Re: [CAD_CAM_EDM_DRO] what size motor do i need

dscott488 wrote:

>I am a newbe. I have done some reading and have a router/plasma table
>almost done it will be driven by 424 oz in 34's geckos and deskcnc
>controller board. I have two question the, the first is about power
>supplys I have the amps needed but too much volts 70 I only need 40
>can i put a zener on the thing to reduce the voltage?
>

That would be one huge and expensive Zener diode! Is this a stepper or
servo system? (Gecko makes both.) I think you should be able to try
it out at 70 V. If steppers, and they get too hot, then you may, indeed,
need to turn the voltage down. Servos, for the most part, will not
mind the extra voltage. You may have to set the current limit to a safe
value for your particular motors.

> the second has
>to do with the motor torque requirement. I questimated at the needed
>torque, but the more i read the more im convinced that I may need to
>bite the bullet and buy the (right motor) for the table. the table
>moves and is heavy. I have an accurite fish scale and it says that
>the it take 9lbs to get it moving and 8 once its going. that is with
>the motors connected to the tabel through a belt. I have know way of
>knowing the additional torque required to cut brass of aluminum. can
>any you calculate or give me your best guess for the motor torque
>required.I have looked over the setup page in desk cnc and have no
>idea about motor speeds or step proccessing any help on that would
>also be greatly apriciated.
>
>

What are you using for a spindle? I designed my Bridgeport retrofit
to deliver 1000 Lbs of static thrust to the table. That is probably a bit
much, even for a Bridgeport mill, but was based on some rough calculations
of the maximum linear thrust when cutting on the side of a big end mill
and using full spindle motor HP at very low speeds, in back gear drive.

I'm sure your machine will develop much less force, especially if you are
using a router as the spindle. Let us know what sort of metal cutting you
plan to do, and what the spindle is, and we may be of more help.

Jon