Need Help!- Mach3 Rigid Tapping

[jwantulok]

Anyone have any thoughts on this setup for rigid tapping:

Spindle = 7.5HP 3ph 220VAC Induction Motor
VFD = Automation Direct GS3 Sensorless Vector using +/- 10V Velocity Ctrl
Encoder connected to spindle Line Cnt to be determined
Rutex 2040 Feed +/- 10 to VFD and Reads Encoder
Smooth Stepper feeds R2040 Step/Dir Signals
Mach3 talks to Smooth Stepper on USB
Spindle is setup as addtional Axis and S/D Control as in other threads.
Main Difference is use of Induction Motor/VFD as a "Servo"
Will it Work????

[ger21]

Mach3 doesn't support rigid tapping.

[jwantulok]

What about the setups I've read incorporating setting the spindle up as both a S/D controlled spindle and an angular axis, then writing macros. Not conventional, but maybe it would get the job done?? My prime concern is the use of a VFD and Induction motor for positioning. Any thoughts??

[MJ_cnc]

I think the position aspect out of a VFD is exactly your problem. From what I've seen, VFD's handle speed well, but not position. Think of pumps, fans, and speed control.

To control position, that points to a servo. I can't imagine the cost of a servo comparable to your 7hp motor and vfd.

I did a little looking around on the Mach 3 arcsoft site. I'm looking at using a Galil motion controller and there's a thread there that says Rigid tapping is in the galil code, so it looks like it can be done. Rigid tapping is what's called a following application and the only way I know how to do that is to control position.

To add further, I think the problem is that the cost of servo's is not cost effective compared to the VFD's. Therefore, if you really, really need it, you can do it, but he cost will be more than what most really 'need.'

Mark