> > Theoretically that may be true, but you can't feel slop in the middle of > the step at all on these new stepper motors. They feel tight when they are > being held in position.. If you grab a knob on the shaft when they are > energized stationary there appears to be no slop. > > If you want to use steppers you need to make one step of the motor equal > to a machine movement of less than the desired precision of the machine.. > That dictates your motor gearing ratio to the load. Unfortunately that > also dictates the max speed of the machine since steppers run out of > usable torque at relatively low speeds compared to servos. > > But for many applications that is not a problem. > > I have an old Bridgeport mill with steppers and I think it was geared > such that one step of the motors was equal to .001 of an inch which > apparently was good enough for thousands of machines shops. > > On the other hand the mill I have is no speed demon during rapids with > the old heavy finned motors..50-60 ipm is quite reliable. which at this > point is fast enough. > > Dave > > True. Quite a large amount of machines run steppers, not only old chunks but knew ones too. Ok, they have less transport speed than I am looking for but as I see it it's a matter of putting small motors and cheap drivers in to cut the costs. I have no problem with a belt reduction in between to keep the tolerances in range of the motor movement (or to increase the movement for the motor). I can't really let the closed loop stepper setup go, it's still very cost friendly and I get brushless motors at the same time...
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