Re: [CAD_CAM_EDM_DRO] Re: Added a VFD to my CNC mill

John,
Thanks as that makes more sense than anything I have heard!

As stated previously, I have limited my upper rpm, but this is mainly due
to the heating that occurs on the lower end of the quill. This has been
reported by many and seems to be related to the shaft seal more than
anything else. (Poor design)??????

Anyhow, I rarely need any speeds above 2000 rpm.



At 08:29 PM 10/30/02 +0000, you wrote:

>--- In CAD_CAM_EDM_DRO@y..., Country Bubba <axtein@d...> wrote:
> > Dan,
> >
> > I also have another file from a motor manufacturer that
> > includes this information:
> >
> > "Maximum Safe Mechanical
> > Speed Limits
> > (does not imply constant
> > horsepower capability)
> > Motor @ 1800 rpm
> > Frame Direct Belted*
> > 56-184 5400 2250
> > 213-256 4200 2250
> > 284-286 3600 2250
> > 324-326 3600 2250
> > 364-365 2700 2250
> > 404-449 2700 2250
> > *Belted per NEMA MG1-14.41 (dated
> > 1993)"
> >
> > nobody that I have talked with can tell me WHY the
> > belted rate is lower than the direct drive rate???
> >
>
>I can't be sure, but I expect that the side load on the
>shaft and bearings in belted duty is the reason for the
>lower speed limit. I am most familiar with larger motors
>(5HP and up, to 600-1000 HP). In the larger sizes, there
>are different motor designs for belted vs. direct drive.
>Bearings and shaft sizes, among other things, are adjusted
>to handle the side loading.
>
>John Kasunich

Bubba

OLDER THAN DIRT
Country Bubba
(Actually the inventor of Country and Bubba)

axtein@...
LaGrange, GA

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