In a message dated 2008/07/15, DSaum@............ writes:

> I bought some carbide rods (1/8" x 1.5") from eBay that appeared to be 
> polished, but under 30x magnification they were quite rough. But I was able to 
> get a nice mirror polish on carbide rods with this set of diamond paste polish 
> from eBay
> http://cgi.ebay.com/12-pcs-5gram-Diamond-polishing-lapping-paste-compound_W0Q
> QitemZ180262758807QQcmdZ
> 
> I started with the 10 micron polish and worked down to the 0.5 micron 
> polish.
> 
> Polish was applied to a paper towel, and a hand drill was used to rotate the 
> rod against the towel for about 30 seconds for each polish.  A black residue 
> gives an
> indication that the polish is actually working.

Hi Dave,

       This will NOT produce the optimum smoothness. A flexible backing 
material just follows the existing wavy contours. You need to use copper laps and 
work along the length to remove the ridges often left by machining. Bend about 1
/2" length of 0.040 thou thick U of copper around a mandrel / drill / the 
carbide rod and use the U against the carbide rod with diamond paste + oil.

> I plan to use an 1/8"sapphire ball against two of the rods
> for an improved Lehman pivot.

       I suggest that you either use crossed carbide rods with the vertical 
rod on the support post, or that you put the ball on the vertical support post. 
A ball rolling on a plane is considerably inferior to a plane rolling on a 
ball. A two rods rolling on a ball are likely to have a higher frictional loss 
than crossed rods.

       Regards,

       Chris Chapman   
In a me=
ssage dated 2008/07/15, DSaum@............ writes:



I bought some carbide rods (1/8=
" x 1.5") from eBay that appeared to be polished, but under 30x magnificatio=
n they were quite rough. But I was able to get a nice mirror polish on carbi=
de rods with this set of diamond paste polish from eBay

http://cgi.ebay.com/12-pcs-5gram-Diamond-polishing-lapping-paste-compound_W0=
QQitemZ180262758807QQcmdZ



I started with the 10 micron polish and worked down to the 0.5 micron polish=
..



Polish was applied to a paper towel, and a hand drill was used to rotate the=
 rod against the towel for about 30 seconds for each polish.  A black r=
esidue gives an

indication that the polish is actually working.




Hi Dave,



       This will NOT produce the optimum smoot=
hness. A flexible backing material just follows the existing wavy contours.=20=
You need to use copper laps and work along the length to remove the ridges o=
ften left by machining. Bend about 1/2" length of 0.040 thou thick U of copp=
er around a mandrel / drill / the carbide rod and use the U against the carb=
ide rod with diamond paste + oil.



I plan to use an 1/8"sapphire b=
all against two of the rods

for an improved Lehman pivot.




       I suggest that you either use crossed c=
arbide rods with the vertical rod on the support post, or that you put the b=
all on the vertical support post. A ball rolling on a plane is considerably=20=
inferior to a plane rolling on a ball. A two rods rolling on a ball are like=
ly to have a higher frictional loss than crossed rods.



       Regards,



       Chris Chapman