Re: [CAD_CAM_EDM_DRO] Re: formula ?

dave_ace_me wrote:

> Hi Jon,
>
> great explanation. I couldn't get the concept that the lead of the
> screw was part of the circumference part of the equation.
>
> OF course that makes sense, a 1/2-5TPI 1/2 screw or a 2"-5tpi will
> still move the table one inch for 5 revolutions. so the actual
> diameter or circumference of the screw is not important.
>
> I noticed that we rate steppers in oz/in but power in inch/lb.
> Can I assume that 16oz/inch is the same as 1in/lb?

I believe this is correct. There are so many torque measurement units, its
a mess. N-M, N-cm, gm-cm, oz-in, lb-ft, .........

> That would make a 50oz/in stepper 3.125 inch/lb. Fits close to your
> 10 inch /lb value. Yours seems to be 150oz/in.
>
> so my 50in/oz at 2:1 is 6.25 in/lb on the leadscrew. The 13tpi
> (0.0769"circumference/0.02448dia/0.012243radius) then 6.25 / 0.012243
> = output force
>
> 6.25 / 0.012243 = 510 pounds of force. That kind of force will bend
> the noodle of a leadscrew I am using.

Yup, sounds good. but, remember, stepper ratings are good at zero speed,
only. They drop off very rapidly as speed increases.

Jon