Hello,

I think I am done playing with this (propeller shape) Nearly Balanced =
Pendulum http://www.phy.mtu.edu/~suits/PH3110/pendulums.html

I made five total.   The first one did not work at all.  This was =
several months ago when I first read the above article.   I just threw =
it together, using a stick and nails, so I should not have been =
surprised.

Recently I tried it again, this time taking a little more time.   This =
one did work, but not too well.   I tried again, and again and each time =
it did work better.   By working better I mean I could get longer =
periods, but never stability.

My latest attempt, as I mentioned was successful, and with some effort I =
could get 20 seconds, but if-y stability.    Our friend Chris, wrote =
that I could not get the stability at the longer periods if the pivot =
was not adequate.    He was correct.

Here are the details from today's Nearly Balanced Pendulum.

The pivot is roller on roller using drill bit shanks.  Not the best, but =
the best so far.
The Pendulum is 72" long and a pivot at 36".  At that point it look like =
a (+)  The length of the pivot is about 4" going Left to Right, and on =
each side it rocks on another short piece of drill bit.  I used a tripod =
as a base for the pivot.
The Pendulum is made of electrical conduit tubing. A little more =
straight than a wooden dowel.  Coming out of each end is a 1/4 20 =
threaded rod 6" long.  On these two rods are nuts, to balance it =
vertically, shifting more mass to one end and doing so, to shorten or =
extend the period.
I found it necessary to add a different smaller threaded rod at the =
bottom or top, which then formed a (T).    This rod moving Left or Right =
balances the Pendulum vertically.  Without it, the Pendulum would not =
come to rest vertical, but more like 2:00 o'clock.

I had no trouble obtaining 53 seconds +, I think I could get 60.   And =
the Pendulum is stable and when moved returns to vertical.

Just wanted to share.
Ted











Hello,
 
I think I am done playing with this =
(propeller=20
shape) Nearly Balanced Pendulum http://www.p=
hy.mtu.edu/~suits/PH3110/pendulums.html
 
I made five total.   The =
first one did=20
not work at all.  This was several months ago when I first read the =
above=20
article.   I just threw it together, using a stick and nails, =
so I=20
should not have been surprised.
 
Recently I tried it again, this time =
taking a=20
little more time.   This one did work, but not too =
well.   I=20
tried again, and again and each time it did work better.   By =
working=20
better I mean I could get longer periods, but never =
stability.
 
My latest attempt, as I mentioned was =
successful,=20
and with some effort I could get 20 seconds, but if-y=20
stability.    Our friend Chris, wrote that I could =
not get=20
the stability at the longer periods if the pivot was not=20
adequate.    He was correct.
 
Here are the details from today's =
Nearly Balanced=20
Pendulum.
 
The pivot is roller on roller using =
drill bit=20
shanks.  Not the best, but the best so far.
The Pendulum is 72" long and a pivot at =
36". =20
At that point it look like a (+)  The length of the pivot is about =
4" going=20
Left to Right, and on each side it rocks on another short piece of drill =

bit.  I used a tripod as a base for the pivot.
The Pendulum is made of electrical =
conduit=20
tubing. A little more straight than a wooden dowel.  Coming =
out of=20
each end is a 1/4 20 threaded rod 6" long.  On these two rods are =
nuts, to=20
balance it vertically, shifting more mass to one end and =
doing=20
so, to shorten or extend the period.
I found it necessary to add a different =
smaller=20
threaded rod at the bottom or top, which then formed a =
(T).   =20
This rod moving Left or Right balances the Pendulum vertically.  =
Without=20
it, the Pendulum would not come to rest vertical, but more like 2:00=20
o'clock.
 
I had no trouble obtaining 53 seconds =
+, I think I=20
could get 60.   And the Pendulum is stable and when moved =
returns to=20
vertical.
 
Just wanted to share.
Ted