Re: Steppers

--- In CAD_CAM_EDM_DRO@y..., Gene <capper@i...> wrote:

> If I use two identical stepper motors hooked to two gecko 201a's

and run

> by the same step & dir. signal , could I expect good results? is

there a

> possibility of one motor missing steps when the other doesn't? If

so how

> could I prevent this?

Steppers "miss" steps for several reasons. Sometimes rapid
acceleration or deaccelerations will cause some steps to be missed.
Running at higher speeds can be problematic. Theoretically running
two identical motors from two seperate Gecko's should give you
identical results. Determine the maximum rates to run a single motor
and back off that 20% for a safety factor. If you stay inside that
envelope the chances for success are much higher.

One of the areas that gets overlooked is the enemic drive from the
parallel port of most PC's I highly recommend a buffer card for
single driver card installations. It helps problems with noise and
longer cable runs and cleans up the pulses to the motor controllers.
In a design where one Step and Direction is driving two motor
controllers, a buffer card is mandatory.

A way to "square" the dual drive axis is needed so that when you home
the axis it will drive both sides to a know position. As one member
suggested you can just put in hard stops and drive both motors until
they stall. A more elegant system is to provide a logic gate that
controls the Step signal to each motor controller so that the first
one that hits a home sensor stops receiving step signal while the
other continues to run. Once both recieve a signal the Controller
Software gets the signal that home has been reached.