About: Last time in my life that I saw the moon that close to me... I was born in the capital city of a country that no longer exists.... I'm in my own timeline and an Electronic Engineer... Received my first degr...

A large cast iron ( 12" jaw )  wood planer powered by a Repulsion-Start  Induction-Run motor.

This is a class of motor that overcomes the induction motor's low starting torque
and incorporates the large starting torque,
while loosing the noise and brush wear of a repulsion motor.

For those who are not interested in the speed torque can skip the next step.

Curious about IRON PENNIES well you are in luck.

Step 1: THE NEED... THE NEED............. FOR TORQUE and Speed

The starting of a large Planer takes more toque then an induction machine can provide
in accelerating the mass of the single edge blade in a massive flywheel.

The first graph ( Third Pic ) plots the speed torque of a repulsion motor
which has a strong starting torque at low speed.

See the ( First  Pic ) a simplified repulsion motor wiring diagram.
After 40 seconds the repulsion motor reaches speed and the brushes lift off the
commutator turning the motor into an induction machine for planing. 
Here is a pointer to an actual repulsion motor starting a planer wind-up
that you can see and hear.

See the ( Fourth Pic ) a simplified Induction motor wiring diagram.

The second graph ( Sixth Pic ) plots the speed torque of a Induction motor
which has almost no starting torque at all  ( used for fans )..


IF you skipped here from the Introduction you may want to use this pointer to see and hear
an actual repulsion motor wind-up sound starting this planer.

A safety cover blocks access to the very dangerous spinning steel cutting flywheel blade.


As you can see the repulsion motor uses stationary brushes on the rotor
with attached commutator to achieve the starting torque.
This configuration is much like a shunt motor.


Here are some pictures of the plane taking a cut  on a solid 4×4 segment.
This is a pointer to a planning operation you can watch and hear.

Note how the safety guard keeps the errant fingers away from the blade.

I have trimmed a solid core door in three passes to fit an older door jamb
on this machine.



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    I thought 1943 pennies were made out of steel? One of my air compressors originally came with one of these antique motors. I replaced it with a capacitor start motor. OK OK the cap start motor is 10 times the horsepower too. I still have that old behemoth motor kicking around. Maybe I'll use it on my homemade lathe someday if I ever get back into that project. Though the motor I have on it now seems to do the job fine to me.

    9 replies

    Yea this kind of Ferrous penny being in reality a Steel penny with a zinc flash because of a War shortage.
    In term of motors the older ones were more efficient and built to last.


    We basically threw everything at the enemy except for the kitchen sink. The lead pipes, the copper ones, you name it, we used it on them. My old air compressor is a war release piece of equipment. Has a 1943 date stamped into the ASME tank plate. I bleed it religiously. It probably came off a war ship. I'm not sure if the motor was original to it or not. Might be.

    That old motor I have is just too big. It is huge and is only a half a horsepower. I got a great deal on a 5 HP Weg motor, and have that on it now. All the induction motors I have today will last me the rest of my life. But I might use that repulsion one when I modify my homemade lathe some more. Right now I'm using a little half horsepower squirrel cage motor on it.

    I'd have to totally redo how my motor is mounted to use that big beast.


    Nice shop pic of a clean new motor,
    is the motor weight the belt way tension ?

    Isee a heavy solder iron hanging from a tray.

    What is most curios is the armature rotor in
    your lathe could it be for mass to smooth your work,
    or a shaft extension ?


    Soldering irons are one of those things I have a hard time not dragging home. I don't know why that one is hanging there. Probably because when I get them their cords are often tightly memory coiled and I don't like my irons like that so I relax them by hanging them for a bit. That one's cord looks nicely stretched now to me.

    What looks like a motor armature is actually a Jacobs No. 36B 3/4" chuck. Mounting it was by far the single most difficult task of making the entire machine. In the first image you can see my previous two failed attempts at getting the threads axial to the spindle shaft. I know now it isn't one of those things that just happens.

    If a picture is worth a 1,000 words it'd still take a lot of pictures to tell part of my lathe's story. So here is another. In it you can see a wooden column that partially supports the motor's weight. The column is movable so I can adjust it for the right amount of weight to maintain belt tension.

    Works pretty good, though I must admit it wasn't in my original design. The lathe was sort of grown organically from my junk collection.


    Thanks for the pic of your superb mechanism,
    "organically grown" is just prolonged fun.
    I never expected a Jacobs No. 36B 3/4" chuck makes sense though.

    Big irons are safer to cool hanging then flimsy tip over supports,
    one has got to use a wide half  pulley arrangement to keep the old cord
    from sharp edge short cracking.

    My motto is give me a big enough pile of junk and I'll build you the Death Star! For me the thrill is finding just the right piece of scrap in my collection to make something out of. This was the find today, I needed a piece of aluminum to make a stepper motor mount out of. Other holes were already in it. I consider them lightening holes now. Eventually it will mount on top of that white melamine box behind it. I just drilled holes in it, I didn't even saw it down any.


    That's a fair sized stepper and an Al piece with pre rounded edges.
    As Robin would say "Holly Stepper" pfred :-D

    You may note on national News tomorrow, we had a raging wind
    blown  blaze the "Washoe Road Fire" in the valley between Reno
    and Carson City (4500') while it is snowing ten miles west at
    Lake Tahoe (above 6500') ASL...


    A buddy of mine gave it to me, he was cleaning out a stock room at his old job, and they were going to toss it out along with some other junk. He knows how much I like junk so he gave it to me. He gave me some big NEMA 34 motors too. That one is only a twin stack 23. It is 300 oz/in.

    It is a star in a video I made:

    More about that whole deal here:

    I live in the woods and worry about forest fires. So far so good though.

    Cool well made video, I thought the fingers were familiar. 

    I have pretty much the same motor on a 100 year old belt driven lathe. It is 1 hp. Must be one of the largest and most massive 1 hp motors still running. I had a chance to buy another cheap on ebay but did not because of the shipping.

    I love this motor and its lathe, even use it on occasion.

    1 reply

    Those older machine were made to Run Cool and Work forever.
    As opposed to today's motors designed to run HOT and wasteful
    because that saves on copper and iron in lowering the price.