Re: [CAD_CAM_EDM_DRO] Re: Servo hardware

On Wed, 29 Dec 2010 05:19:58 -0000, you wrote:

>What I like about closed loop to the computer is I can hit feed hold at any time and the machine stops immediately. Then to restart just hit the green run button and off it goes with absolutely no loss of position.

Feed hold only stops the axis in a controlled manner, it decelerates to
a stop. I can do that on a stepper machine, without closed loop and with
absolutely no loss of position.

What I can't do is ESTOP the machine, that will loose position. The
steppers jump to the next nearest full step, which may not be quite
where you want them.

I know the above to be true of Mach.

Depending on your servo machine, how it's wired and configured, similar
may apply. After an estop both are likely to need re homing and setup
checked.

Not 100% sure on EMC - documentation is sparse on Feed hold.
Unlike Mach, you can't jog in Feed hold or do anything else, so it's
pretty worthless.

You have to stop, note the program line, do whatever you have to like
clear swarf, replace insert re-home or whatever then restart, a PITA.

Steve Blackmore
--