Myford 7, 3 phase motor other CNC questions.

[JohnHaine]

Joe,

Yes you're right, I see that Arc don't sell ball screws any more. I have ordered other stuff from Zapp Automation who seem to be very good, and they offer machining services for ball screws I think.

No, he doesn't use a stepper driven spindle. Nor does Tony I think? IIRC Tony uses an electronic lead screw driver - http://medw.co.uk/wiki/index.php?page=ELS+Price+List - which uses a spindle sensor and synchronises the z drive to it. Frankly I don't see the point when you can use a full cnc system for not much more money.

Mach 3 and LinuxCNC both accept spindle pulses and synchronise the feed for screw cutting. Cncyourmyford uses LinuxCNC as this seems to give better results, as it has two sensors, giving one pulse per rev to sync the thread, and a larger number of pulses per thread (e.g. 64) to monitor the spindle speed. His package includes a ready configured LinuxCNC image. I use Mach3 and so far haven't had much luck with threading, I'm going to try the Linux version sometime at least on the lathe. Mach has only a single pulse per rev sensor and can't cope very well if the spindle slows when the cut starts.