[TheForge] Spring steel (and other) breaking in mild acid

[Larry Ruebush]

What I am going to discribe may or may not be along the same line as what 
you just discribed.
At old farm show I have seen large saw mill blades hammered. I never have 
really understood what the man was doing, but he runs his hand over the 
blade, makes some chauk marks and then starts hammering. He uses special 
looking hammers.
I am guessing that this is to staighten the blade and maybe put a dish in 
it, but a dish doesn't make sense.
Anyone with a better explanation?
Larry Ruebush
west central IL
----- Original Message ----- 
From: "Mike Spencer" <mspencer at tallships.ca>
To: <theforge at mailman.qth.net>
Sent: Saturday, August 27, 2011 4:51 PM
Subject: [TheForge] Re:Spring steel (and other) breaking in mild acid


>
> Andrew Vida <osan at netlabs.net> wrote:
>
>> AKA work hardening... similar to autofrettage in artillery barrels...
>
> I read that as "autofrottage in artillery barrels". What you get for
> sharing an artillery barrel with somebody else.
>
> Never heard of autofrettage.  Thanks for the new word.
>
> I spent most of today at a hand mowing competition.  I wanted to see
> if I could pick up some pointers on my style but mainly I wanted to
> learn about "peening a scythe blade".
>
> The serious competitors use blades broader than those normally sold in
> farm supply stores.  It appears that the latter are drop forged while
> the former show signs of some degree of hand forging.  All the ones I
> looked at were made in Austria and were quite thin. As well, they
> showed little pukky marks of being hammered all over on the top surface
> with an almost pointy hammer.  I'm guessing that this hand-, air- or
> treadle-hammering is done to cause the slight dishing visible on
> blades so marked.
>
> But that's not the "peening" deal.  To obtain the finest edge, the
> blade is place on a polished cylindrical little stake anvil (axis of the
> cylinder parallel to the edge) with the edge very near the crest of the
> anvil's curve.  Then it's hammered firmly but not very hard with a
> polished crosspeen *very* near the edge.  The orientation of the anvil
> and and hammer are such that the metal is drawn toward the edge but
> not (very much at all) along the edge (which would lead to totally
> unacceptable rippling.)  All done cold.
>
> The guy giving me the tutorial said that most typical North American
> blades won't respond well to this treatment but that the Austrian
> blades can be peened to an edge so thin that it can be flexed slightly
> with a thumbnail. He didn't make the edge of his demo blade quite that
> thin but almost. And there was no visible rippling.
>
> All very interesting. Nobody at the meet (that I talked to) had any
> hard metallurgical facts about the alloy or factory heat treating on
> these Austrian blades.
>
> I have a regular store-boughten blade of the probably-drop-forged
> variety with which I'm only moderately proficient compared to the
> better competitors at the meet.  I also have a wide one with elaborate
> (but not readily readable) maker's marks that's clearly hand forged --
> there are obvious fuller makes near the heel and other details.
>
> So now I'm going to have to see what I can do about fixing my blades
> up to work as well as the ones the competitors use.
>
> Another feature of the competition was the remarkable variety of
> custom snaths and nibs, most of non-adjustable but made to fit the
> stature of the owner, in both bent and welded aluminum and in finely
> crafted wood.
>
> - Mike
>
> -- 
> Michael Spencer                  Nova Scotia, Canada       .~.
>                                                           /V\
> mspencer at tallships.ca                                     /( )\
> http://home.tallships.ca/mspencer/                        ^^-^^
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