Not sure about the manual threading option.

There is an encoder mounted on the spindle that sends to the CNC
controler the speed and position of the spindle. The controler then
coorinates the axises drives with the speed and position of the spindle
to cut a thread. When threading, it picks the same point on rotation of
the work to start the cut. The canned threading cycle will then pick
the right starting point to distribute the cutting load.
See here for an explanation of the threading cycle
http://www.manufacturingcenter.com/t...504tooling.asp

Todd Rearick wrote:

OK, so when one adds CNC to a mill or lathe, it's a good idea to upgrade to
ballscrews in order to eliminate backlash.....sounds reasonable to me, but
I'm a little confused about what this does for the leadscrew of a lathe. Is
there a special ballscrew that can be engaged/disengaged like a T-nut? I
can't quite figure out how anyone would thread with a lathe after replacing
the normal leadscrew with a ballscrew....seems like manual threading would
be completely out after that.

I suppose the CNC controller could perform the threading operation, but it
would need to know the spindle speed and phase...how is this normally done?

Todd



--
James P Crombie
Slemon Park, PEI
Canada
Machinist - 3D Cad Design - Amateur Astronomer

http://www.jamescrombie.com