<VV> Nitride (TuffTride) crank ID

djtcz at comcast.net djtcz at comcast.net
Sat May 9 06:50:33 EDT 2009

snipped and bottom posted 

----- Original Message ----- 
From: Chris & Bill Strickland < lechevrier at earthlink.net > 
Subject: Re: <VV> Nitride Crank ID 

>The crank did not have the infinity symbol on the gear end like most hardened cranks do. 

That is why I was asking for pictures -- here, Mark is describing the 
mark as an infinity character -- maybe similar, but different than an 
ampersand.  I have a crank with what appears to be a partial mark that 
doesn't look like an ampersand to me, but does look like part of an 
infinity character.  Which is it? 

This particular crank also has a sort of squared "O" with a line through 
it stamped rather deeply.  It is a 145 inch crank. 

Can't really help with Marks alternate testing other than recommend 
taking it to a heat treater or metalugist, or maybe a university with a 
Metalurgy Dept where they can test the hardness (probably want to do 
this on the throws rather than the journals. 

TuffTride is HARD.  Over Rockwell 60 C, like ball bearing races and balls. 

A metal file does not cut it at all. Even a nice new sharp US made file Just slides right over the surface.  Unlike, even a grade 8 bolt (rockwell 40 something C).  I use a part of the file near the handle because it is still sharp there, and the test dulls the file. 

But if the crank has been ground undersize, the journals' thin layer of hardness is gone, even though the cheeks etc will test hard.  

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