Hi Hood
Thanks for your reply.
To hob a gear using a helical hob (as used by commercial gear cutters) the Z axis will be fixed, the Y axis will provide depth of cut and the x axis feed, all independent of the rotation of the rotary or A axis.
Correct me if I am wrong, but I gather that Mach 3 will only accept 1 pulse per spindle rev when thread cutting.
So thinking about it a bit more, if you were to hob say a 10 tooth gear, for each rev of the spindle the rotary axis has to rotate 36 deg and in true sync with each fractional turn of the spindle.
I am beginning to think that the pulse rate per rev of the spindle has to be high for this to work reasonably accurately, which I don't think Mach can do.
So, I think your rely has helped me answer my own question and as you say, it won't give true accurate sync between the spindle speed and rotary axis. So no, mach would not be suitable.
The compucut system does actually have a very high pulse rate per spindle rev., so compucut it will have to be then.
Thanks again
Nigel