---------- Forwarded message ----------
From: meredith lamb 
Date: Sep 17, 2005 1:56 PM
Subject: Re: [Fwd: additional hurricane studies]
To: "ChrisAtUpw@......." 

Hi Chris,
 Thanks for the information!!! It is a interesting approach for a hanging=
=20
pendulum (for us amateurs; they could also be called "S-G's" of course. It=
=20
would seem to allow for a very tight capactive sensor spacing without most=
=20
of the non-sensing possible sideways spurious motion (assuming a rigid boom=
)=20
as opposed to using like acouple strips of flexible thin aluminum, brass=20
etc., to suspend a boom/mass of most current models I've seen. Of course,=
=20
such a hinge could be fairly easily adopted for two wire pickup coils or=20
with more difficulty for using 3 wire Hall sensors also.=20
 Of course aside from the exotic approache/s discussed, and for the majorit=
y=20
of us, one could consider the ball bearing approach, where the top of the=
=20
boom has a "T" section, and two ball bearings are affixed underneath and on=
=20
the ends of the extension "arms" of the "T" boom top framed used, and in=20
contact with acouple plain and level and nearby adjacent flat surfaces.=20
Aside from the electrical contact problem, one could run a wire, or=20
insulated wires from atop the boom via flexible small diameter gauge wire/s=
=20
in spring like coil shapes for minimum physical influence. It would=20
certainly alleviate alot of construction detail hassles via thin flat metal=
=20
strips of older hinge designs. From what I hear, the ball bearing approach=
=20
with horizontals works quite well....so....why not with a hanging pendulum?=
=20
Here, the weight of the boom/mass can be quite abit larger of course. The=
=20
boom/mass would get thrown off with a strong local quake I suppose, but mos=
t=20
instruments would also be useless in the kind of event circumstance also.=
=20
 Another approach could be intrinsically with also two ball bearings on a=
=20
frame which rests atop a single larger center support, but where it is in a=
=20
"U" shape over and separated from the support (with the ends of the "U"=20
downward). Now....one would have two "booms", with which to entertain using=
=20
sensors and or dampening, and/or=20
feedback to one side or the other. One could still call it a "hanging gate"=
,=20
but with the vertical (hanging) slant of course. For example: Acouple glued=
=20
end to end bricks (the center support), should give enough height for a=20
natural oscillating period of one second, but with a very sensitive sensor=
=20
one should pick up long period waves easily...not physically pretty, but it=
=20
could work well I'd think. Round brass/copper and compression "T" fittings=
=20
come to mind here. The two ball bearings would likely have to be centered o=
n=20
the diameter/width on the cross support for correct vertical balance, but=
=20
their is likely other mechanical ways of means of correcting this, if its=
=20
shown to be a problem.=20
 Interesting and fun stuff...it kind of makes one want to run out and start=
=20
building doesn't it....
 Take care, Meredith Lamb=20

 On 9/16/05, ChrisAtUpw@.......  wrote:=20
>=20
> Was particularly interested in the pendulum hinge; but, the photos don't=
=20
> seem=20
> to totally show exactly how they maintain position or their contact shape=
=20
> or the adjacent "supports" they rest on.=20
>=20
> Hi Meredith,=20
>=20
> The suspension is vertical sapphire phonograph needles on sapphire plates=
..=20
> He has had problems with the tips digging in (why am I not surprised?), s=
o=20
> don't try copying it. I don't know why he hasn't used sapphire spheres. T=
hey=20
> are available.=20
>=20
> I suggested tungsten carbide crossed cylinders, but he wasn't very=20
> receptive to the idea. You just buy drill bits and cut off the shank end!=
=20
> Latest idea is to use tungsten carbide spheres from roller ball pens on=
=20
> martensitic stainless steel. I think that he is heading for trouble. The=
=20
> 'balls' are far too tiny and are not actually spherical, but he wants it =
to=20
> be *'cheap'*. Stainless steel is only stainless because it oxidises=20
> immediately to give a protective film. Stressing the surface is likely to=
=20
> increase the oxide thickness and give an insulating layer, which is exact=
ly=20
> what he doesn't want.=20
>=20
> My philosophy is that it must work and work well. You sort out the cost=
=20
> later.=20
>=20
> Regards,=20
>=20
> Chris


