Controlling three phase motors

Agathon wrote: I'm still a little puzzled about how the induction motor can be made to position the head using the encoder and inverter set up.

Think of it as a spindle used for rigid tapping.

Mmm... I'd like to do that too, I'll do some research. Thanks Tommy

You are welcomed, always.

On further thought, what about using a linear encoder? On the Picomax 54 the rotary encoder's mounted on the pinion shaft so it's not counting the motor revolutions. On the Picomax 55 is an almost identical machine, but it looks like it might use a linear encoder to feedback the W position to the CNC.

Hi David where are you located? Switzerland too, or Belgium?
I like this British idea, good idea might solve my demands , will have some sleep over such a construction. THX.

For your second vertical axis i would see it as real w axis. With joint and axis. If you go the mesa path, and in my eyes thats the only professional way (never parport for a real machine), you might find a way to mount a scale and use mesa decoder to get precicely controlled hight. This would in my eyes be a simple augmentation of a 3-axis configuration. Also your gcode generator must not know much about W.
I would use gmoccapy with tool length measurement.
Mike

Hi Mike

I'm in the UK - I've run a little business on the side for the last twenty or so years called Anglo-Swiss Tools - www.anglo-swiss-tools.co.uk . I'm more of an academic these days.

Thanks for encouraging words about the W axis. I'm definitely going to go down the Mesa route - probably the 7i76e. I'm sure I'll post again when I get round to setting it all up.