Re: [CAD_CAM_EDM_DRO] Servos vs Steppers costs

Mike Gann wrote:

> Jon -
>
> If he used a 2:1 belt reduction, does he acheive
> an increase (X2?) in linear force at the cost of
> some speed?

With steppers, yes, as the speed is pretty much fixed by inductance vs.
supply voltage. With servos, the motor speed is fixed by DC supply
voltage, but so many motors are designed for fairly high speed, and
the leadscrew RPM is so slow on most machines that the belt drive
doesn't hurt you. It is something like trying to start moving a stick shift truck
in 4th gear. It will take all day to get it moved 25 feet.

> In trying to figure out the formula you used below,
> would the circumference of the drum become the circumference
> of the pully mounted on the lead screw?

No, you need to add 2 more drums if not direct drive. The motor has some
pitch diameter for the motor sprocket, and then the belt pulls against
some diameter on the leadscrew. The torque is linear, so a 2:1
speed reduction causes a 2:1 torque increase.

So, in the example I described, he'd just double the torque input to
the leadscrew, doubling the output linear force, too.

Jon