Vic, my answer is another question, what make are they, cheapo no name or a decent brand? Thinking about it more, for one hole you may use 3 hand taps taper, 2nd & plug & only one spiral m/c tap so logically the hand taps will last longer.

Tony

Spiral flute or spiral point taps are intended for machine tapping. Tap material can vary to suit different materials. In my experience machine taps on production machines will cut well into the thousand holes when correctly chosen for purpose. But as said if you are cutting by hand and using little lubrication this may well reduce the life significantly,

I prefer spiral flute or spiral point taps depending on whether I have blind or through holes. I machine tap whenever I can because I am a lazy bastard. The life nof the tap is directly related to the quality of tap you purchase. I generally avoid Chinese or Indian imports.

Why not sharpen them ?

Roy

Try a diamond stone on he inside of the flutes

Roy