Anvil resurface

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:

Thanks. the thing is pretty hard, gives a nice "bouce", and it's not bad, I was considering truing it to mallet sheet aluminum out flat, but have a better plan. I found a 6x24 inch slab of 3 inch steel plate in my garage that I will surface grind one side of for a benchtop sheet metal anvil. I don't have a torch big enough to heat treat that monster, so will just re-grind as necessary.

Old anvils were cast with high carbon iron/steel, then quenched in water. Fishers were cast with a high carbon face. Then quenched in a stream. Very hard, but edges chip easily.

Modern anvils are now tool steel and more extensively heat treated.

Resurfacing an anvil, I'm told, is done with welding to build up a surface of good hard steel, THEN beating or grinding it flat. The core of the anvil might not be good steel, grinding down to the core wouldn't be helpful.

That's cool! Better add handles on the ends - that's a heavy sucker. I'd like to find a piece like that - you have a better garage than I do .

I don't have a torch big enough to heat treat that monster, so

And if you only use a soft mallet (wood, plastic, leather), you'll never have to re-grind.

Bob

I fly-cut the top and bottom of the anvil in the mill first to make it sit flat on the mag chuck. It weighs only 0-1-8 Lbs so it didn't overstress the grinder. The top plate is harder than the wrought-iron body but a file does cut it. It's an English 'Wilkinson', no first name or logo stamp implying Joshua Wilkinson made it (?). Being so small it wasn't damaged by heavy use and I only ground the center smooth, leaving a few small dents and the rounded edges which are useful for shaping strong rather than decorative tools. The remaining dents have shinier rings around them which look like the skin of cast iron after grinding a cross-section of it, so apparently there is some work hardening.

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?

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 have never heard that one before. My anvil says "chrome alloy" on it, but no name. I just happen to have a box of ball bearings up to 3 inches on the shelf behind it. A one inch ball bounces back 7.5 inches on mine.

Stu sez: "I have never heard that one before. My anvil says "chrome alloy" on it, but no name. I just happen to have a box of ball bearings up to 3 inches on the shelf behind it. A one inch ball bounces back 7.5 inches on mine."

That seems to lend a bit of credibiity to what I think I heard. Upon further reflection, I wonder if my source wasn't referring to a specif heat treat on a specific anvil.

Bob Swinney

up to 9" if the anvil

I've heard of building your own hardness tester using this method.

You need some known items of hardness for calibration though. Find some glass tubing maybe 10-20 inches long that you can make marks on and your steel ball will easily slip into. Using a known surface drop the ball (from the same height) and note (mark) how high it bounces up. Repeat several times and take the average. Repeat process on another known item. Test your unknown item and note how high the ball bounces.

up to 9" if the anvil

See:

before I retired, the technical data centre manager showed me one and asked if it was worth keeping or if I wanted it, wish now I had taken it instead of explaining (and showing him on one of the exposed building columns) how it was used to estimate the strength of materials. Gerry :-)} London, Canada

nd back up to 9" if the anvil

someone confirm?

My scleroscope rebounds to 4 of 10 off my anvil, which definitely has a plate welded on the top. A carpenter's hammer reads the same, a HSS bit held in the milling vise reads 6. The anvil can be filed with some difficulty. It's fine for hobby work.

It's quite difficult to get the same reading repeatedly off small samples even when they are clamped in a vise, and this is a professional instrument, although an old one in suspicious condition.

I would hold the glass tube upright with a level to minimize friction and record the rebound against a ruler with a digital camera video.

Jim Wilkins