Re: [CAD_CAM_EDM_DRO] Changing over to VFD and 3 Phase Motor

The vector duty and inverter duty motors are meant for very low speeds,
about 10 hz down to 1-2 hz.
Basically, they will not overheat

You are very unlikely to need these very low speeds, about 10-30 rpm,
with a mill drill.
You could use a normal motor and a small computer fan to keep it cool.
They are better motors, will live longer, turn smoother - none of which
matters with a mill drill. The case bearings, duty cycle, mass etc. of
the machine is fairly light - both motors will perform the same in a
mill-drill.

So, in a nutshell, you don´t need it.

You would need a vector duty motor if;
you mount a spindle position sensor i.e. encoder.
You direct drive your spindle as a servo drive.
This would allow you to do direct, rigid tapping. Here your rpm and
rotational speeds go down to zero.

This is a very advanced (and for some, a VERY useful thing) feature, and
less than 1% of e.g. mach sw users use it.
For production, involving tapping, it would be great.

My non-inverter duty 3-phase runs really well to 15 rpm. But it is a
very good 3-phase motor (bridgeport).


Torsten wrote:

>
> Finally made up my mind to change over to 3 Phase with a VFD for my
> Mill-Drill Machine.
> I got a good deal on a GS2-22PO Drive from Automation Direct.
> I should be able to controll the Spindle Speed from the CNC-Controller
> with this Drive.
> Now I need to replace the single Phase Motor with a 3 Phase 220 volt
> Motor.
> A lot of advertisement about Vector Duty Motors and Inverter Duty.
> These Motors are considerably more expensive.
> Are they really worth the extra Cost?
> I assume that those features will give a wider usable range of Spindle
> Speeds without changing Belts.
> Is it worth the difference or just a bunch of marketing?
>
>