Re: [CAD_CAM_EDM_DRO] calculation of motor torque

Jon Elson wrote:

>Boris Maraž wrote:
>
>
>
>>Hello!
>>
>>Somebody have formula to calculate approximately how much torque must have stepper motor to drive the router with 10mm/turn (or 20mm/turn) lead screw and to get speed around 30cm/second and the weight of moving arch over table will be around 15kg. Is it possible to do this with steppers or I must use servo motors.
>>
>>
>>
>>
>Depending on the weight of the arch (gantry) and the type of leadscrew,
>you can make
>rough guesses. One big question is how fast you need that gantry to
>accelerate to the
>30 cm/sec velocity. The greater the acceleration, the greater torque the
>motors need
>to exert. If the gantry is over 50 Kg, or you need acceleration to speed
>in less than
>1/4 second, you are WAY into servo territory. If you can accept
>acceleration in the
>1 sec+ range, and the gantry is as light as you plan, it might be done
>with modest steppers.
>If you use ballscrews, the torque will be light. If you use an Acme
>leadscrew,
>I think you may have serious wear, not to mention the drag of such a screw
>running so fast.
>
>

Whoa! I slipped a decimal point, another post brought this to my attention.
30 cm/sec is VERY fast, no way you'll do this with steppers. I was thinking
3 cm/sec!

Jon