Re: Screwcutting Software

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<davemucha@j...> wrote:

>
> It seems that if one is controlling the spindle as a linear
> axis (servo with feedback?) and can lock the spindle to the
> Z axis for synchronized movement, it could be as simple as
> one revolution being equal to the thread pitch, then
> synchronizing the Z to move at the same rate.
>

That's a big IF. Most lathes do not treat the spindle as
a controlled axis - it's just a big beefy motor connected to
the spindle by a non-positive drive mechanism like a v-belt.

So you can't tell the spindle to turn 20 times while the
carriage moves 1 inch to make a 20 TPI thread. Instead
the spindle turns at whatever speed it wants to, and you
have the much harder task of moving the carriage in sync
with the spindle.

The spindle motor is usually around 10 times as powerfull
as the controlled axis motors, maybe even more. So it's
not a simple thing to control it like any other axis.

The power relationship holds pretty well - A Sherline
might have 20W steppers and a 200W (1/4HP) spindle. A
meduim lathe might have 200W NEMA 34 steppers and a 2000W
(3HP) spindle. And a big CNC turning center might have
axis servos approaching 1 HP with a 10HP spindle.

John Kasunich