were never tinned. I don't care for that -- I like stranded wire ends to be tinned so they don't fray and lose strands. I may as well take care of that right now. Here's a before view of the wire ends.

Yuck. I can do better than that.

- - -

And here we are with the wire ends tinned.

That's better but not great. Some of those wire ends were in dreadful condition, and didn't take tinning as well as I would have liked. I may end up splicing on short lengths of wire, and insulating the splices with shrink tubing. That will give me fresh wire ends that can be properly tinned for connecting with wire nuts. We'll see.

The Output Shaft And Pulley

They're not pretty.

The shaft is 7/8" diameter. Should I ever want to increase the saw's blade speed by installing a bigger pulley, I won't be able to just go to Canadian Tire for one. The biggest standard pulley bore that's widely available at outlets like Canadian Tire is 3/4".

The pulley is steel, 3 3/4" diameter.

Both the pulley and the shaft look awful. I should get the pulley and the key off, and clean up the works. I'd like for the pulley's axial position on the shaft to be readily adjustable when it comes time to mount the motor on the saw for a trial of the saw.

- - -

And there we are with things cleaned up somewhat -- at least the key and the pulley now move freely on the shaft as they ought to,

The pulley wasn't seized on the shaft, but I needed a two-jaw puller to coax it off. The key was a bit odd. It was jammed in its keyway and had to be forced out. It's nominally a 3/16" square key, but it was oversize. I had to lap it considerably on a sheet of aluminum oxide abrasive paper to get it to fit properly. It must have been forced into place at the factory or wherever, and the pulley forced on the shaft over it.

The Box Connector

This is a frightful little mess of a thing.

It appears to be a 3/4" fitting -- 1/2" would be quite adequate. I can't imagine what whoever installed that had in mind. I'll be replacing that with something more suitable.

- - -

Anyway, that's the story so far. This old motor appears to be in fine condition, aside from its cosmetic issues. It's now at least fit for service, once I'm ready to give the saw it belongs to a trial.

* * *

Back again. I was having so much fun with this I thought I'd return to it.

More On The Box Connector

That cable connection point at the centre top of the connection box is not 3/4" pipe as I thought. The diameter is about the same, but the thread pitch is finer -- it's 16 tpi, yet it's a tapered thread like a pipe thread. It's something I've never encountered before.

What I'll do is I'll cap off that hole up top, and make a new hole in the side of the box to accept a 1/2" box connector. Here's what I've come up with to cap off the useless hole

Basically, two 1/4" fender washers and a 1/4"-20 screw. The assembled appearance is pretty good.

The Cooling Fan

The cooling fan resides under a vaguely bell-shaped cover at one end of the motor.

And here's the cooling fan revealed.

That fan appears to be a press fit onto the end of the motor's shaft. The likelihood of my getting that fan off without damaging it is slim to nil. That pretty much obviates an attempt at a full blown restoration job on the motor.

Sandblasting The Motor's Frame

To improve the motor's appearance, not to mention its air cooling, I had the idea to take my toy sandblaster to the motor's frame, if only to see what sort of result I would get. (Since the motor is a sealed unit with the connection box's cover in place, I could sandblast without fear of harm to the motor's innards.)

The result turned out to be not too bad, though far from perfect. Here's a view of the motor after sandblasting.

It looks good enough now that I may strip and paint the connection box and the fan cover.

A New Connector For The Connection Box

In the end wall of the connection box, opposite the capacitor, I drilled a 5/8" diameter hole and filed it out to 13/16" diameter. Now I have a place for a 1/2", 90° connector, like so.

That's much better than the nonsense that was originally installed in the top of the box.

- - -

To be continued.

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