Re: [CAD_CAM_EDM_DRO] Re: Stepper Motor or Servo Motor Requirements for my Van Norman #12 mill?

Thanks for the clarification....what are typical desirable max feed speeds
for a big mill like mine? I don't know what feeds are practical...


R. William Kichman, P.E.
Kichman Engineering Associates
103 Old Furnace Road
Cornwall, PA 17016-0643
tel/fax 717/270-0714

----- Original Message -----
From: "Mariss Freimanis" <mariss92705@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Friday, May 02, 2003 9:52 PM
Subject: [CAD_CAM_EDM_DRO] Re: Stepper Motor or Servo Motor Requirements for
my Van Norman #12 mill?


> Bill,
>
> It may not be quite that simple. Unlike steppers, servo motors
> generate their rated power at about 80% of their no-load RPM.
>
> Figure out what is the fastest speed (IPM) you need the Z-axis to
> move at. Knowing your leadscrew pitch (10 TPI?) calculate how many
> RPM it has to turn at that speed.
>
> Divide that into 80% of your motor's no-load RPM.
>
> The answer will be your gear reduction ratio and the motor will need
> reduction gearing.
>
> You won't find a 1,200 in-oz continuous rated torque motor. If it's a
> big one it may be 1,200 in-oz when stalled but its continuous torque
> will be about 200 in-oz in that case. Run it at the bigger number and
> you will burn it up.
>
> Let's say it is 200 in-oz at 1,500 RPM (1,800 RPM no-load). That's
> 3/10 of a HP. Let's also say you want 60 IPM on the z-axis. At 10 TPI
> the screw would turn at 600 RPM while the motor is turning 1,500 RPM.
> The ratio is 2.5:1, being your reduction ratio.
>
> The motor, reduction gearing and screw would generate 1962 lbs
> of "lift". Figure on 1/2 that when you take the screw efficiency into
> account.
>
> Mariss
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Bill Kichman
> <billkichman@c...> wrote:
> >
> > At any rate, if I install a big 1200 oz-in servo, even a 1/4 to
> 1/2hp servo
> > on the knee, and smaller servose or even steppers on the x,y, and
> possibly
> > later, A axis(rotary table) shouldn't I be "in business" with this
> setup?
> > Additional thoughts are welcome.
> >
> > Bill Kichman
> > R. William Kichman, P.E.
> > Kichman Engineering Associates
> > 103 Old Furnace Road
> > Cornwall, PA 17016-0643
> > tel/fax 717/270-0714
>
>
>
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