HURCO KMB-1 Control Update

P values from 1.5 up to 4 are now controlling, but with an increasing frequency of oscillation the higher the P.
Time to dig out Tommy and JT's tuning guides.

The oddness is possibly due to a VFD overvoltage on rapid decceleration. 
You may need to add a braking resistor to the VFD if you need faster decceleration.

Another  possibility is to limit the spindle speed rate of change by passing
the commanded  RPM through LinuxCNC's limit2 component.

 

The vfd has a braking resistor. Now its being controlled, the issue has disappeared.
Think I just read that I should put P to zero and D to 1.

D typically makes no sense in a velocity--> velocity loop

Important ones are 
FF0 == 1

P and I

Yessir, my experiments concur.
In fact a P of 0.45 and an I of .0015 works quite well for this system.

The slowest speeds are quite a bit faster than commanded, but 1000rpm and above are fine.
This tripping of the relay is I think self inflicted, I don't believe hopping from a very high speed to a very slow one, is something you'd do in the real world without stopping the spindle to change a tool.
Next test is to see if I can orientate the spindle and even execute a tapping cycle.

Very exciting. Thanks for your guidance as ever.

I've been trying to understand why the system isn't pulling the revs down to 300, but seems ok above, so played with the ini file OUTPUT_SCALE
ini           5000      4500    3600
s.rpm                 Actual
300          450         480      490
500          600         630      700    
1000      1000       1050    1200
2000      1800       1900    2300
3000      2700       2800    3300
To me the control isn't controlling. I think it looks like P needs to be bigger, but if I raise it enough to have an effect, I get significant oscillations.
My understanding was I should raise P until it just oscillates, and then back off a little to be safe,  and lastly tune for overshoot with I. But with this method is not working for me. Is there another method please?