A novel offset pivot S-G
This is a novel offset pivot test inspired by a accident where it worked in a offset fashion much like below; while the original intent was to set in up in a standard upright gravity pendulum fashion. The pendulum still hangs down but is offset ~ 5 degrees. The unit is noteably easily set in motion by environmental air currents if unshielded from such. The tilt reaction is also noteably quite sensitive.
Although the ruby balls and carbide flat pivot in itself isn't unique; the initial oscillation duration time test (for crudely testing pivot friction) with a 1/4" mass offset was 3 hours and 30 minutes. For whatever reason, this duration time seems to be the longest I've yet seen in any ball/flat pivot and that alone makes it more than alittle interesting.
The first initial carbide edge pivot lasted almost 3 hours, and its pivot contact was only on two portions of the hard drive surface over the top plate hole. This entire web page has been redone for clarity from that first published on July 4th 2008.
The latest model (not shown), is one where two flat carbide inserts were glued to the boom flat and two same size ruby balls were glued to the frame. In other words the flats were oscillating atop the fixed balls. The oscillaton time was almost precisely the same; 3 hours and 29 minutes.
Here 1/8" mirror finish ruby balls have replaced the previous carbide edge pivot. Underneath on the second photo, I put a near mirror finish carbide flat underneath the balls.
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The photo above is a clear view of the ball pivots.
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The photo above is of the pivot atop a S-G test stand.
One could potentially use just a large washer instead of the aluminum shown. The balls are about a 1/4" away from the boom/threaded rod. The threaded rod is the "boom" which connects to a 2 pound mass about 8 inches below. At a horizontal inclination rest the boom is tilted about ~5 degrees. When one inclines the S-G frame in the sensing direction, the alignment with the frame is apparent. Here the sensing direction is to the left and right as viewed. The rectangular plate on the counter underneath one leg of the frame is 1/8" thick. With regular adjustment screws the plate wouldn't be necessary.
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The sensitivity of this unit seems to be such that it might even be possible to even use a velocity coil and magnet sensor...besides the usual higher displacement sensors....or even a combination of both.
Being as the mass is offset from a more normal pivot setup; it maybe even possible to add on a pivot area metal extension, and a adjustable vertical spring to create a vertical sensing unit.