On 6/13/23 01:41, andrew beck wrote:
Just to confirm also
Gene.
My vfd only holds the motor at full torque to resist loads briefly.
So it never actually causes problems
I think the rating is 1min at the 150 percent rated torque.
So it's only to respond to forces and make a good fast pid loop
Not to run that way all the time
It appears fanuc thought of that better than linuxcnc does, altho it may
be possible where the vfd is controlled by something like the serial
interface I'm using on the 6040 mill, which speaks rs485 to control its
water cooled spindle. But thats a 24k rpm spindle which I don't run
below 2k and it doesn't have much torque at 2k and it warms the water up
pretty fast below 8k. In this case however, the pid is in the vfd, and
appears to be quite tightly controlled. Apparently the vfd autotunes.
That one Just Works so I haven't investigated further. No pids involved
anyplace else except the one in the 3 phase stepper/servo on axis B.
Ditto my sheldon lathe, which now has 3 phase stepper/servo's, with the
loss of home signal stopping linuxcnc in its tracks by e-stop linkage in
the hal file, in about a millisecond. Works when tested, has yet to trip
in use.
I do use a pid on the other mill, a g0704 which has a 1hp rated brushed
dc motor controlled by one of Jon's pwm-servo drivers, that control is
very tight, no audible rev change right up to stall but I hear the iron
in the motor squeaking as the servo amps current limit, set at 2x the
motor nameplate FLA, kicks in. Been running that way for around 8 years
now, still on the original brushes. Because Jon's amp is full 4 quadrant
control, the rigid tap turnaround voltage hits about 170 volts for a few
milliseconds, 125 normally on a 90 volt motor. All this isn't much use
to you though, just stating what can be done with linuxcnc.
Thanks for the clarification Andrew. Take care & stay well.
[...]
Cheers, Gene Heskett.
--
"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
Genes Web page <http://geneslinuxbox.net:6309/>
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
