NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Leap seconds at Big Ben.
From: Richard M Pisko
Date: 2009 Jan 04, 00:27 -0700
From: Richard M Pisko
Date: 2009 Jan 04, 00:27 -0700
On Thu, 01 Jan 2009 12:32:55 -0700,wrote: > On the home-made regulator clock whose picture I include as an > attachment, I use increments of 100 milligrams and can achieve a rate of > two or three seconds a month, but as the brass-compensated Invar > pendulum rod is not (yet) correctly compensated, the rate changes with > the season. Where is the pendulum weight fastened to the invar rod; and how? I was wondering . . . if the rod were to have male threads at a certain pitch, say 20 threads per inch on a 1/2 inch diameter rod, and the brass cylinder were to have female threads of say 3/4 by 20 tpi, there is room for a short sleeve about 1/8 inch thick to hold the rod and pendulum weight together. The sleeve would be threaded inside and out at the same 20 tpi to fit the rod and weight, and a couple of notches at the lower end would allow the sleeve to be screwed up or down by a hollow shaft screwdriver. The relative location of the brass weight and the rod would remain the same, but the amount of temperature compensation would change, I think. For example, as the sleeve is screwed downward, the top end of the brass weight would remain in the same position relative to the rod initially, but would move upward more as the temperature increases. The change in position of the sleeve (lowered) would have to be compensated by adding a weight in your tray, I believe, or by screwing the brass weight upward a bit on the sleeve and rod. Is this what you did? If the Invar rod length were actually invariable in a moderate temperature range, I think placing the sleeve in the mid point of the brass cylinder would be a good start experimentally, but where would theory suggest? What a fascinating assortment of projects you have. -- Richard . . . Using Opera 9.2.4 after the "Dog" died --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---