Maxprop wrote:
"Leo Lichtman" wrote in message
...

"Maxprop" wrote: (clip) Not sure which lathe you have, but my Jet 1442
will actually run a bit

slower than the last detent for the speed control (for the Reeves drive)
allows. I simply retract the pin and set the lathe a bit below that
detent. I checked the speed with an optical tach and found it runs at
roughly 280 rpm--much better than the 400 the bottom detent allows. This
of course begs the question as to whether this is hard on the Reeves
drive, or if it is an acceptable practice. No one at the Jet
distribution center had the slightest idea. But it works, and I'll
probably continue to use this method until I either damage the drive or
learn from an authority that it's deleterious. (clip)

^^^^^^^^^^^^^^^^^^^^^^^
I did something similar with my Jet 1236. I actually drilled an extra
hole so I could pull the lever down and lock it. I don't think it can do
any harm to run it that way. If anything is going to suffer, it will be
the belt, from running way up on the edges of the driven pulley. Belts
are easy to replace. When you do replace a belt, eventually, I recommend
the linked belts. They run with less vibration, and the length can be
adjusted in 1/2" increments, which may allow you to further reduce the
speed. See whether the belt bottoms on the motor pulley before it reaches
the largest diameter on the spindle pulley. If it does, you can further
lower the minimum RPM by adding length to the belt.

If you keep a short length of link belting on hand, you can repair a
broken belt without replacing the whole thing. Usually, a broken belt
results from a stall, which causes the motor pulley to spin on one spot,
burning the belt. So repairing by replacing a few links makes sense.


I'm using a link belt, Leo, and have been since last year when my original
belt began to show some rather ominous wear. The idea of replacing the belt
without pulling the pulleys was appealing, and the primary reason I chose to
use a link belt. But you are absolutely correct--it runs more smoothly with
less vibration, not to mention failing to show any significant wear after a
bit more than a year of use. I'm not sure if the link belt enables me to
use a slower speed than the former rubber belt, but it seems to work fine.

One additional point with Reeves drives: if the user remembers to slow the
drive down to the slowest speed detent before shutting the lathe down, the
next startup is far less stressful to the belt, link or otherwise. While I
don't know for sure, I can imagine that this might be true of lathes with
EVS drives as well.

If you mean electronic variable speed drives and if you are referring to
inverter drives for three phase motors, it doesn't matter where you
start, (so long as things are balanced) because they have a soft start
feature that slowly spins up to speed. I'm using a 3HP Teco inverter
fed by single phase 240vac, and running a 3 hp 3-phase motor on the
lathe. I can set any speed from about 40 to 1000 rpm on the spindle in
the current pulley setup, and as I turn larger items, this is a near
perfect range for me. (The lathe will swing 42" over the bed, about 37"
above the mount for the toolrest. Most of what I currently turn is 10
to 36" diameter, with length of 18 to 36" (tall when finished). As you
might imagine, it takes several seconds to go from zero to top speed,
but always starts slow and accelerates to speed. Unlike reeves drives
and other belt only systems, where the motor essentially goes from 0 to
full speed in a second or so, electronic speed controls can ramp up at a
rate determined by settings on the controller.
--Rick

Max