Re: [CAD_CAM_EDM_DRO] Re: Adequate torque from VFD driven motors?

Hi Steve:
I'd drive the machine just the way she is until something actually
breaks.
You may get another million miles out of her without even a hiccup.
Cheers

Marcus

----- Original Message -----
From: "scyvt" <scy@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, May 28, 2002 5:36 PM
Subject: [CAD_CAM_EDM_DRO] Re: Adequate torque from VFD driven motors?


> Thanks to those who replied. The theory is now clearer, but the
> practice still poses questions.
>
> The lathe I am working on is a 50's vintage Rockwell 11" with what they
> call a "perfected" VS 1 1/2 hp drive. (Yes, it has functioning back
> gears.) The amalgam of sliding sheaves, bearings, shafts, cams, gears,
> etc seems awfully complex to restore and maintain compared to an
> electronic VS drive, provided that performance would be equivalent or
> better.
>
> A VFD controlling a 3 ph motor came first to mind, since I have on hand
> many 3 ph motors to choose from and the VFD could be run from a 1 ph
> supply with suitable derating. The suggestion that a larger than
> original motor may be required gives me some concern - doesn't that
> create a possibility of greater-than-design torque at higher speeds
> that could cause harm to the machine, or even operator if a
> catastrophic failure occured?
>
> Perhaps a dc motor and controller would be also worth considering,
> especially if that would address my concerns about low-end torque while
> keeping the 1 1/2 hp factory spec.
>
> So, how do ac & dc spindle drives compare in terms of cost,
> performance, availability, and ease of CSS implementation. And how do
> the several dc control approaches compare?
>
> TIA
>
> Steve Clay-Young