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kernal frequency issue with combo of servo's and steppers
Posted:
Sun Dec 17, 2023 4:54 pmby mark68
I could do with some advise on this please,
To get the speed from my servo's I need to run the kernel at 400khz otherwise speed is throttled too much, but i have a 4th axis rotary which I mount when required on the machine for turned work this has a nema 23 stepper motor which won't run at 400khz frequency. (took me a while to figure this out as I was convinced the driver/motor or my wiring was the issue.)
Options as I see them but please advise if there is another way as I'm not keen on either.
1-Reduce the kernal to 200khz everytime I use the rotary. (will i need to recalibrate steps per?)
2-Buy a small nema 23 size servo and driver to suit.
Re: kernal frequency issue with combo of servo's and stepper
Posted:
Mon Dec 18, 2023 12:26 pmby ger21
3) Make two separate profiles, one with the rotary and one without, each with different kernel frequency.
4) Use electronic gearing in the servos.
Re: kernal frequency issue with combo of servo's and stepper
Posted:
Mon Dec 18, 2023 9:43 pmby mark68
Thanks, I'm new to servo set up.
Gearing page of Servo manual attached, am i correct in thinking I need to double the ratio that is currently set to one. Going from 400khz to 200 khz setting in Uccnc.
So Pr0.09 1st numerator of electronic gear could be set to 4 and Pr0.10 denominator of electronic gear set to 2 = gear ratio of 2. From what i gather the actual numbers don't matter as long as the division result =2.
Re: kernal frequency issue with combo of servo's and stepper
Posted:
Sat Mar 23, 2024 10:10 pmby NeeqOne
mark68 wrote:Thanks, I'm new to servo set up.
Gearing page of Servo manual attached, am i correct in thinking I need to double the ratio that is currently set to one. Going from 400khz to 200 khz setting in Uccnc.
So Pr0.09 1st numerator of electronic gear could be set to 4 and Pr0.10 denominator of electronic gear set to 2 = gear ratio of 2. From what i gather the actual numbers don't matter as long as the division result =2.
Did setting the electronic gear ratio to 2 worked for you? Did you have to changed anything? I am using similar servo and experiencing the same issue. Will you mind sharing you parameter list with me? Thanks.
Re: kernal frequency issue with combo of servo's and stepper
Posted:
Sat Mar 23, 2024 10:32 pmby mark68
NeeqOne wrote:
Did setting the electronic gear ratio to 2 worked for you? Did you have to changed anything? I am using similar servo and experiencing the same issue. Will you mind sharing you parameter list with me? Thanks.
I didn't change them in the end as I found a driver for the rotary axis that worked at 400khz. If you do work out the steps then I'd like to know, sorry for not been too helpful.
Re: kernal frequency issue with combo of servo's and stepper
Posted:
Sun Mar 24, 2024 1:50 pmby NeeqOne
Find attached a python code I wrote for computing the numerator and denominator for the ac servo drove.