[modeleng] Re: Vari-speed motors
- From: "Charles & Dorothy Brumbelow" <cbrumbelow@xxxxxxxxxxx>
- To: <modeleng@xxxxxxxxxxxxx>
- Date: Sat, 10 Sep 2005 06:41:31 -0500
I don't know what you mean by "ordinary AC motor" Hubert -- split phase or a
variant thereof I suspect. If that is what you are talking about, those
motors all operate at some fixed fraction of being syncronous with the AC
line (mains) voltage. A two pole in North America is usually in the 3500
RPM range -- 60 cycles per second less slippage, a four pole is 1750, for
example. (Yes, I know Hertz is the new word for cycles; it just doesn't seem
right.) So any electronics to vary the speed of such a motor must do it by
varying the effective frequency fed to the motor, and must control the
current to maintain torque and minimize heating. Permanent magnet motor
with converter controller might be the better choice for a small motor.
Probably much easier to find and less costly, at any rate. Charles
> Hi all!
> Sorry to rabbit on and on about my construction of this little lathe.
>
> Now that various kind and clever friends have given me a variety of ideas
> regarding the boring of the headstock of this little lathe, I am able to
> proceed with detailed design. I notice that a variety of small lathes
> and milling machines are now offered with vari-speed motors. If I could
> use one of these, it would simplify the headstock design, as I could then
> have just one pulley instead of a cone of pulleys. This single pulley
> could perhaps be designed for use with a tooth belt.
>
> I am totally ignorant in the world of these vari-speed fractional hp
> motors (mine would be quite small - say 1/10 hp). In the old days, you
> had to use a DC motor, or a three-phase motor to be able to vary the
> speed. But I believe that in the brave new world of electronics, an
> ordinary AC motor can be adapted to vari-speed without losing torque at
> the lower speeds.
>
> Any ideas? Thank you in advance!
>
> Cheers! Hubert
MODEL ENGINEERING DISCUSSION LIST.
To UNSUBSCRIBE from this list, send a blank email to,
modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.
Other related posts:
