Re: Treadmill motor


One of the reasons for your success is the size of your motor.  I guess the original motor on the lathe was less than 1HP , so your motor is over 2x the size of the original.  That gives you a lot more torque at low speeds.



On 02/18/2019 04:18 PM, Nitro wrote:

On my 11"  Logan 922, I went with a 2 horse 1750 RPM 3 phase motor with a VFD.
Drive manufacturers recommend using an inverter duty motor because they have more substantial insulation which can ultimately get burned off a standard 3 phase motor in slow speed situation.
A better choice for a phase converter would be a rotary one of it is in your budget, but less money usually speaks louder when it's not in a full production setting.
In a hobby machining setting, I chose the bigger motor in order to gain more horsepower under the heavier loads that tungsten carbide tooling while maintaining proper surface speeds in larder diameter work.

I can slow it down to about 2 Hz, but only for short runs dues to the loss of proper speed for the motor to cool itself. I limited the VFD to only allow an 85 Hz input to prevent overspeeding the motor and bringing about a catastrophic loss of the windings. Under normal operation, I rarely run below 30 Hz and utilize the OEM gearing on the lathe to arrive at my intended speeds.
I also mounted an inexpensive hall-effect digital tachometer near the left hand side of the spindle with the magnet epoxied to the cone pulley end thrust collar.

In all, the added power is always there if you need it, and the tach lets me more accurately arrive at the surface speed I desire during operations.

I considered running a DC motor on a South Bend 10K I am in the process of reworking, but decided against it with a plan to duplicate what I did on my Logan.

I'm hoping that 50 years on a job shop floor might qualify me to state my opinion here   ; )

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