Thanks Chris and Meredith This is very helpful...
Bryan 




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

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

Hi Bryan,

       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. 
       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.
       You can also buy carbide spotting drills, center drills and various 
router and milling bits, but these are all likely to be more expensive. 
       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. 
       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. 
       Meredith has tried novel forms of these out with considerable success. 
My congratulations to him on his patience, dedication and skill! 

       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.   
       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!   

       Regards,

       Chris Chapman

 

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



Meredith Lamb,

Could you post pictures of the rod hinge/suspensions "your setup"

This sounds like somthing I would like to try.




Hi Bryan,



       You can get 1/8" tungsten carbide d=
rills (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 tun=
gsten carbide drills with an 1/8" shank for a bit under $4.50. I have search=
ed several US websites for these, but the only one that I found was digikey=20=
and they wanted $7.55 each! The overall length is 1.5" and the shank is 0.9"=
 long.

       You can also buy carbide spotting d=
rills, center drills and various router and milling bits, but these are all=20=
likely to be more expensive.=20

       You can also try out round 'tool st=
eel', but I would advise putting a drop of clock oil on the contact point an=
d 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 'stai=
nless' because they oxidise very readily, giving a protective surface film.=20=
They don't like chlorides, bromides, iodides or fluorides - and this include=
s 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 t=
he beam. If you do it the other way around, you may well have to completely=20=
reset the centring and period every time you reassemble / adjust the suspens=
ion. I have the mass offset mounted on the beam with the C of G underneath,=20=
to provide vertical stability and keep the end bearing rod horizontal. Jan M=
arshall uses this type of suspension See http://myweb.cableone.net/jandmarsh=
all/=20

       The wire figure of 8 suspensions th=
at I have tried were made from 8 thou dia nickel plated mandolin strings, bo=
ught from a music shop. These are piano wire, but are reasonably rust resist=
ant. See http://www.daddario.com/ The 8 thou piano wire has an 'ultimate str=
ength' of about 16.5 lbs max. The design working stress might be from 1/4 do=
wn to 1/20 of this, depending on the application. They are a bit more diffic=
ult to set up and adjust than a crossed cylinder and you can only bend the w=
ire once.=20

       Meredith has tried novel forms of t=
hese out with considerable success. My congratulations to him on his patienc=
e, dedication and skill!=20



       My ball on a flat suspensions were=20=
5mm stainless steel balls on a small diamond polished triangular carbide too=
l bits for a lathe. I mounted the ball on the vertical support and the flat=20=
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.=20=
I haven't tried these, but I would expect them to perform as well as the sta=
inless steel balls.   

       Meredith also tried out cleaned up=20=
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=20=
seemed quite enthusiastic about these till the tried out the figure of 8 wir=
e and the crossed cylinder suspensions!   



       Regards,



       Chris Chapman



=20