16 years ago
rec.crafts.metalworking on 8/31/06.
The thread changed migrated from knives to lawn mower blades, so
here I am.
Last week at a threshing show, a guy brought me a brand new mower blade
to flatten and then to bend 2 or 3" of each end up at 90 degrees to make
a hand pushed sod cutter.
I have used and sharpened a lot of mower blades and have seen some
past posts on this topic, but opinions and experiences seem to vary widely.
Here's my most recent experience:
I heated this blade to about 1900 degrees F and forged down the
"wings". I let it cool until there was NO color in it all, then
quenched it in water. It got hard as glass and shattered off about the
same 2 inches that I quenched when I hit it with a hammer.
To me, this said that the material was Not water hardening, but
rather oil or air hardening stock.
So, I reheated it gently,let it soak a few minutes and then slowly
moved it from the fire to the coals a few inches away over a period of
about 2 minutes, then let it cool to room temp for 10 minutes or so.
The stock became soft enough to file easily. I conclude it had to be
oil hardening (NOT air hardening), or I would not have been able to
anneal it with the above process.
I believe that (if this blade is similar to the blades I use on my Cub
Cadet mowers) these blades are left in the annealed condition after
forming and sharpening so they don't shatter or crack in service.
Would they make good knives? Who the heck knows, if you don't know the
exact analysis of the material. Why spend hours at the grinder or
whatever to produce something that might or might not work. The
parallel for me is in making blacksmithing tools. I have chosen 3 kinds
of material (S1, S7 and W1) for my struck tools and I know how to work
each and when to use them.
Even worse to me, would be to use mystery metal for a tool that I was
going to sell to someone else.
When "mystery metal" works is in a "McGyver" situation where you
have to do SOMETHING, right now, and getting the exact right stuff is
out of the question.
Throwing away old mower blades, I remain