PSN-L Email List Message

Subject: Re: Mystery scavenger seismometer part and pivot systems
From: Charles Patton charles.r.patton@........
Date: Tue, 09 Sep 2008 21:36:32 -0700

It might make a good crossed wire roll pivot - if it has about three 
brothers.  Crossed wire/band pivots are similar to a Rollamite except 
with space between the rolls so they're not running in contact. In 
previous Brett Nordgren tests these types of pivots had the lowest 

Brett, Chris Chapman and I are putting the finishing touches on a web 
site page with exact formulas in spreadsheet form for several pivots so 
amateurs can experiment with more insight into what is happening with a 
given geometry, i.e., finding the locus for the pivot along with some 
practical comments about their use.

Formulas/spreadsheets for:
+ Crossed wire/band rolls (such as separated Rollamite cylinders)
+ Crossed wire/band suspensions (such as used in LIGO vibration 
isolation systems)
+ ball on plate (the typical pivot of choice for many Lehmans) (a bit of 
advance warning -- this is one of the worst)
+ plate on ball (much better than ball on plate, and same complexity of 

Charles Patton

meredith lamb wrote:
> Just for fun, I put this up on a web page.  What it is in normal use is 
> apparent, but the real scavenger
> in you question is; what do you think it could be used for in a 
> seismometer?  Yes; its a bit "outside the box"
> of what a great majority of home seismometer builders have done/tried/or 
> actually use.  I doubt the mystery
> description/use will take very long for someone to give the right answer.
> Take care, Meredith

Public Seismic Network Mailing List (PSN-L)

[ Top ] [ Back ] [ Home Page ]