On 5/28/25 23:32, John Dammeyer wrote:
I've been asked how many lines an encoder on the spindle should have for
LinuxCNC. I have a disk I made with 60 slots and IIRC someone else on this
forum uses a gear tooth sensor. So a 400 or 600 line encoder isn't really
required but likely there is a point where extra lines don't make any
difference.
Now with the MESA the encoder edges are counted in hardware so in reality
likely the MOTMOD grabs the number every period and uses that for the
trajectory planning with respect to power tapping.
So here's the question. Are the encoder counts acquired from the MESA
hardware done on the BASE PERIOD or SERVO PERIOD?
Normally you wouldn't be power tapping at 3000 RPM so at slower speeds
higher resolution might be useful but at which point is there a tradeoff?
Thanks
John
Not that I have found, John. I did run from a 64 slot disk on the
spindle on my GO704 but the spindle sounded like the ball bearings were
square! So as a test, I made an extension for the rear of the OEM
motor, a PMDC 1hp I am pushing to around 3hp. And put a 1000 ppr encoder
on it, after the disk I had made for the spindle was destroyed. Made
the appropriate hal changes. Turns out the 64 slot optical was the cause
of all the bad bearing noise as it was jerking the motor around.
I'm still using the test method almost a decade later.
My hal adjustments are moderately complex but I can fwd the hal & ini
stuff fairly easily if you want to study it. Send me a PM. I'm assuming
you have opto-less breakout board to the complete conversion is a bit
complex. I'm using a 5i25 and a 7i76d and a modified for speed
sainsmart BOB. Modified by removing the opto stuff, and bypassing them,
enabling the much higher frequency edges from the omron encoder direct
driven from the motor to be faithfully submitted to the 5i25. Tach works
to 100% motor speed, topping at 3k rpms. OEM control tossed, pico
pwm-servo drives the motor from an isolated 125 volt supply good for 20
amps. 90 volt motor, still on OEM brushes.
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
