Rigid Tapping Metric Threads

[GM81]

I have never tried rigid tapping metric threads before, I am programing in Inches, will a simple conversion work?

Normally I would just tap them out of the machine but I have over 40 m4x0.7 holes on this particular part. Anyone tried this?

[DSL PWR]

Just do the conversion and it should all work out just fine. The tap won't care about a couple of tenths...

[DareBee]

Works for me

[davereagan]

No need to be off a couple tenths. The feed for M4 x .7 is .0275591" per rev.

[Neal]

Just to clarify the feed rates for the Fadal control, the control will round the feed rates to it max default decimal places. Using excess of 4 decimals places on the "F" code means nothing to the control.

Neal

[CaseyCAM]

Originally Posted by Neal Just to clarify the feed rates for the Fadal control, the control will round the feed rates to it max default decimal places. Using excess of 4 decimals places on the "F" code means nothing to the control. Neal

whether the control cares or not I been rigid tapping for over 7 years and only use .123"

tenths are not enough to break a tap even in a solid tool collet holder.

if you wanna be really certain just make sure your post rounds off the pitch decimal to the nearest thou

[Neal]

Programming CNC controls since 1978 I have found that various controls have the capacity to use different "F" code values for threading. For isntance the Fanuc lathe control can use 6 digits with an option applied.
The only concern I would have using more than 3 decimal palces it if I was creating a dry seal thread with a "J" root.
Neal

[GM81]

Thanks for the info, it all worked out well. I went ahead and tried a hole in a piece of scrap just to be sure.

[JOHN PARSONS]

4 Divided by 25.4= .1574
.7 divided by 25.4= .0275
.1574-.0275= .1299 is the minor dia.
1 divided by .0275= 36. is threads per inch.
I don't usually thread mill small holes unless it's tough material.