Controlling three phase motors

Just for my curiosity:
Would this be an application in witch i would use W as second vertical axis to adjust both 'Z'-axis independent by gcode? (could be a nice idea for my old FM4)
Mike

Hi Mike, Fehlmann certainly refer to the "coarse" vertical positioning of the milling head as the W axis.

Out of curiosity what is an FM4?

David

FM4 is an old Stadelmann mill. Similar to todays BM4
Nothing special but good enough for an old "electronics" engineer.
Mike

Ah right, I found your website Mike. Looks like you're in Switzerland.

Yes, your little mill drill has the same issue as I have with the Fehlmann. How do you control the quill Z axis - I'm guessing with a ball screw? Mine uses the quill rack which has an astonishingly small amount of backlash. The return springs also act on the quill itself rather than the pinion which means the tiny amount of backlash shouln't be a problem except with very large cuts.

If you decide to add a W axis to your coarse positioning I'd be interest to see how you go about it and how it integrates into the CNC control.

David

Yes, one of these not updated homepages... Think it over 6 years now... Yes and still with my former wife... Should invest and show new stuff. But i'm so busy and lazzy.

I'm not happy with my z backlash, at least when using big cutters, but have not yet any idea how to modify to a ballnut version. And this head is heavy whent hand-cranking upwards. Problem is that the head can swing free around the round tower-zylinder.. So maybe one day i have a super idea. Until than i enjoy what i have.
And yes, the lcnc hw/sw would be easy for me. Programming in hal is quite special, but not difficult.
Mike

Hi Mike - I did have a look at modifying my machine to a ballscrew for the Z. It's not so difficult someone over on MyCNC.UK has done it very nicely on a similar machine www.mycncuk.com/threads/651-Warco-Major-CNC-build-log/page8

Going back to my first question. The very helpful people at Fehlmann have sent drawings of the later P54 machine. Apparently for the W axis it uses the same induction motor as my machine driven by an inverter with a rotary encoder mounted on the end of the rack pionion. It doesn't sound like the most accurate way of obtaining the position of the head - even with the no doubt very accurate rack and pionion set.

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.