tapping

[machinist77]

Can anyone help me? I need to program a lathe to tap a metric thread and I am unsure how to calculate speeds and feeds for metric taps Any help would be most welcome.
Roger

[Geof]

Metric threads use pitch not tpi, 6 x 1 is 6mm dia. 1mm pitch, 5 x .8 is 5mm dia. 0.8mm pitch. Just convert metric pitch to inch to get feed per rev.

1mm is 0.03937",
0.8mm pitch is 0.0315"
etc.

[machinist77]

I got that figured out,but what I need is how to figure an internal thread using a tap not a threading tool.
Thanks,
Roger

[dcoupar]

Do you want an example? If so:

What lathe?
What control?
Does it have rigid tapping? Canned cycles?
What material?
What size tap?

[joecnc1234]

If you have a tapping cycle just convert your pitch to inch for inch you would use ipm feed and tpi for feed 20 threads per inch would be .050 feed per inch metric 1mm pitch would be .0394 fpi If you don't have a tapping cycle then feed in at fpi stop the spindle dwell for half a second reverse spindle and feed out. it helps to use a floating holder from a cnc mill. look in your manual to find out how to tell your machine ipm instead of ipr.

[machinist77]

ok machiine is a v turn 26 with a Fanuc oi tc controller. It has the rigid tapping. I was planning on using a spring tapping head w/collet.The thread is m6x1. If you can show me an example I can figure out all the other metric sizes I need.
Thanks
Roger

[dcoupar]

You didn't say whether you had canned cycles or not, but if you do, something like the following should work (Try it well back from the part first).

G00 G97 G99 X0 Z0.1
M29 S500 (RPM BASED ON MATERIAL)
G84 Z-1.0 F0.0394
G00 G28 U0 W0

If your machine requires IPM for rigid tapping, multiply RPM X Pitch (0.0394) to get IPM feedrate, and use G98 instead of G99.

[codyst]

Can you change to feed per rev to tap? Then your feed rate=the pitch of the tap.