Re: [CAD_CAM_EDM_DRO] formula ?

batwings@... wrote:

> I don't think this is correct.
>
> At 06:14 AM 4/15/02 +0000, you wrote:
> >docholliday01201 wrote:
> >
> >> once again, who knows the formula for converting rotational torque at
> >> the motor-to linear force at the table ??
> >
> >Its really simple. Consider the leadscrew to be a drum pulling a string,
> >where the circumference of the drum is equal to the lead of the screw.
> >If you have a 5 TPI screw, that is the equivalent of a drum with
> circumference
> >of .200 in, or .0637" diameter or .0318" radius. If the motor produces 10
> In-Lb,
> >that is the same as 10 Lbs pull at a radius of one inch. This will translate
> >to 10 / .0318 = 314.16 Lbs linear force on the table! Pretty amazing, these
> >ball screws!

How can it not be correct? Two eqivalent mechanisms (neglecting friction)
should produce the same results. A drum pulling string or a screw moving
a linear slide by the same distance per revolution, have to be equivalent.
(This is only true for ballscrews, because other screws have significant
friction which increases under load.)

Unless someone can point out where I went wrong, I stand by this
calculation.

Jon