CNC Threading

[metalworker]

I am thinking of adding controlls to a 9x20 chinese lathe i have, due to space requirements i have to work with this and nothing much bigger.

Anyways, one of my main parts i wish to make has threads. I need to cut class 2 1 3/8-20 unef. The lathes i program at work this is easy to do. I understand mach2 does threading, and so does turbo cnc.

What are the pros and cons of either? Iwas told that mach 2 only checks spindle speed once makes the pass, and doesnt account for speed loss during the cut.

Do i need to have the same pitch ballscrew for the Z and X to do radius work?

Thanks

[RotarySMP]

I have no experience with Mach 2 (but have only heard good reviews).

I have been a beta tester for TurboCNC and am very impressed by it. For TurboCNC, there is no requirement for both axis to have the same lead (I have 3mm lead on X and 4 on Z).

TurboCNC uses a 1/rev spindle encoder for threading and needs about three thread's distance to get well sync'd before running onto the work. This can be an issue with smaller threads on a long shaft supported by the live center.

During the cut you can hear it altering Z speed to keep sync'd to the changing spindle speed. You want a reasonably fast Z axis, with plenty of acceleration.

Realistically, both controllers are step and direction, so the hardware is the same. TurboCNC is shareware, and cost nothing to try for as long as you want (the developers desere the $60 registration fee). If you don't like it or DOS, then you can change to Mach2 with no loss.