[TheForge] Re: File Making

[Mike Spencer]

Dave Smucker wrote:

> ...the very best roller bearings are case harden, very deep case, as
> much as 0.060 deep and the core is a very tough alloy steel similar
> to 4120.  (Timken, which in my experience with very large bearings
> are the world's best.)  Same is true for high performance large gear
> sets.

So, Dave, is that carbon case?  Or nitriding?

When I worked in a wire mill (Michelin) the capstan drums over which
the wire passed in various continuous-process treatments had to have
absolutely minimal wear since if one drum's diameter differed from
another in the train or differed from one point to another along its
surface, the wire speed wouldn't be consistent and there would be
breaks, sags or snarls. So the the drums were machined to matching
size, heated for hours (days? I forget) in a nitrogen atmosphere and
then, if needed, finish ground to match with an optical comparator.
They still didn't last forever but, according to the shop scuttlebut,
they wouldn't have lasted a day without that treatment.


- Mike

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                                           /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^