Command reversing spindle

[aaroncale_]

Everything behaves normally under standard RPM commands, but the moment I switch to G96, the spindle starts reacting in reverse and instead of adjusting speed the way it should, it does the exact opposite almost like the logic got flipped. I’ve double checked the wiring to the VFD and the basic parameters, but so far nothing stands out as obviously wrong. I dont know whether there's a parameter mismatch between the controller and spindle, or something in the analog output scaling isn’t lining up the way it should
Would appreciate any help please, TIA

 

[c_pellegrin0]

If G96 is making the spindle act weird, check if the machine is reading the surface speed wrong because the tool size wasn’t set right. Some setups need you to enter the tool diameter or offset by hand to get the right RPM. What controller and post are you using?

 

[Prince_Gotha]

G96 weirdness almost always comes down to scaling mismatch. The control might think zero volts = max RPM. Swap your analog output polarity in the VFD settings and test at low speed. If it fixes it, you know what’s up. Happened to my old Centroid setup too.

 

[Gimm3gimlet]

If G96 is making the spindle act weird, check if the machine is reading the surface speed wrong because the tool size wasn’t set right. Some setups need you to enter the tool diameter or offset by hand to get the right RPM. What controller and post are you using?

Sounds like a parameter mismatch. Forget the VFD wiring for a second. Go straight to the control side parameters for the spindle drive.
You mentioned the logic is flipped. Look for the parameter that defines the G96 direction/polarity or the one that scales the analog output for $G96. On some controls, if it's set to '1' instead of '-1' or vice versa, it'll send a negative speed signal when it should be positive. What control is this (Fanuc, Haas, Siemens)?

 

[Pisc06uck]

Check your code for a G50 S command (Maximum Spindle RPM limit). If this value is set incorrectly or missing, the spindle can try to chase an impossibly high RPM as the tool approaches the center line, leading to erratic behaviour as the controller hits its limits.