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Rebuilding a US Electrical Tool #500 Pedestal Grinder

A_Pmech

Stainless
Joined
Dec 27, 2004
Location
Central IL, USA
I started this a few weeks ago on another message board but I figured PM would like to see it too!

The grinder is a US Electrical Tool Model 500. Specs are 1HP, 3-phase, 220V / 440V, 12" x 1.5" wheels at 1,800 RPM.

I bought this grinder on another message board last month and disassembled it in the seller's driveway for transport in the front seat of my Camaro:

grinder1.jpg


All the parts boxed and jammed into the car:

grinder2.jpg


Back home at the shop, already disassembled and ready for overhaul!

grinder3.jpg


After talking with Coleen at US Electrical Tool I was able to determine that my grinder, serial# 39 43 55 was produced December 1946 as one of an order of 14, likely for the US Government. The motor was manufactured by Lima, who is long since out of business.

New tool rest castings should be available, but she strongly suggests I send one of the originals in so they can match them up to their current stock.

A comparable Model 500 sells new for roughly $5,000 depending on options.

After disassembling it to the component level I decided to rewind the motor, in part due to the condition of the winding varnish and in part due to the deterioration of the lead wire insulation. The grinder is already over 60 years old and it will be over 100 years old when I intend to be done with it. Plus, rewinding a small polyphase motor is actually rather relaxing.

grinder7.jpg


Here's the motor core before stripping:

grinder9.jpg


Here's the info I collected for the rewind:

Bearings: New Departure 77206 crosses to SKF 206 2Z
RPM: 1,800
Amps: 5.5
HP: 1
Phase: 3
Cycle: 60
Voltage: 220-440
Winding Connections: Star
Coil Span: 7 slots (Pitch 1-8)
Winding Type: Distributed
Coil Shape: Round Nose
# of Poles: 4
# of Slots: 36
# of Coils: 36
# of Coil Groups: 12
Coils / Group: 3
Turns Per Coil: 45
# in hand: 1
End Room: 1-3/8" Front 1-1/2" Back
Lead Wire Size: 16ga
Lead Wire Length: 12"
Coil Wire Size: 22ga

Pulling coils:

grinder13.jpg


Here's the core ready for the base layer of insulation after blasting with walnut shells:

grinder16.jpg


Using my rebuilt Pexto shear to cut the base insulation:

grinder18.jpg


Here's the base layer of insulation installed in the core:

grinder20.jpg


That's where I'm at so far, I need to build a wire tension device and a winding head to wind the new coil groups before I can continue.
 
Man you are like a master rebuilder, all I know is lube the bearings they about tanned my hide over it see my freewheeled for 25 min thread.
 
Man you are like a master rebuilder, all I know is lube the bearings they about tanned my hide over it see my freewheeled for 25 min thread.

LOL! I'm putting new bearings in, so hopefully I won't have that problem for a while!

Your thread is what made me decide to post this here! :D
 
Please keep the pics coming especially of the rewind, enquiring minds want to know the results!!

machinemanx2 congrats on finding your "NIPPLES" great grand kids will probably be the next to grease it :-)
 
A_Pmech -- Well, after following your Do-All bandsaw restoration (unbelievably nice and detailed to the max), I have come to the conclusion that a.) you have way too much free time, and b.) I wish I had 10% of your energy for this type of project.

BTW, nice transport setup in the Camaro with the seat missing. Can you fit a table saw in there? :-)
 








 
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