Lathe with C-axis and live tooling

Hi guys,

I am almost done building a CNC gangtool lathe. I am using AC servos for X and Z as well as a large one for the spindle, so I will have C axis control. I am also planning on getting a spindle with a vfd for live tooling. (like the one in the link below) I am not sure how to program the live tooling portion of it and also how to program switching from turning mode to C axis control.

Live Tooling Spindle:
www.ebay.com/itm/WATER-COOLED-1-5KW-USA-...b:g:UEcAAOxygPtSyRIs

Thanks,
Tosh

See this:

forum.linuxcnc.org/forum/38-general-linu...-done-need-some-help

Basically linuxCNC does not natively support a C axis "out of the box", because when the spindle is working the C axis also will try to maintain the last position that it was commanded to.
Mr Andy reply is for what I know the only possibility that does not imply the change on linuxcnc source code. However each time that the you change between spindle mode and C mode, the chuck would need to index itself.

Just another thing: That spindle that you see in ebay is good for engraving. Do not expect more than that because the speed is probably to high (normally they are quite speedy - you should check, I took a look and I saw nothing related with speed).
In my machine, a professional grade machine with pre build live tooling the live tool motor is 3phase 6 poles, this means that the torque will be higher at about 900 rpm (for 50Hz), that is a good milling speed for mid range tools. The range of the milling speed can be set from 50 to 3000 rpm.

That seems a lot of work!

How this addresses the issue related with the C axis? C axis already works out of the box (with the problem reported on my/jtc post before that you also commented).
From the description of your patch it allows the use of multiple spindles, but on the issue of a lathe with a C axis + live tooling, there are not multiple spindles available, basically the live tool is a simple tool commanded in X and Z (plus the C that is the same spindle). Maybe I am seeing less than I should?

I don't anticipate any problems switching or running the C axis, even if it has to re-index the spindle every time you switch. In terms of live tooling I still haven't decided what I am going to do, however I may run two live tools. One for milling purposes, no feedback needed but speed control in software would be nice. The second live tool would be for rigid taping. Another option is use a single servo to run two parallel spindles, one for milling and one for rigid taping. In that option I guess I would want control like the spindle and C axis. Just for a different axis.