metric tapping

[kurt_laughton]

i am trying to tap M8x1.25 holes in mild steel how do i figure out speeds and feeds for rigid tapping on a standard machine??? Thanks For the help!

[Geof]

1.25mm pitch is 0.0492". If you use 1000 rpm the feed is 49.2 ipm.

[kurt_laughton]

I Figured It Out But Thats I Got 49.3 @1000rpms And It Worked!

[psychomill]

Since you got the right answer, you probably figurred it out. On a metric tap, the pitch is designated after the diameter. The difference being that on a standard thread, the pitch is threads per inch. So, just take any metric pitch and divide by 25.4, you have the inch conversion. If you program for IPR, you have your answer. Multiply by RPM if you feed in IPM and run.

[jbird68]

That good if you are running in inch mode. but if you are programming in metric mode, what is the MM per min. I just started learning learning how to program a Tree 325 Mill. I can convert inch to metric but not sure how to program speed and feeds for metric tapping cycles. M8, M10, etc.

[Geof]

RPM multiplied by lead.

1.25mm per revolution is 1250mm per minute at 1000rpm.