Would someone discuss the type of electronic variable speed control used
in the new Jet mini and in the Mercury. TIA.
Arch

Fortiter,

After a week without an answer, I wonder: Plonked again? Asked a wrong
or boring question? Nobody cares? Nobody knows yet? Very few of our
lathes are turned by waterfalls, gasoline, steam, wind, fusion of atomic
nuclei, perpetual motion or even an arm or a leg. There are many
types of small electric motors and many ways to control and vary their
speed. All of us use electric motors, and knowing a little bit about
them might be helpful to someone, especially as recent lathes sport
electronic variable speed control. The advent of variable reluctance
methods has changed some of our notions about methods used to vary motor
speed. I started to post a primer re these methods, but quickly realized
it would be far OT, plus an arrogance to think I could simplify
something that I know little about. Hence my simple question about the
mini-jet's type of motor and speed control. Arch

Fortiter,

I don't know about the jet in particular but many of the low HP variable
speed motors were actually universal motors with a "voltage regulator" to
control the speed. I believe the carbatec lathe has this system.
This system does not work on AC induction motors. The electronic system uses
a frequency controller and a 3 phase motor. This is what my Oneway has
A third system is present on the NOVA DVR.


"Arch" wrote in message
...
After a week without an answer, I wonder: Plonked again? Asked a wrong
or boring question? Nobody cares? Nobody knows yet? Very few of our
lathes are turned by waterfalls, gasoline, steam, wind, fusion of atomic
nuclei, perpetual motion or even an arm or a leg. There are many
types of small electric motors and many ways to control and vary their
speed. All of us use electric motors, and knowing a little bit about
them might be helpful to someone, especially as recent lathes sport
electronic variable speed control. The advent of variable reluctance
methods has changed some of our notions about methods used to vary motor
speed. I started to post a primer re these methods, but quickly realized
it would be far OT, plus an arrogance to think I could simplify
something that I know little about. Hence my simple question about the
mini-jet's type of motor and speed control. Arch

Fortiter,

Greg Kulibert wrote: I don't know about the jet in particular but many of
the low HP variable speed motors were actually universal motors with a
"voltage regulator" to control the speed. (clip)
^^^^^^^^^^^^^
I have not seen the new Jet minilathe, but I will make the following comment
.. If, by "voltage regulator," you mean a variable voltage power supply, I
would bet dollars to doughnuts that's not what they do. More likely, they
use the type of control that is commonly used to control the speed of
routers: a solid-state circuit cuts down the width of the AC sine wave, to
reduce the on-time per cycle, without reducing the torque. Many of them
also use a feedback loop to sense any speed reduction, and correct it.
These are not expensive, and they produce good torque throughout the speed
range.

Variable frequency three-phase systems are quite expensive, and would not be
appropriate on a mini-lathe.