From: tchannel1@............

Date: Sun, 2 Mar 2008 14:15:47 -0700

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. TedHello,I think I am done playing with this = (propeller=20 shape) Nearly Balanced Pendulum http://www.p= hy.mtu.edu/~suits/PH3110/pendulums.htmlI 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