PSN-L Email List Message

Subject: Re: Crossed rod hinge/suspensions v/s ball bearings hinge/suspensions
From: "KATHRYN ROBERTS" KROBERTS23@...............
Date: Wed, 26 Oct 2005 13:57:16 -0400


Hi, i am the one who proposed the double shim hinge for a horizonal =
sesimometer.  However the string method would seem to have less =
torsional resistance than the double vertigal shim.  Will the =
string/filamentsupport the horizontal pendulum 'boom' ? (or will boom =
weight allow the vertical vector)gravity allow the boom to dop far =
enough to significantly the angle the once horivontal string/filament =
enough to increase the angle of the mast end of the pendulum and affect =
it's torque? i don't know if increasing the angle will adversely =
effect/increase the torque needed to allow easy horizontal motion to the =
pendulum or if the arrangement will decrease the needed torque forces to =
swing the pendulum. i feel the wire/string/filament will increase the =
needed torque to move the pendulum, but this a gut level (no pun =
intended) and my track record of being about right about such feelings =
run less that 50%.                i know my written descriptions are =
cryptic at best and probably  enigatic at best. i have no way to scan =
drawings or post pictures on the net. If someone would send me a snail =
mail address and would be willing to scan my hand drawn plans (i did =
take mechanical drawing at school in the middle of the last century) and =
i would happy send my hand drawn to that person. As a way of =
introduction, i am a general practiticaner   and my name shoud be in the =
'phone book as 'geoffrey roberts, DO. i'm in Crystal River, FL   My work =
number is 352-795-2283 or 352-795-5544 or
795-2664, which will be an answering mach. Just leave a number and i'll =
return your call.
some will answer dr's office or 'may i help you? i mention my only job =
to attempt to people at ease about giving me their address. Hopefully =
someone will have a post office box that would  help perserve their =
idenity.    <>     i am enjoying this post. But i'm fairly busy  and =
don't have time to build and test  each different seisomos. Because of =
the time factor i have decided to start with horizontal pendulums. =
Thanks for listening. geoffrey roberts, 1035 N Stoney Point  <>  Crystal =
River Fl   <> USA. If you're still concerned, you take my 16 and 14 year =
old boys  as a hostage. i do think you should O'Henry's short story =
entitled "The Ransom of red Chief." before you agree to these =
conditions.  Thank you, Dr. geoffrey roberts, Crystal River 34429 P.S.,  =
 After this e-mail, please forget that i'm a doctor and send messages to =
'just geoff.' gr
   ---- Original Message -----                        =20
  From: ChrisAtUpw@..........
  To: psn-l@.................
  Sent: Sunday, October 23, 2005 11:19 PM
  Subject: Re: Crossed rod hinge/suspensions v/s ball bearings =
hinge/suspensions


  In a message dated 24/10/05, 1goss@........... writes:=20


    Meredith Lamb,=20
    Could you post pictures of the rod hinge/suspensions "your setup"=20
    This sounds like somthing I would like to try.


  Hi Bryan,=20

        You can get 1/8" tungsten carbide drills (ordinary type) from =
www.smallparts.com for $4.20 each. The one that I have is about 2 1/4" =
long and half of that is usable shank.=20
        I buy the printed circuit board tungsten carbide drills with an =
1/8" shank for a bit under $4.50. I have searched several US websites =
for these, but the only one that I found was digikey and they wanted =
$7.55 each! The overall length is 1.5" and the shank is 0.9" long.=20
        You can also buy carbide spotting drills, center drills and =
various router and milling bits, but these are all likely to be more =
expensive.=20
        You can also try out round 'tool steel', but I would advise =
putting a drop of clock oil on the contact point and a paper dust screen =
around it. The oil has an 'extreme pressure' additive, which prevents =
metal to metal contact. Steel rolling on steel can give rust / corrosion =
on the contact point otherwise. Stainless steels are only 'stainless' =
because they oxidise very readily, giving a protective surface film. =
They don't like chlorides, bromides, iodides or fluorides - and this =
includes common salt and perspiration.=20
        On a Lehman, I mounted the vertical carbide rod on the support =
column and the mating horizontal on the end of the beam. If you do it =
the other way around, you may well have to completely reset the centring =
and period every time you reassemble / adjust the suspension. I have the =
mass offset mounted on the beam with the C of G underneath, to provide =
vertical stability and keep the end bearing rod horizontal. Jan Marshall =
uses this type of suspension See http://myweb.cableone.net/jandmarshall/ =

