Spindle PID control

For a velocty PID loop probably the most important part is FF0
(if the PID feedback, command and output are all in RPM, FF0 should be 1.0)

If you have only FF0(all other PID terms=0), you are running open loop
(because the PID output is just FF0*Command)

Using the FF0 feedforward term make the PID output approximately correct before any
feedpack is applied. This makes the P and I terms have less work to do...

You will always get oscillation on a PID system if you increase any P,I,D term too high
I would try using less P (say 2) and then see how high an I term you can have and stay stable
D term should not be needed