Re: VFD for a 15HP CNC lathe

--- In CAD_CAM_EDM_DRO@yahoogroups.com, fuddham@a... wrote:

> Tom,
> I need speed control for the motor. The original motor was DC

and I

> have the electronics, but they are in a seperate cabnet that all

the wiring has

> been unhooked from. I was planning on getting an AC motor to run

the lathe. I

> currently have several VFD's running equipment in the shop from

single phase,

> but the largest is a 2hp CNC Bridgeport Series 1. I also have a 20

hp Rotary

> phase converter running a 10 hp CNC lathe (YAM Chucker CK-1).
>
> Thanks,
>
> Scott Hamilton

Actually controlling a big DC motor is easier than a big AC one.
There are a lot of larger DC motor controls and most will take a 0 -
10 VDC voltage input for remote speed. If it were mine I would try
to use the DC motor but build/buy my own speed control. What is the
DC motor specs? If it is one of the 180DC ones than the control will
be pretty cheap. You don't need a cabinet full of components to get
there. If you are going to retro fit the CNC controls you may not
need 3 phase at all.

The VFD's take the AC input, rectify it into DC, then PWM it to
simulate an AC waveform of varying frequency to change the speed of
the motor.

15HP DC motors are harder to find and in my option more valuable than
15HP AC 3 phase motors.