[AT] OT - How a steam locomotive gets built in 1935

[Roy Morgan]

On Nov 18, 2012, at 8:49 AM, Don Bowen wrote:
> ...  It was a real job staying one class ahead of
> some very sharp machinists.

I heard a story about machinists' training in the Leica Camera works.   
They had to take a precision polished cube of steel and turn it into a  
perfect, polished sphere of the *same* dimension.

I can only guess what it takes to do that.  But I have a good idea  
what it's like to use a Leica.  Nothing else like it.

Where I used to work (NIST - formerly NBS), the metrology folks had  
set up one of the word's most accurate coordinate measuring machines  
(CMM), and made it even more accurate.  The thing does calibrations on  
national and international standards of length up to a meter in  
length.  These are bars made of special alloy with polished spheres on  
each end, the center of which defines the measured length point.  The  
distances are measured with lasers, with the wavelength of light (or  
fraction thereof) being the measuring standard.

The moving parts of the CMM run on ways made of polished granite that  
were "lubricated" with a three atom thick layer of dry nitrogen.  The  
room temperature was held to about one hundredth degree C for  
stability.  If the dry nitrogen failed and the ways touched each  
other, it would take a month and temporary duty experts from Germany  
to set it right again.

But great credit is due to those locomotive folks.  Their machines did  
run at up to 80 miles per hour for years, and a couple of them still  
run!

Roy


Roy Morgan
k1lky at earthlink.net
K1LKY Since 1958 - Keep 'em Glowing!