On Thu, 17 May 2007 16:45:57 -0700, Jimbo wrote:

I was wondering if it is possible to in any way to slow down the motor
on the Jet without damage to it.

It would be possible to make a "souped up light dimmer" which is very
doable but will it cause damage to the motor?

After getting into turning I wish I would have bought a lathe that
goes slower for larger pieces.

As others have noted, the dimmer switch is probably a bad idea, but
depending on how badly you want the thing to go slower, I've got an
option for you.

It you get yourself a left-hand tap that matches your headstock
spindle on the outboard side, you could laminate a couple of pieces of
plywood together to make a big pulley. Tap the center, and thread it
on to the spindle, then turn it to the size desired and turn the
groove for the v-belt.

Then, get yourself another motor. It doesn't have to be fancy, and a
lot of lathes don't have a huge amount of horsepower. If you were to
dig up something like a 1/3 or 1/2 hp electric motor from an old
appliance, that might do the trick.

You'll have to mount the motor to something, and get a small pulley on
it. When you want to turn slow, release the tension on your main belt
so that the spindle will turn easily, and won't burn up your main
belt, and hook up the secondary motor.

A regular electric motor turns at 3450 rpm, IIRC. Reduction in speed
is a direct ratio between the two pulley sizes. Don't hold me to the
math, but if you were to have a 2" pulley on your secondary motor, and
a 20" pulley on the outboard side of your lathe, you should get a
spindle speed of 345 rpm. You get the idea, anyhow- the larger the
difference between the small pulley on the motor and the large pulley
on the spindle, the slower the lathe will turn.

It'd be kind of a goofy looking contraption, but it's pretty
straightforward and can be done cheap- without risking damage to your
lathe's original motor. If you want it going really slow, with
smaller pulleys, make a double or triple-reduction setup, mounted on a
bit of plywood or a board. If you need the slow speed for outboard
turning, put the pulley on the inboard side with a right-hand tap.

Or, skip the tap entirely, and mount the pulley on a faceplate-
whichever makes more sense to you. If you're really safety concious,
make a plexiglass guard to cover the pulleys and belt.

That would be the way I'd do it, if I wanted to do such a thing.

"Prometheus" wrote: (clip) A regular electric motor turns at 3450 rpm,
IIRC. (clip)
^^^^^^^^^^^^^^^^^^^
Most fractional HP motors run at half that speed: 1725. If your motor does
actually run at 3450, you can cut the speed in half easily by just changing
motors. However, most lathe manufacturers try to provide as low a speed as
they can with a practical pulley ratio and the more common motor RPM.

Rather than going to the trouble of mounting an extra motor, with all its
complications, consider the possibity of mounting a countershaft and using
the same motor.

I would start looking for a lathe that runs slower, or shopping for a
variable speed drive.

"Leo Lichtman" wrote in message
...

"Prometheus" wrote: (clip) A regular electric motor turns at 3450 rpm,
IIRC. (clip)
^^^^^^^^^^^^^^^^^^^
Most fractional HP motors run at half that speed: 1725. If your motor
does actually run at 3450, you can cut the speed in half easily by just
changing motors. However, most lathe manufacturers try to provide as low
a speed as they can with a practical pulley ratio and the more common
motor RPM.

Rather than going to the trouble of mounting an extra motor, with all its
complications, consider the possibity of mounting a countershaft and using
the same motor.

I would start looking for a lathe that runs slower, or shopping for a
variable speed drive.

Leo, Arch too, the 1442 is a Reeves. Neither idea put forward works
particularly easily or well.

Shopping will.

On Sat, 19 May 2007 21:00:48 GMT, "George" wrote:


"Leo Lichtman" wrote in message
...

"Prometheus" wrote: (clip) A regular electric motor turns at 3450 rpm,
IIRC. (clip)
^^^^^^^^^^^^^^^^^^^
Most fractional HP motors run at half that speed: 1725. If your motor
does actually run at 3450, you can cut the speed in half easily by just
changing motors. However, most lathe manufacturers try to provide as low
a speed as they can with a practical pulley ratio and the more common
motor RPM.

Rather than going to the trouble of mounting an extra motor, with all its
complications, consider the possibity of mounting a countershaft and using
the same motor.

I would start looking for a lathe that runs slower, or shopping for a
variable speed drive.

Leo, Arch too, the 1442 is a Reeves. Neither idea put forward works
particularly easily or well.

Shopping will.

Prometheus has a good idea and it does sound like a lot of work. I do
however have an extra motor from my old lathe - montgomery wards
power-craft. I think would rather turn more at this point than try to
add extra pulleys.

I will keep my larger wood pieces until such time I either get more
ambitious to try the pulley scenerio or spend $$$ for the right lathe.

Thanks eveyone!

Jimbo

Jimbo wrote:

I will keep my larger wood pieces until such time I either get more
ambitious to try the pulley scenerio or spend $$$ for the right lathe.

Thanks eveyone!

Jimbo

That's the same decision I came to when I was given two huge chunks of
cherry*. They have been slowly drying in a corner of my basement for
three years now. I figure that by the time I have the skills to do
justice to them I will probably also have the equipment.

So far I am still turning on a HF 12x36. :-(

Bill


*Yeah, that counts as a gloat. They are coffee-table sized and ~6"
thick. Not sure if they are going to end up as flat work or turned ...
but, done well, either I'm going to have something my sons will fight
over when I'm gone or somebody else is going to give me a lot of money
for seizing an opportunity labeled "free firewood".


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