Hi,
Please see the video first.

I have no idea what happened but this was working before. Now the spindle RPM jumps while running.

Machine is a mill. Spindle is a servo. I confirm the servo drive shows the RPM correctly.

But interestingly when I speed up the spindle the range of the jumping numbers narrows. I mean it gets more stable. But slower RPMs are messy.

What could cause this?

Thanks

https://www.youtube.com/watch?v=1tqyhtybhPc

Hi,
what motion controller are you using?

Motion controllers report back to Mach4 every 25ms or so, 25ms being the default cycle time of an ESS. At each cycle the motion controller will report
the number of spindle revolutions and Mach does the calculation. The problem is that the 25ms cycle time is nominal only, it might be 23ms sometimes
and 28ms at other times, with consequent variance of the calculated rpm. In most cases the displayed number is averaged. I would guess that somehow
the averaging strategy has changed.

Craig

Hi,

Motion controller is Pokeys 57E on M16D. I didn't play with Pokeys settings for months.

Hi,
I doubt that anything has changed in the PoKeys, I asked so I could find out what the cycle time was.

I suspect if there is a change it will be in Mach4. If  I recall there is a post on the forum which talked about the averaging applied to the spindle speed DRO,
haven't had any luck finding it so far.

The two things which could affect the DRO in the manner that you have described are 1) the motion controller cycle time is changing, maybe some other process or software
on the PC assuming priority that is causing the motion control plugin to run at odd intervals, 2) the averaging applied to the numeric data has somehow altered.

Craig

I'm writing a module for my Arduino based pendant but it's just an external .lua file.

Which parts in Mach4 I can check to see if I can fix?

Hi,

Which parts in Mach4 I can check to see if I can fix?

At this stage, I don't know, I'm still trying to find the post about it. I'm hoping someone may remember and chime in.

Craig

Is this the thread you are looking for?
https://www.machsupport.com/forum/index.php?topic=35694.0

Hi,

Quote

Which parts in Mach4 I can check to see if I can fix?

At this stage, I don't know, I'm still trying to find the post about it. I'm hoping someone may remember and chime in.

Craig

Hi Azalin,
I remember hat thread, it was a few years ago now, but no that is not the thread I was thinking of.

If I recall correctly there is a setting, I believe within Mach, that governs the time constant of the averaging algorithm
displaying the spindle rpm.

Craig

It's ok Craig.

This is really odd. I played with the numbers in both Mach4 and PoKeys. Nothing worked.

https://www.youtube.com/watch?v=3kztXPBJ3bs

Edit: There is an encoder test screen in PoKeys config app. When I spin the spindle the spped calculation appears to be correct so I think the problem is in Mach4.

Hi Craig,

https://www.machsupport.com/forum/index.php?topic=42282.0

Is this the one?

Hi Azalin,
I remember hat thread, it was a few years ago now, but no that is not the thread I was thinking of.