Speed & feed calculation for metric taps...

[?Mark]

My question is where it is getting the calculations from?

Seems like they're off by a bit. Not a big deal, but never seen it with inch taps.

 

Example:

M5x0.8 MC gives S507 for F16.(should be S508)

 

Similarly for few other taps that I checked...

As I said, the difference is minimal and will most likely work fine, but I think number rounding is screwed up somewhere...

 

[High Sierra Plastics]

Yeah, it looks to me like it's rounding off to .0315 per rev, which would give you a 507ss. I think, your machine as far as the percision goes, it shouldn't make a difference if your using ridgid tapping. Even less if your using a floating holder. If you look at the average it's better to be running at 507 since the machine only goes 3 decimal places on the feed.

 

Henri

[Psychomill]

Hey Mark,.... just feed your taps in IPR instead and ignore the calculations.... Let your machine figure it out..