Tapping aluminum. Spiral flute or not ?

[Argofanatic]

Hi, several years ago I discovered just how magnificent spiral fluted taps were for small holes in aluminum. Since then that's all I use.
Now I need to tap a bunch of 12mm (1/2 inch) holes. Is there much of a difference between spiral fluted and regular taps for larger hole sizes ?
I haven't purchased that size tap yet.

Thanks,
Marc.

[dertsap]

spiral flt should work no problem , i wouldn t recommend using spiral point on blind holes on alum.
what about trying roll taps ? i ve had much success with them

[ajl6549]

Rolled thrds. tend to be stronger, esp. in aluminium.

[jackson]

Originally Posted by ajl6549 Rolled thrds. tend to be stronger, esp. in aluminium.

yeah i have had the same expireanc the roll tap or form tap do very well but the spiral should work

[ajl6549]

Oh it'll definitely work, and well.

[RICHARD ZASTROW]

I vote for the rolled threads (form taps). Like I said in another thread, I live about 1 mile from Balax's plant.

[Argofanatic]

Thanks for the info. I'll buy a forming tap.

I should have mentioned earlier that my experience was with small holes 4-40 and I kept snapping taps, that's when I discovered spiral flutes.

Cheers.
Marc.

[dertsap]

Originally Posted by Argofanatic Thanks for the info. I'll buy a forming tap. I should have mentioned earlier that my experience was with small holes 4-40 and I kept snapping taps, that's when I discovered spiral flutes. Cheers. Marc.

even better time to use roll taps , the small sizes work great , i've done many parts with lots of 2-56 , 4-40 tapped holes in them and rarely one breaks ,
roll taps also work pretty good on larger tapped holes (1/4" + ) in stainless and such where other spiral point and spiral flt fail , didn t beleave it till i tryed it

[ajl6549]

4-40 wow thats small what s + f are you using?

[dertsap]

on a decent machine ,anywhere between 250 to1500 rpm on aluminum

[phantomcow2]

Forming taps are great for aluminum, we use them almost exclusively for all rigid tapping operations. We routinely tap 2-56 with almost no breakage using forming taps.

[wildcat]

Are the same size holes drilled for forming taps as for fluted taps? Do forming taps work fine for hand tapping and in a benchtop tapping tool?