        The wire figure of 8 suspensions that I have tried were made =
from 8 thou dia nickel plated mandolin strings, bought from a music =
shop. These are piano wire, but are reasonably rust resistant. See =
http://www.daddario.com/ The 8 thou piano wire has an 'ultimate =
strength' of about 16.5 lbs max. The design working stress might be from =
1/4 down to 1/20 of this, depending on the application. They are a bit =
more difficult to set up and adjust than a crossed cylinder and you can =
only bend the wire once.=20
        Meredith has tried novel forms of these out with considerable =
success. My congratulations to him on his patience, dedication and =
skill!=20

        My ball on a flat suspensions were 5mm stainless steel balls on =
a small diamond polished triangular carbide tool bits for a lathe. I =
mounted the ball on the vertical support and the flat on the arm, again =
to fix the centre of rotation. I was fairly happy with the performance, =
since it seemed quite a bit better than a flex foil that I had been =
using. I note that www.smallparts.com do sell tungsten carbide balls. I =
haven't tried these, but I would expect them to perform as well as the =
stainless steel balls.   =20
        Meredith also tried out cleaned up BIC medium ball pen tips. =
These use 1 mm dia carbide balls nicely mounted in a brass holder, but =
they are not really suitable for heavy loads. Meredith seemed quite =
enthusiastic about these till the tried out the figure of 8 wire and the =
crossed cylinder suspensions!   =20

        Regards,=20

        Chris Chapman=20









Hi, i am the one who proposed the = double shim hinge=20 for a horizonal sesimometer.  However the string method would seem = to have=20 less torsional resistance than the double vertigal shim.  Will = the=20 string/filamentsupport the horizontal pendulum 'boom' ? (or will boom = weight=20 allow the vertical vector)gravity allow the boom to dop far enough to=20 significantly the angle the once horivontal string/filament enough to = increase=20 the angle of the mast end of the pendulum and affect it's torque? i = don't know=20 if increasing the angle will adversely effect/increase the torque needed = to allow easy horizontal motion to the pendulum or if the = arrangement will=20 decrease the needed torque forces to swing the pendulum. i feel the=20 wire/string/filament will increase the needed torque to move the = pendulum, but=20 this a gut level (no pun intended) and my track record of = being about=20 right about such feelings run less that 50%.   =20             i know = my written=20 descriptions are cryptic at best and probably  enigatic at best. i = have no=20 way to scan drawings or post pictures on the net. If someone would send = me a=20 snail mail address and would be willing to scan my hand drawn plans (i = did=20 take mechanical drawing at school in the middle of the last = century) and i=20 would happy send my hand drawn to that person. As a way of introduction, = i am a=20 general practiticaner   and my name shoud be in the 'phone = book as=20 'geoffrey roberts, DO. i'm in Crystal River, FL   My work = number is=20 352-795-2283 or 352-795-5544 or
795-2664, which will be an answering = mach. Just=20 leave a number and i'll return your call.
some will answer dr's office or 'may i = help you? i=20 mention my only job to attempt to people at ease about giving me = their=20 address. Hopefully someone will have a post office box that=20 would  help perserve their idenity.   =20 <>     i am enjoying this post. But i'm = fairly=20 busy  and don't have time to build and test  = each different=20 seisomos. Because of the time factor i have decided to start with = horizontal=20 pendulums. Thanks for listening. geoffrey roberts, 1035 N Stoney = Point =20 <>  Crystal River Fl   <> USA. If you're = still=20 concerned, you take my 16 and 14 year old boys  as a hostage. i do = think=20 you should O'Henry's short story entitled "The Ransom of red = Chief." before=20 you agree to these conditions.  Thank you, Dr. geoffrey roberts, = Crystal=20 River 34429 P.S.,   After this e-mail, please forget that i'm = a doctor=20 and send messages to 'just geoff.' gr
 ---- Original Message=20 = -----           &n= bsp;=20            
From:=20 ChrisAtUpw@.......
To: psn-l@..............
Sent: Sunday, October 23, 2005 = 11:19=20 PM
Subject: Re: Crossed rod=20 hinge/suspensions v/s ball bearings hinge/suspensions

