Re: [CAD_CAM_EDM_DRO] stepper - servo Holding tourque

Marv
I am working on a bench top Mill/drill. Off shore brand weighing approx 850
lbs and was considering the effect of the loss of the pulley "gear
reduction" effect on the system.
I wonder if my change from a .100 lead screw to a .200 ball screw will
negate the loss of torque [by the loss of the pulleys on the x axis] on the
system.
Owen

> Owen,
> I've been following your scenario with interest, and I may have
> missed the type of mill you're converting. I'm wrestling with the same

kind

> of decision.
>
> Marv Frankel
> Los Angeles
>
>
> > Jon,
> > my decision to go direct drive was more out of convenience. Since I had

to

> > make new bearing blocks for my ball screw conversion, I decided to build
> it
> > so the Nema 34 motor could mount right on the end with a keyed female
> > coupler. I was intending on using minimum 400 in/oz steppers, though I

am

> > likely going to purchase the Motion Group
> > [http://www.motiongroup.com/cncpkg.htm%5d package with 750 on/in motors.

My

> > ball screw is a .200 pitch.
> > Thanks for the informative link. I'll be sure to read it through several
> > times.
> > Owen
> >
> > > Well, with a direct drive, you get much higher speeds, and less

torque.

> > > With a 2:1 toothed belt
> > > reduction, you double the torque but half the speed. Servo motors
> > > usually have lots of speed,
> > > so a belt reduction is a good move. Steppers are usually lacking on
> > > high speed, so direct
> > > drive may be a much better choice.
> > >
> > > If you give me specifics, (motor specs, lead screw TPI) I can crank

some

> > > numbers for you.
> > > Or, see my page on this at

http://www.timgoldstein.com/CAD_CAM/motor.htm

> > >
> > > Jon