Re: Bridgeport Boss 6 Stepper Motors

Jon, I have no problems making the calculations for torque and power
required based on ball screw efficiency, TPI, IPM rapids, etc. Where
I fall short is in the machinist knowledge area. I don't have a good
feel for how much force is required on the X, Y, and Z axis for a
series 1 machine.

I was looking at some 400W, 3000RPM servos that would provide about
600lbs of force with 300 IPM rapids on a continuous basis with a 2:1
reduction. These are roughly 1/2hp motors. Based on your success with
1/8hp motors I guess these are more than enough. Thanks for the info.

Best Regards,

~petev

--- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
> vavaroutsos wrote:
>
> > Does anyone know what the model number of the stepper motor that
was
> > used on the Series I Bridgeport with Boss 6 control? The ones
from my
> > machine are already gone. I know they were made by Superior
Electric,
> > but nobody at Bridgeport or Superior knows what was used.
> >
> > I would like to find the specs so I can get a better idea of the
> > force that Bridgeport provided on each axis. This will help me in
> > sizing some new servo motors.
>
> Note that servo and stepper motors have such different performance,
that
> a direct comparison is not correct. Steppers have a severe falloff
in
> torque as the speed increases. Servos generally provide full torque
> up to the maximum speed that can be achieved with a perticular power
> supply voltage. Servos also have the capability to provide peak
torque
> that is above the continuous rated torque for some short time.
>
> So, if 1600 In-Oz motors stepper were used, a 400 in-Oz continuous
> rated servo motor would likely do. Also, if the steppers were
direct drive,
> you could use a 100 Oz (cont) servo with a 4:1 belt reduction
ratio, as
> the servo generally has no trouble spinning at several thousand RPM.
>
> What you might want to do is define the highest feedrate and rapid
traverse
> speeds you will want to run at, and the leadscrew pitch, and do some
> elementary calculations to determine the motor needed to reach that
> performance. (I'm using 1/8 Hp (cont) servo motors on my
Bridgeport,
> and I can deliver 1000 Lbs linear force to the table, which seems
to be
> enough to bust things pretty good!) See
http://206.19.206.56/motor.htm
> for how I calculated this.
>
> Jon