Nice post, Pete. Thanx. FWIW I heard that a good test of a steel anvil was:

Drop a 1" diameter ball bearing from a height of 10". It should rebound back up to 9" if the anvil
surface is properly heat-treated. I'm not sure I believe this. Can someone confirm?

Bob Swinney
"spaco" wrote in message
...
If the anvil is made of steel, not cast iron, then it's face has been
hardened. "old" anvils would be plain carbon steel, somewhere between
about 1070 and 1095. Even though they were usually water quenched, the
section is so thick that the actual face hardness varied a lot. Some
are still almost hard as glass and some are so soft that the face has
actually been deformed toward the edges by the hammer blows and dished
out by use. This dishing is often called the "sweet spot" and some
blacksmiths (not me!)like it for straightening things, since when you
smack the part over the dished area it can overbend enough to exceed its
elastic limit, in a controlled sort of way.
Try filing on an edge to see how hard that one is. The horn and
everything BUT the face should be mild steel or even wrought iron if it
is old enough.
Modern anvils are often made of solid tool steel, 4140 being a
popular choice. They, of course are heat treated through and through.

I grind anvil faces for people on an old G%L model 35 (3hp spindle). I
push it real hard and take 2 to 3 thou per pass at .050" feed and medium
table travel speed. Lots of coolant. You probably know more than I do
about this, but the face of old anvils are almost NEVER parallel with
the base. I have seen them off by as much as 1/4". Attempting to
indicate them in can be frustrating since the face can be sooooo poor.
I have a piece of ground tooling plate that I lay upon the face when I
first sit the anvil on the table. I look for obvious humps and grind
them down with an angle grinder. Once the plate sits more or less in
the same plane as the face, I indicate on the plate and shim the base to
that. That way I have less metal to remove before the face is trued up.
Think about the actual use for the anvil and don't take any more
stock off than you need. A few dings in an area that you won't use
often is preferable to taking so much off that you get down in a softer
area of the face.
And don't be too concerned about the edges. Farriers want sharp
edges all around the anvil, but blacksmiths actually need rounded edges
to prevent cold shuts when shouldering.
So you may want radiuses of 1/8" or so up by the horn end tapering back
to nice and square back by the hardy hole or thereabouts. I try to
leave the edges on the heel sharp for hot cutting.

I never have been able to find out how much weight the table on my
surface grinder can take. Even calling the company 10 years ago or so
didn't get me any help. My machine is an 8" X 20" model and I can get
14 or 15" under the spindle. I try to limit it to about 140 pound
anvils. I don't know what I'd do if I "blew out" the hydraulics!

Pete Stanaitis
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Stupendous Man wrote:
I am thinking of taking my old anvil to work and using the surface
grinder to flatten it out.
Are old anvils heat treated, or just hardened by use?