[TheForge] File Making

[David E. Smucker]

There is a very interesting section on file making in the book, Metal 
Working  A Book of Tools, Materials and Processes for the Handyman by Paul 
N. Hasluck.  Original USA copyright date of 1907, but it is a British book 
and author and predates this USA date by a number of years.  Lindsay 
Publications, Inc. has a reprint of this book.  It is about 760 pages with a 
good index.

It details the tools and methods for hand cutting of files.  The steel being 
used is high carbon plain steel and the teeth cut in the annealed state.

Here is part of what it says about the heat treating:

"Previous to being hardened the files are drawn though beer grounds, yeast 
or other sticky matter and then though common salt mixed with hoof parings 
previously roasted and pounded;  this compound protects the delicate teeth 
of the file from direct action of the fire, and serves as an index of 
temperature, as on the fusion of the salt the hardening heat is obtained; 
also the files are less liable to crack or clink on being immersed in the 
water."

Now the "roasted and pounded hoof parings" were a common source of very 
clean carbon so some carbon would for sure be present in the mixture. 
(Yeast / sugar too is mostly carbon) but my understanding is that the steel 
used was always high carbon for hand making of files.  This mixture would 
provide some case hardening effect, but the time of contact is short. (Case 
hardening is contact time dependent for depth of carbon into the steel.) 
It seem much more likely to me that the function is to protect the teeth, 
prevent decarburization and as noted give a good measure of critical 
temperature.

Dave Smucker
Brasstown, NC

ps, still having problems sending to theforge, this is a resend.

----- Original Message ----- 
From: <wmullett at bright.net>
To: "Sponsored by ABANA" <theforge at mailman.qth.net>
Sent: Wednesday, March 19, 2008 7:57 AM
Subject: Re: Re: [TheForge] Re: File making in Japan


> Andy didn't say this was not case hardening - he said modern files are 
> hardened in lead.  That's not what is happening here.  This is a hand cut 
> file process using old methods and it still looks like case hardening to 
> me.
>
>
> ============================================================
> From: "David E. Smucker" <davesmucker at hotmail.com>
> Date: Tue Mar 18, 7:47 PM
> To: "Sponsored by ABANA" <theforge at mailman.qth.net>
> Subject: Re: [TheForge] Re: File making in Japan
>
> I with Andy,  I think it is highly unlikely that hand made Japanese files
> are case hardened.   The Japanese are noted for their very high carbon, 
> very
> high quality steels used for hand tools, woodworking blades and such.
>
> Dave Smucker
> Brasstown, NC