Re: [CAD_CAM_EDM_DRO] Re: VFD for a 15HP CNC lathe

Hi Fud;

Most likely the motor you describe is a fan cooled DC servo motor. It
is to uncommon at all for servos, be they AC or DC, to have a seperate
cooling fan. Some manyfactures have also been known to resort to
water cooling or other techniques.

The reason for the supplemental cooling is really straight forward, if
the servo is does not obtain and hold suffiecent speed any built in fan
it may have can not do its job. In the case of a servo it is poosible
for that motor to be working very hard and never obtain a spped to raise
a breeze out of its fan. Thus many manufactures resort to motor
driven fans. This is not unlike the automobile industry where many of
the new cars on the market have electrically driven radiator fans.
One reason, amongst many, is to make sure that a proper air flow is
always passing the radiator.

I woud seriously look into just how much horse pwoer you really need on
this lathe. That and the usable range of continously variable speeds
required. If you have a very specific application for the lather
with a small required spindle RPM range you may find that it is possible
to use a smaller motor with a bit of careful gearing selection. A big
motor can make up for limited gearing but at the expense of effiency.
In this day and age one should not underestimate the importance of
effiecncy.

Thanks
Dave





fuddham@... wrote:

>Jon,
> The original motor has a cooling fan and motor sitting on top of it. I think this machine has a clutch so that the motor starts unloaded and continues to run even when the spindle is stopped.
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>thanks,
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