In=20 a message dated 24/10/05, 1goss@........... writes: =

Meredith Lamb,
Could you post pictures of the rod=20 hinge/suspensions "your setup"
This sounds like somthing I would = like to=20 try.


Hi Bryan,=20

      You can get 1/8" tungsten = carbide=20 drills (ordinary type) from www.smallparts.com for $4.20 = each. The=20 one that I have is about 2 1/4" long and half of that is usable shank. =
      I buy the printed circuit = board=20 tungsten carbide drills with an 1/8" shank for a bit under $4.50. I = have=20 searched several US websites for these, but the only one that I found = was=20 digikey and they wanted $7.55 each! The overall length is 1.5" and the = shank=20 is 0.9" long.
      You can also buy = carbide=20 spotting drills, center drills and various router and milling bits, = but these=20 are all likely to be more expensive.=20
      You can also try out round = 'tool=20 steel', but I would advise putting a drop of clock oil on the contact = point=20 and a paper dust screen around it. The oil has an 'extreme pressure' = additive,=20 which prevents metal to metal contact. Steel rolling on steel can give = rust /=20 corrosion on the contact point otherwise. Stainless steels are only=20 'stainless' because they oxidise very readily, giving a protective = surface=20 film. They don't like chlorides, bromides, iodides or fluorides - and = this=20 includes common salt and perspiration.=20
      On a Lehman, I mounted the = vertical=20 carbide rod on the support column and the mating horizontal on the end = of the=20 beam. If you do it the other way around, you may well have to = completely reset=20 the centring and period every time you reassemble / adjust the = suspension. I=20 have the mass offset mounted on the beam with the C of G underneath, = to=20 provide vertical stability and keep the end bearing rod horizontal. = Jan=20 Marshall uses this type of suspension See=20 http://myweb.cableone.net/jandmarshall/=20
      The wire figure of 8 = suspensions that=20 I have tried were made from 8 thou dia nickel plated mandolin strings, = bought=20 from a music shop. These are piano wire, but are reasonably rust = resistant.=20 See http://www.daddario.com/ The 8 thou piano wire has an 'ultimate = strength'=20 of about 16.5 lbs max. The design working stress might be from 1/4 = down to=20 1/20 of this, depending on the application. They are a bit more = difficult to=20 set up and adjust than a crossed cylinder and you can only bend the = wire once.=20
      Meredith has tried novel forms = of=20 these out with considerable success. My congratulations to him on his=20 patience, dedication and skill! =

      My=20 ball on a flat suspensions were 5mm stainless steel balls on a small = diamond=20 polished triangular carbide tool bits for a lathe. I mounted the ball = on the=20 vertical support and the flat on the arm, again to fix the centre of = rotation.=20 I was fairly happy with the performance, since it seemed quite a bit = better=20 than a flex foil that I had been using. I note that www.smallparts.com = do sell=20 tungsten carbide balls. I haven't tried these, but I would expect them = to=20 perform as well as the stainless steel balls.   =20
      Meredith also tried out = cleaned up BIC=20 medium ball pen tips. These use 1 mm dia carbide balls nicely mounted = in a=20 brass holder, but they are not really suitable for heavy loads. = Meredith=20 seemed quite enthusiastic about these till the tried out the figure of = 8 wire=20 and the crossed cylinder suspensions!   =20

      Regards,=20

      Chris Chapman=20



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