---------- Forwarded message ----------
From: meredith lamb <paleoartifact@.........>
Date: Sep =
17, 2005 1:56 PM

Subject: Re: [Fwd: additional hurricane studies]
To: "ChrisAtUpw@......." <ChrisAtUpw@.......>


Hi Chris,
 
Thanks for the information!!!  It is a interesting approach for a=
 hanging pendulum (for us amateurs; they could also be called "S-G's&q=
uot; of course.  It would seem to allow for a very tight capactive sen=
sor spacing without most of the non-sensing possible sideways spurious moti=
on (assuming a rigid boom) as opposed to using like acouple strips of flexi=
ble thin aluminum, brass etc., to suspend a boom/mass of most current model=
s I've seen.  Of course, such a hinge could be fairly easily adopted f=
or two wire pickup coils or with more difficulty for using 3 wire Hall sens=
ors also.=20

 
Of course aside from the exotic approache/s discussed, and for the maj=
ority of us, one could consider the ball bearing approach, where the top of=
 the boom has a "T" section, and two ball bearings are affixed un=
derneath and on the ends of the extension "arms" of the "T&q=
uot; boom top framed used, and in contact with acouple plain and level and =
nearby adjacent flat surfaces.  Aside from the electrical contact prob=
lem, one could run a wire, or insulated wires from atop the boom via flexib=
le small diameter gauge wire/s in spring like coil shapes for minimum physi=
cal influence.  It would certainly alleviate alot of construction deta=
il hassles via thin flat metal strips of older hinge designs.  From wh=
at I hear, the ball bearing approach with horizontals works quite well....s=
o....why not with a hanging pendulum?  Here, the weight of the bo=
om/mass can be quite abit larger of course.  The boom/mass would get t=
hrown off with a strong local quake I suppose, but most instruments would a=
lso be useless in the kind of event circumstance also.=20

 
Another approach could be intrinsically with also two ball bearings on=
 a frame which rests atop a single larger center support, but where it is i=
n a "U" shape over and separated from the support (with the ends =
of the "U" downward).  Now....one would have two "booms=
", with which to entertain using sensors and or dampening, and/or=20

feedback to one side or the other.  One could still call it a &qu=
ot;hanging gate", but with the vertical (hanging) slant of course.&nbs=
p; For example: Acouple glued end to end bricks (the center support), =
should give enough height for a natural oscillating period of one seco=
nd, but with a very sensitive sensor one should pick up long period wa=
ves easily...not physically pretty, but it could work well I'd think. =
 Round brass/copper and compression "T" fittings come to mind her=
e.  The two ball bearings would likely have to be centered on the diam=
eter/width on the cross support for correct vertical balance, but their is =
likely other mechanical ways of means of correcting this, if its shown to b=
e a problem.=20

 
Interesting and fun stuff...it kind of makes one want to run out and s=
tart building doesn't it....
 
Take care, Meredith Lamb  

 

On 9/16/05, =
ChrisAtUpw@....... <
ChrisAtUpw@.......> wrote:=20
<=
font size=3D"2">Was particularly interested in the pendulum hinge; bu=
t, the photos don't seem=20

to totally show exactly how they maintain position or their contact sha=
pe or the adjacent "supports" they rest on. 

Hi Mer=
edith, 

      The suspension is vertic=
al sapphire phonograph needles on sapphire plates. He has had problems with=
 the tips digging in (why am I not surprised?), so don't try copying it. I =
don't know why he hasn't used sapphire spheres. They are available.=20


      I suggested tungsten carbide cr=
ossed cylinders, but he wasn't very receptive to the idea. You just buy dri=
ll bits and cut off the shank end! Latest idea is to use tungsten carbide s=
pheres from roller ball pens on martensitic stainless steel. I think that h=
e is heading for trouble. The 'balls' are far too tiny and are not actually=
 spherical, but he wants it to be=20
'cheap'. Stainless steel is only stainless because it oxidises immed=
iately to give a protective film. Stressing the surface is likely to increa=
se the oxide thickness and give an insulating layer, which is exactly what =
he doesn't want.=20


      My philosophy is that it must w=
ork and work well. You sort out the cost later. 

   &=
nbsp;  Regards, 

      Chris=