Originally Posted by
joeavaerage
Hi,
it very tempting to believe that increasing the number of microsteps also increases the resolution, but the practical reality is that it does not. The effective best
resolution for a two phase stepper occurs at half-stepping, ie 400 pulses per revolution.
The real reason we use microstepping is smoothness of motion. The idea was first invented by astronomers who wanted much smoother motion from the steppers they use on their
telescopes. The higher the microstepping the smoother the motion, however the higher the microstepping requires ever faster signalling to the driver to cause the stepper to spin at
maximum speed, and you may find the parallel port is just too slow.
For instance lets assume you want the stepper to spin at 600rpm (10 revs/sec) to make the machine go as fast as you want:
4 microsteps per fullstep =800 pulses /rev and at 10 revs/sec requires a pulse rate of 8000 pulses/sec.
32 microsteps per fullstep=6400 pulse/rev and at 10 revs/sec requires a pulse rate of 64000 pulse/sec
So you can see that a parallel port would have almost no chance of driving the stepper to full speed at 32 micro step per full step but have no trouble
driving it to full speed at 4 microsteps per full step.
For this reason most people use 4, 5, 8 or 10 microsteps pert full step, corresponding to 800, 1000, 1600, 2000 pulses per rev. It s good balance to get smooth motion
without requiring blindly fast pulses from your controller.
craig