Pro's:
1. More precise control of stepper motors. The encoder in the motor, if
optical so its instant, controls the motor much more precisely. If in
stopping the motor, rotor inertia causes even a 1 count overshoot, the
controller instantly reverses the motor to correct its position.
Con's:
This means the 42C series of these motors are not usable because the
internal time lag of converting their hall effect encoder into something
usable in an AB + index, in feedback circles is a Nyequist error, they
cannot be used in a moving position mode since they move in jerks.
Stationary they are very accurate, moving they are a disaster.
Pro:
2. The magnitude of the error controls the motor current. So they use
only as much current as it takes to move the machine to the position the
stepper driver, connected directly to the motion output, requests, a
savings that can be seen in the monthly power bill, and motors run a lot
cooler.
Pro:
3. unlike std steppers, these controllers have an output that in the
event they meet an immovable object and lose home, linuxcnc can be
stopped so fast the part is not damaged Move the tool that caused the
stop out of the way, rehome that axis (or the whole machine if toggling
F2 as e-stop was used for the stopper) and run from where it got stopped.
I wish I could post pictures, but John has never allowed me to post one
yet in 20+ years. The same gcode sent to two printers, one with input
shaping tuned and enabled, one retrofitted with stepper/servos for xy.
Text is engraved indicating the tooth shape version, and size of the
maple screw, on the unused sides of the half nut. I can print and read
it because I know what it says, but you can clearly read it made on the
printer with the stepper/servos and no input shaping, running at twice
the speed of the high priced printer and nearly 10x the speed that
printer had OOTB 3 years ago.
Cheers, Gene Heskett, CET.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
