I have been reading this thread for quite some time and think that some
of the replies are very good and explain it pretty well, but I have been
very disappointed from the scientific point of view.  That is, regarding
the basic question, "How hot is the motor temperature-wise?"

Has anyone heard of a very simple scientific instrument called a
thermometer, that was invented way back in the 1500's?  Ever heard of
early scientists such as Galileo, who invented a rudimentary water
thermometer?  Or Santorio Santorio, who put a numerical scale on the
instrument?   How about Daniel Gabriel Fahrenheit, a German physicist,
who invented an alcohol thermometer in 1709, and the mercury thermometer
in 1714?  Today many people around the world use thermometers with the
Fahrenheit scale.  Or how about the great Swedish astronomer Anders
Celsius, who invented the Celsius or centigrade scale, which is used all
over the world.  Or, for the UK people, there is the Scotsman Lord Will-
iam Thomson Kelvin, who invented the Kelvin scale in 1848 which measures
the extremes of hot and cold.

I think you can buy a very cheap digital thermometer over in the UK for
about £5, or here in the U.S. for less than $10.00.  They work great and
they will settle once and for all the question "Is the motor running too
hot?"  Quit using the finger-and-brain method, which only tells you to
pull your finger off something too cold or hot and does not give you an
accurate temperature.

So, my proposal is: do it the scientific way and actually measure the
temperature of the motor under varying conditions from no-load to normal
operation and a stress-overload test.  For each test, take readings every
fifteen minutes of the following points and put them on a graph or chart:
1. ambient temperature of the room, 2. both bearings, 3. top of the motor,
4. bottom of the motor, 5. a couple of places on the windings that you
can reach, 6. the bottom of the piano directly over the motor, 7. several
places around the bottom of the piano, 8. the top of the piano.

If you run each test for several hours, there will be a point at which
the temperature does not change.  There you can stop, as the motor will
not get any hotter.

It would be nice if several people around the world did the same test on
their piano motor, so that the data could be compared.  Then we would
know the typical temperature of old, original windings and of new wind-
ings under varying conditions.  Then we would settle the argument once
and for all "Is the motor really running too hot?"

Larry Norman,
from the Blue Ridge Mountains of Virginia
(I saw a robin yesterday, the daffodils are starting to come out, and it
is warming up. I think spring is coming and the parkway and Virginia will
be beautiful very soon!)