Somewhere in that pop mechanics edition is a segment on Thermite welding 
of RR tracks
Reference back to a conversation on this a while back.

On 6/4/2014 10:03 PM, David Nighswander wrote:
>> From: Adrian Jones
>
>
>
>> As for sharpening, could you make some lengths of wood the exact profile and
>> glue on various grits of sandpaper?
> Your question triggered a memory.
> In ancient times early Galoots used a very convoluted process to create such a
tool.
> The long drawn out explanation is here:
> http://books.google.com/books?id=v98DAAAAMBAJ&pg=PA330&dq=make+emery+
wheels&hl=en&sa=X&ei=V86PU8zfHIGYyASqzIKoBw&ved=0CEAQ6AEwAA#v=onepage&q=make%20e
mery%20wheels&f=false">http://books.google.com/books?id=v98DAAAAMBAJ&pg=PA330&dq
=make+emery+wheels&hl=en&sa=X&ei=V86PU8zfHIGYyASqzIKoBw&ved=0CEAQ6AEwAA#v=onepag
e&q=make%20emery%20wheels&f=false
>
>
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