"Bob La Londe" wrote in message
...
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 70...
"Bob La Londe" fired this volley in news:1HU0r.8235$I%
:

??? Didn't you say you already basically ruined as a regular tap ???

Yeah, but it's my only one, and it's "sort of" working as a threading
mill
right now. Just don't want to make it worse.

I started out with a 3/16" boring bar, Bob. It was too flexible, and
just
sang to beat the band. The tap cuts quietly.

I'll try making up a LH boring bar, and cutting in climb.

Lloyd


You can always make a much bigger boring bar.


I have a single point one I made up by off-hand grinding an old 5/8 many
years ago that I still occasionally use for 3/4 and larger npt--it takes
several minutes to actually machine a thread this way as opposed to only
taking a few seconds when an actual thread mill that has multiple teeth is
used....

Also, where a single point tool is used, you're still probably better off to
finish by chasing with an actual tap afterwards.