"Harold and Susan Vordos" wrote in message
"Gerald Miller" wrote in message
snip-----

Came by a couple of 1/2" LH thread nuts, so decided to
make shaft
adaptors for motors with 1/2" shafts since all of the
available ones
are RH thread. I got to the point of cutting the
threads, did my first
pass and checked the scratch against the mating male
thread - didn't
quite agree; the original thread was 1/2 - 24, so now I
have a funny
spot every 6th crest.
Gerry :-)}
London, Canada

Heh!
Can't tell you how many times I've done that. Nice thing
is, the "funny
spot" virtually disappears if you make a habit of making
your first pass a
shallow one. A thou or two is plenty.

In spite of my years of experience, or maybe because of
them, dunno, I
always take a shadow cut when chasing threads. Just deep
enough to allow a
match with the pitch gage. It's too damned easy to miss
a setting,
especially on my lathe, where I've messed with the ratio,
having cut all the
feeds and threads in half. I like light feeds for
finishing and found my
Graziano too fast in that regard. I've lived with the
changed ratio since
1967----but still screw up occasionally. Maybe a function
of getting old,
eh?

Harold



A couple years ago I made a thread toy called a puzzle nut.
It was cut
at 9 tpi double start. Since this is an odd number thread
and it was
being doneon a SB model A 9 inch I used the numbers on the
dial for one groove and the unnumbered marks for the other
groove.
Did both the male and the female this way. The nut was cut
in half
and red loctited to the ends of the male section. It worked
nice and
looked like 18 tpi but the nut moved fast from end to end.
So then
I decided to try a triple! For that I started with a longer
rod with a
dowel pin in the side so it would rest against a chuck jaw.
Cut the
groove at 9 tpi as before but for the next groove I moved
the rod pin
to the next jaw and then the third jaw to make a triple
start thread!
This one was really fast moving! Sure acted strange rolling
than nut
back and forth as the thread looked to be fine at 27 tpi but
really
hauled ass from end to end! That was fun......;)
phil