Alternative Motors for the Emco Unimat 3

Unimat 3 Lathe

The Emco Unimat 3 is one of the best small lathes I have ever used. However, it has one serious flaw and that is the motor that is slightly underpowered, gets very hot and hence limited running time of ~8 minutes.

I have in the past managed to clean and replace the brushes on the motor for my lathe.

As you can see, over time a lot of dust is generated. A good brush out with a soft paintbrush and a vacuum clean works wonders.

However, these motors are going to fail at some point and so I wanted to find alternatives. One alternative is the Unimat 4 that has a variable speed control drive. Other options:

Sherline DC Motor

Gerry from Toronto dropped me a line about the modification he had made to his Unimat 3.

The Sherline DC motor has stats that are quite close to those of the original motor:

  • Duty rating
    Continuous–10 oz. in. at 6100 rpm,
  • 0.85 amperes;
  • Intermittent–30 oz. in. at 5500 rpm, 1.75 amperes (5 minutes on / 15 minutes off)
  • Output horsepower
    .06 KW (60 W) at 10 oz. in. / 6100 rpm

The motor is available from Sherline.

Sewing Machine Motor

I’ve used a sewing machine motor on the drill/mill attachment for years.

The plate is a piece of 2mm steel with the edges bent up each side to give it some rigidity.

The pulley on the motor was turned up out of brass and then some simple brass pillars to space the motor away from the plate.

This is quite low power of around 60W, but runs and runs. This is quite an old motor with a metal case and I think this helps with the heat dissipation and with the overall ability to mount it onto a plate.

120W Sewing Machine Motor

I finally bit the bullet and bought a 120W sewing machine motor on ebay. If you search around you can get motors that run clockwise and anti-clockwise – depends how you want to mount the motor relative to the main shaft.

I removed the plug connection point and fitted a small switch.

The bearings on the motor are just phosphor bronze and with a plastic case you will have to be careful with respect to side loads.

 

 

 

About Nigel 173 Articles
Have been making models since I was around 7 years old and using a lathe from the age of 11, a self taught engineer with a passion for making model engines.

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