Retrofitting an Old Milling Machine with a Modern Brushless DC Motor

Most big machine tools, like lathes and knee mills, use huge three-phase motors, often running at 480V. Those are extremely powerful, but they’re also very heavy and difficult to power if you aren’t in an industrial space. So when his old milling machine’s motor bit the dust, We Can Do That Better replaced it with a modern brushless DC motor.

This isn’t as crazy as it sounds at first, because lots of smaller machines, like mini lathes and mini mills, use brushless DC motors these days. They’re powerful for their size, relatively affordable, and can work with full speed and/or torque control.

On top of that, the mill in question, an old Wabeco machine, isn’t exactly a behemoth. It originally had a conventional universal motor, which is the cheapest option that would have been available when it was new.

With that in mind, We Can Do That Better snagged a beefy brushless DC motor with a complementary speed controller. That controller has a simple interface for adjusting direction and speed, though all of the labels are in Chinese.

Mounting that proved to be quite the challenge — we’re not talking about a drop-in replacement. We Can Do That Better ha d to use the limited tools he had on hand to modify the Wabeco machine and fabricate mounting hardware. While he was at it, he dramatically improved the Wabeco head and spindle assembly, which were poorly manufactured. They had many burrs and rough surfaces, which We Can Do That Better cleaned up.

But the result was worth all of the effort, as the new motor works much better than the original. And all of that cleanup has the machine running much more smoothly.

This may not be suitable for “real” mills with 5+hp motors, but it is certainly a good option for an older mini mill in need of an upgrade.