I found with aluminum forming and spiral flute both worked nicely. I get a
lot more holes out of a forming tap than a spiral flute tap.

However, I was machine tapping some brass the other day and found the
forming tap hardly made an impression. I thought maybe my cheap drill bit
was the problem and over sized the hole so on the next one I used the next
smaller bit (only a couple thousandths) and promptly snapped off the forming
tap on the second hole. Oops! I forgot to reset the clutch, but since this
was a brand new experience...

Since I had one barely formed hole and one formed hole I decided to see how
the screws went in even though the work piece was ruined. The one that was
barely formed was very hard to put the screw in, and when I removed the
screw I saw that the threads had now formed that had not formed before.
Weird. The one that was drilled undersize and formed the screw went in much
easier. Weird.

Anyway, I have decided for my application for the size I am threading I do
not think brass is suitable for forming. (8-32 H3) I do want my taps to
last as long as possible before replacement though. I do not have any
spiral point taps, but from looking at pictures it would seem they have more
meat to them than spiral flute taps.

Is a spiral point (in general) stronger than a spiral flute tap?

Does a spiral point tap (assume both are sharp) cut as easy as a spiral
flute tap?

On Thu, 10 Jan 2013 10:28:30 -0700, "Bob La Londe"
wrote:


Does a spiral point tap (assume both are sharp) cut as easy as a spiral
flute tap?


Most S.P. taps are plug style, while most S.F. taps are bottom or
semi-bottom style. I find S.F. taps take a little more power because
of this. I usually don't like using S.F. taps because of this,
especially in harder materials, Maybe because I'm still little old
school and was taught to only use a bottom tap to finish holes that
were already tapped close to bottom. Just scares me to run a bottom
tap into a peice of steel under power.

I never used a forming tap in anything other than aluminum, what is
the hardness of the brass. Maybe it's just not malleable enough?

Remove 333 to reply.
Randy

"Randy333" wrote in message
...
On Thu, 10 Jan 2013 10:28:30 -0700, "Bob La Londe"
wrote:


Does a spiral point tap (assume both are sharp) cut as easy as a spiral
flute tap?


Most S.P. taps are plug style, while most S.F. taps are bottom or
semi-bottom style. I find S.F. taps take a little more power because
of this. I usually don't like using S.F. taps because of this,
especially in harder materials, Maybe because I'm still little old
school and was taught to only use a bottom tap to finish holes that
were already tapped close to bottom. Just scares me to run a bottom
tap into a peice of steel under power.

I never used a forming tap in anything other than aluminum, what is
the hardness of the brass. Maybe it's just not malleable enough?

That was my initial conclusion. Upon further reading forming taps are only
recommended for dead soft brass by several source I read.

"Randy333" wrote in message
...
On Thu, 10 Jan 2013 10:28:30 -0700, "Bob La Londe"
wrote:


Does a spiral point tap (assume both are sharp) cut as easy as a spiral
flute tap?


Most S.P. taps are plug style, while most S.F. taps are bottom or
semi-bottom style. I find S.F. taps take a little more power because
of this. I usually don't like using S.F. taps because of this,
especially in harder materials, Maybe because I'm still little old
school and was taught to only use a bottom tap to finish holes that
were already tapped close to bottom. Just scares me to run a bottom
tap into a peice of steel under power.

I never used a forming tap in anything other than aluminum, what is
the hardness of the brass. Maybe it's just not malleable enough?

That sounds about spot on. After doing more research it seems only dead
soft brass is suitable for forming.