"billh" wrote in message
...
You may have a bad bearing somewhere. I don't have a Jet mini but to try
and pin it down I would remove the belt. Turn on the lathe and the motor
should run fairly quietly. If it rumbles then you probably have a bad
bearing in the motor.

Turn the unbelted spindle by hand and see if it turns freely and smoothly.
If not you probably have a bad spindle bearing.

Another trick is to use a stethoscope (or a piece of wood) to place on the
various bearing locations while the lathe is running. Put the stick on
the bearing location and then put your ear on the other end. Be careful
the bearing end doesn't slip onto moving parts! You can usually track
down the offending bearing quite quickly using this method. However, if
you replace the bad bearing then do yourself a favor and replace all the
bearings in that particular piece.

Bearings are lubricated for life so you didn't do anything wrong by not
lubing them. This doesn't apply to lathes that have bushings!

=========================
Another way to isolate the noise site is with a piece of garden hose or a
piece of automotive heater hose. Plug one ear and use the other to listen as
you move the hose to the various points you suspect of being faulty. A
stethoscope with the membrane removed is also a great tool.

Ken Moon
Webberville, TX