Re: Switches Anyone?

["Bob La Londe" <none@xxxxxxxxxx>]

"Jim" <alarminex@xxxxxxx> wrote in message
news:fdabc4ff-d2e3-463a-b60e-a3f76bce7df2@xxxxxxxxxxxxxxxxxxx
> On Tuesday, April 16, 2013 4:02:18 PM UTC-4, Bob La Londe wrote:
> Hey Joe! > > I was looking for something else and came across these. > >
> http://www.aliexpress.com/wholesale/wholesale-push-button-switch-box.html
>
> Aliexpress is a sale listing / escrow service for China based companies.
> Often I have found items on Aliexpress for the same price as on Ebay, but
> the item on Aliexpress always seems to be more "complete." I bought a
> variable frequency drive through Aliexpress for one of my spindle motors a
> while back. It was the only place I could find one that met all my specs.
>
> What is a variable frequency drive?  I know what is sounds like it is but
>
> Are you just talking about variable 50/60 cycle or something different?
> And why would you need that on a spindle drive ( I presume for your CNC
> machine)

Well, that one will be set to run up as high as 665 hz to drive the spindle
motor upto about 40,000 RPM at the high end.  My big mill has one that is
set for 3 hz to 120 hz to drive the spindle from 96 RPM to about 3600 RPM.

You can vary the speed of a three phase motor by varying the frequency.

Upto 24000 RPM motors that run at upto 400 hz AC are fairly common.