On 1/12/25 12:30, John Dammeyer wrote:
-----Original Message-----
From: gene heskett [mailto:ghesk...@shentel.net]
Another way (the rattle is often because the encoder feedback is too
coarse) is to improve the encoder definition. I had a shop made optical
with 64 slots per rev, and my spindle sounded like every ball in the
bearings was square, a very worrisome racket. So I made an extension on
the rear of the motor shaft to drive an Omron 1000 ppr encoder mounted
on the rear of the motor.� But left the index on the spindle. The Omron
had a balanced output which I turned to TTL by a couple $2.00 rs485
translators.� That was too fast for the parport cards opto's, so I moved
that to the 5i25's encoder which has no glacial opto's. Then I put a
couple switches on the go704's gearshift knob to tell LCNC which gear it
was in. I now get 3000 revs in high, or 1500 in low with a switch in hal
to change the scale, which is a bit over 7000 in high gear, and a bit
over 14,000 in low gear.
This totally got rid of the servo slapping the gears around, which is
what was making all the noise. Wasn't square bearings at all.
Cheers, Gene Heskett, CET.
--
Thanks Gene,
I could use the encoder outputs from the spindle AC Servo. It's 2500 lines or
10,000 edges per rev. But I want to use the spindle for power tapping and I
don't think my pulleys plus belt are exactly 1:1 hence the 60 slot disk on the
spindle. Pretty sure power tapping needs to know the exact speed in order to
track the Z axis.
And when I made the encoder I designed it for a 3mm end mill but accidentally
used a 4mm end mill. So the slots are 3mm and the teeth are more like about
2.5mm so the quadrature square waves are not symmetrical which likely doesn't
help either.
I'm worse than that on my lathe, watching the 60 tooth bull gear with
ats-667's, I get 240 edges/turn, but the teeth are unevenly worn from 70
years of too tight a backlash setting in the back gear resulting in its
not having two consecutive teeth the same width. The smoothing effect
of the vfd seems to paper that over and rigid tapping works well if I
can get the tap mounted properly. With std tool holders that is a PITA.
So most of my lathe threading is done with G76. Which disengages the
work on the backstroke. That does not stop the tach from wobbling about 10%.
My intention, after ball screws on XY is to make new pulleys for a toothed
belt so I can have correct 1:1. I've found the Bergerda 1800W AC Servo has
more than enough torque at low speeds for what I do so I don't need a two step
pulley setup. And therefore I can add a second toothed belt and smaller
pulleys to the spindle and an encoder.
I have a 4 step pulley in the E-400 underdrive, stays in low 99.9% of
the time. That gets me to 600 revs, throwing white hot swarf at me.
Needs a higher hp motor to go any faster, its a bronze bearing
headstock. Oil viscosity limits top speeds.
John
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
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
