New Machine Build- How much VFD do I need?

[RP Designs]

So I am starting a retrofit on an older comet cnc mill with a Fanuc 10ma control.
I do not have 3-phase so I will be running a VFD instead of a phase converter. Currently speed control is done with a small motor which operates the variable speed pulley system, it basically turns the old manual crank. Here is what I am thinking:
I will keep the current motor set-up for speed control and run the VFD at 60hz for the most part. I will manually change the VFD for overspeed when/if I need it so that I can retain the advantages of the variable speed gearbox (torque multiplication). Now I do want to add rigid tapping, so I am assuming I will need to add an encoder to the spindle for speed/position measurement. I also assume I will need electronic braking for this which looks like an option for many VFD's. I have been looking at Hitachi and AC tech drives and am a little overwhelmed by the choices options. Also, I just don't know enough about them to make a really informed choice. I need to keep costs down, so I don't want to just go for the most featured but I don't know if I can get away with a bare bones VFD or what? Are there other brands users recommend? Any help would be appreciated.

[Al_The_Man]

You will need a VFD that use either an encoder or use an existing pulse generator on the motor shaft, if it has one, also you will need the dynamic braking option.
You will also need an encoder on the final spindle shaft.
These options are required if you want to rigid tap etc.
Other options if controlling the VFD with Sxxxx/M3/M4 codes, is outputs on the VFD that can be configured for zero speed and at speed.
I am assuming this was a vector rated motor running straight off 3 phase before?
Al.

[RP Designs]

I am not sure if the motor is vector rated (how can I tell?), it is a 3 phase 230V four pole motor.

[Al_The_Man]

Usually by the label, although most of the motors I have applied VFD's to were not Vector rated without any ill effect.
Al.

[Karl_T]

Originally Posted by RP Designs ... Now I do want to add rigid tapping, so I am assuming I will need to add an encoder to the spindle for speed/position measurement. I also assume I will need electronic braking for this which looks like an option for many VFD's. I have been looking at Hitachi ...

You didn't say which control you're using. A lot of them can not do rigid tapping. My favorite control, camsoft, does it using native galil card commands. FWIW, I used a Hitachi SJ100, electronic braking, analog voltage VFD speed control , and an encoder on the spindle.

Karl

[RP Designs]

Originally Posted by Karl_T You didn't say which control you're using. A lot of them can not do rigid tapping. My favorite control, camsoft, does it using native galil card commands. FWIW, I used a Hitachi SJ100, electronic braking, analog voltage VFD speed control , and an encoder on the spindle. Karl

Right now I am looking at using the AjaxCNC centroid control which will do rigid tapping.