Hi Dale,

Good; at least you tried such.  I do wish you had a real closeup camera
and/or a web site to show the rounded end.  My guess is that it is diamond
wheel ground off and isn't anywhere near as round as a true sperical
ball.  Under ~ >15x magnifcation you visually might see "jerky steps" going
up to the domed rods end point top.  All those little steps likely
significantly impede smooth rotation where they make contact; as compared to
a
much more finely rounded ball.

This reminds years back of obtaining a unheat treated tool steel drill rod
shank/blank.  Boy, was that rod so visually shiny!  Under magnification,
the surface was so badly spirally groove marked from the lathe tool, it
was completely unuseable in a cross rod pivot test, and yielded the
shortest time for free oscillation time duration of any material I had.

I "presume" your domed rod end is making contact on a flat surface.

If you're game; just for fun, you might also sometime try a true crossed (3
rods) rod pivot on your (presumed) experimental "test" Lehman....it can
work almost frictionless very well....but they do have a obvious tendency to
"slip" or "walk" horizontally and vertically (or, at any angle); so you will
probably have to have alotof setup patience with adjustments.  All of which
is why......the 2 rods and a ball is used; it totally eliminates all the
otherwise pesky vertical slip/walk problem on a Lehman, but gets quite
decent results.

Take care, Meredith





On Mon, Jun 16, 2008 at 8:57 PM, Dale Hardy  wrote:

>  Hi Meredith,
> omitted to mention those 'capstan' rods also have a 'domed' end which has
> been used successfully as a pivot point on the arm of a lehman
> Dale
>
Hi Dale,
 
Good; at least you tried such.  I do wish you had a real closeup camera and/or a web site to show the rounded end.  My guess is that it is diamond
wheel ground off and isn't anywhere near as round as a true sperical ball.  Under ~ >15x magnifcation you visually might see "jerky steps" going
up to the domed rods end point top.  All those little steps likely significantly impede smooth rotation where they make contact; as compared to a
much more finely rounded ball.
 
This reminds years back of obtaining a unheat treated tool steel drill rod shank/blank.  Boy, was that rod so visually shiny!  Under magnification,
the surface was so badly spirally groove marked from the lathe tool, it was completely unuseable in a cross rod pivot test, and yielded the
shortest time for free oscillation time duration of any material I had.
 
I "presume" your domed rod end is making contact on a flat surface.
 



If you're game; just for fun, you might also sometime try a true crossed (3 rods) rod pivot on your (presumed) experimental "test" Lehman....it can
work almost frictionless very well....but they do have a obvious tendency to "slip" or "walk" horizontally and vertically (or, at any angle); so you will

probably have to have alotof setup patience with adjustments.  All of which is why......the 2 rods and a ball is used; it totally eliminates all the 
otherwise pesky vertical slip/walk problem on a Lehman, but gets quite decent results.

 
Take care, Meredith 
 
 
 
     


On Mon, Jun 16, 2008 at 8:57 PM, Dale Hardy <photon1@...........> wrote:



Hi Meredith,
omitted to mention those 'capstan' rods also have a 'domed' end which has been used successfully as a pivot point on the arm of a lehman
Dale