Re: cutting threads on lathe

Doug - The parts don't need to be vertical, then can be horizontal
and milled without a rotary table of you can position the spindle
horizontally and adjust backlash on the z-axis. You will also need
to swap the Z- and X-axis stepper motors (or connections at the
controller). Charles Hixon

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "doug98105"
<doug.rasmussen@c...> wrote:

> Jon,
>
> Yeah, it'll work, been there, done that.
>
> But, don't forget his parts are 12" long. Does his mill have the
> needed distance from table to spindle to stand that long a part on
> end?
>
> Speaking of milling threads....before I had a machine that would

do

> helical milling I setup a spread sheet to generate helical paths
> made up of short line segments. What was a little special about

my

> calculations was I'd input the diameter, pitch and a guess at the
> number of line segments in 360 degrees and it would generate the
> code, plus give the max chord deviation from true circle. By

trying

> different line counts you could come up with an acceptable

deviation

> value. If it was a precision thread the deviation could be
> correlated to the thread pitch limits to keep the thread "legal".
>
> Here's a little thread milling trivia...when you buy carbide

thread

> milling inserts why do they have different inserts for internal
> threads and for external threads when the pitch is the same for

both?

>
> Doug
>
>
>
>
>
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...>

wrote:

> >
> >
> > doug98105 wrote:
> >
> > >fine',
> > >
> > >If you only intend to use the lathe for threading the ends of
> your
> > >pipe then save yourself some time/money.
> > >
> > >Buy a small turret lathe or conventional lathe with bed turret
> and
> > >thread with a die head. It'll be as fast or faster than CNC.
> > >
> > >
> > WAIT a MINUTE! He can do it with the existing equipment he
> > has, which is a 3-axis CNC mill! I got a little single-row

thread

> > mill some time ago to do some odd internal threads. But, thread
> > milling can be done on outside threads, too. With a little

program

> > to crank out the arcs, you can cut beautiful tapered threads in a
> > few seconds. If you need a couple of seconds to wipe off the
> > chips while it is doing the next one, it should be fine. With

the

> > CNC milling of the threads, there's no technique to getting the
> > right depth each time. Also, with a suitable clamp to hold a

bunch

> > of parts, he can line up the parts, and the machine can run down
> the
> > row tapping them all in a few minutes.
> >
> > Jon