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Hammer size vs Anvil Size

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There was a discussion in the IForgeIron Blacksmith Chat Room about hammer size vs anvil size.

Let's say the anvil weighs 100 pounds (an easy number to work with) and is securely attached to the stump or stand. The smith works 40 hours a week and 50 weeks a year. This would be a full time job with lots of use for the anvil.

1. What weight hammer can be used with NO damage to the anvil under these conditions.

2. What is the size stock that can be used on this anvil for an extended perion of time with NO damage to the anvil?

3. If it reasonalbe to conclude that if you double the size of the anvil (100 pounds to 200 pounds) you can also double the hammer weight and stock size?

It would seem small stock suggests a small hammer and a small anvil, and large stock suggests a large hammer and a large anvil weight. But is there some type guidline that a particular anvil weight would suggest a particular hammer weight and stock size that could be used on a regular basis?

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I have read several times that a ratio of 3/100 is a good one. That is, for every 3 pounds of hammer, the anvil ought to be no less than 100 pounds. So if one expects to do a lot of striking with an 8 pound hammer, then the anvil ought to be 240 pounds or more.

This discussion used to come up a lot because of power hammer design and construction, since it is unreasonable to try to keep that ratio past a certain threshhold. For instance, a 300 pound hammer would be expected to have a 10,000 pound anvil, which is about what the whole hammer of that class usually weighs.

So the weight ratio is just a guideline, and depends on the type of use.

In theory, the anvil will never suffer damage as long as the forged piece is always hot, because it will be softer than the face of the anvil, regardless the size of the stock. In practice, we all straighten and bend cold iron on the anvil, and we all occasionally miss. I think wear and tear on anvils comes from this work, not the hot work. With several hours of continuous hot forging, the anvil face will get hot enough to steam water. But not hot enough to alter its heat-treated condition. At least I've never seen nor heard of that happening.

As the stock gets larger, it is usually easier to work on a larger anvil both because of the increased work surface, and the greater stability. But the size of the stock alone should not have any bearing on the wear of the anvil.

I know St. Francis used a smaller anvil and was adamant that it was enough. However, I have 4 anvils remaining... a 127# London pattern PW, a #500 London pattern Fisher, a 119# (50K) double-horn Czech, and a 260 pound double-horn Czech. The only one I use regularly is the 260 pound Czech. The reason is that top is more flexible. I can do small stuff at the narrow end of the flat horn, but I have a good working surface and fairly stable anvil for normal work.

I also think a larger anvil can be better for small work, because the hardie hole is larger so you can make more stable tools. I have made many one-piece roses using a hardie tool with a shelf that I made. It would be nearly impossible to do those petals using only an anvil face, yet a smaller anvil wouldn't support the tool I needed as well.

There are ALWAYS work-arounds. But in my opinion, the most flexible general purpose anvil is a 200 - 300 pound double horn, like the Nimbus, Pettinghaus, Old World, or Euroanvil.

If you never missed with the hammer, or beat on the anvil with cold iron, I bet you could work on any size your entire life and when you died it would look about the same as when you bought it.

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Let's say the anvil weighs 100 pounds (an easy number to work with) and is securely attached to the stump or stand. The smith works 40 hours a week and 50 weeks a year. This would be a full time job with lots of use for the anvil.

(Q) 1. What weight hammer can be used with NO damage to the anvil under these conditions.

(A) The anvil is a means to stabilize the hot piece being worked with the hammer, you don't work the hot piece with the anvil and the hammer should never hit the anvil face.

(Q) 2. What is the size stock that can be used on this anvil for an extended perion of time with NO damage to the anvil?

(A) Makes it sound like you are torturing the anvil. LOL You can work any size stock you are capable of handling with whatever size hammer you are comfortable using. Again the hot pliable stock is laid on the anvil for stability, you are hitting the soft pliable stock with the hammer.

(Q) 3. If it reasonalbe to conclude that if you double the size of the anvil (100 pounds to 200 pounds) you can also double the hammer weight and stock size?

(A) See answers to part 1 and 2.

Conclusion - Hammer size to anvil weight ratio is not relavent, working hot iron versus cold iron is relavent. If you are capable and comfortable using a heavier hammer, use it. I see no point to using a small hammer to beat a piece to death when you can use a heavier hammer to get the job done and shorten your time at the anvil, save fuel and thus use the anvil less to lessen the abrasion wear to the face.

An anvil does not absorb the blow from your hammer, the hot iron does. Size of the anvil face determines what you can do on it, and thusly a larger work face means a heavier anvil.

If you look at an anvil that was used primarily to sharpen plow lays which is a very thin section, over a period of 40 or 50 years the sweet spot where 90% of the work is done will be a little sway back from what is called crushing, the face gets pushed down a smidgen from the continual work at that spot and the soft wrought underneath will swell out to the sides just a tad, or sometimes the face will wear off just a tad from abrasion and make it swayback.

my2¢ worth

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I concur with both of the opinions above and would like to add some comments with regard to the potential for damage.

The old wrought anvils did collapse from repetitive work, but that is no different from many more modern tools that are used and abused. When I decided to rebuild it, my old Peter Wright had collapsed at least a half inch from plow sharpening but the hard face was able to follow and did not fail drastically by coming off in large pieces - a testament to the original manufacturer. Of course, most of us have seen faces that were destroyed or failed. When they were in common use, anvils were produced as a business enterprise and were considered a commodity. As such, some makers produced marginal ones, even the name brand guys made mistakes occasionally. Add to this the fact that anvils were not treated with respect by the majority of users and you see why so many are in bad shape.

Our local historical society has a 310 lb Hay Budden anvil that was in a shop since it was new. The shop was in a farming community and passed from father to son so was in continuous operation from 1900 to 1965. The only marks on the anvil are some gouges from a cutting torch on the horn but the face is still pristine. This despite the fact it very likely saw daily, heavy use for many years - in fact, the society has a picture from the 1920's with the anvil shown alongside one of the boys and a big pile of sweeps. There were three forging stations in this shop and this anvil occupied one of them so the work was much harder than the average hobby shop.

Like Ed and Jr said, I believe damage primarily comes from abuse and ignorant use by novices, rather than honest hot work. With all this said, a larger anvil may make for a better surface due to the greater mass but that is a separate issue apart from the possibility of incurring damage.

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All of these points make perfect sense to me as an ex-Mechanical Engineering major, but the current History major neds to ask, Why?

If there were no benifit to havig an anvil with a larger mass, then why even bother having a 500# anvil?

It seems to me that the two points in which the hot metal is being squeezed between should have the largest mass possible, yet remain practical. No 10,000# anvils or 300# hand-hammers (I know the earlier reference was to a power hammer, I'm just making a point).

This is the way I'm picturing it:

If you have an anvil of mass X, lets say 100 pounds. That mass is spread out over a relatively large area compared to the stock that you are working. And your hammer (again, a hand-hammer) only has a striking surface of maybe a maximum of a 3 inch circle. The mass of the anvil that is directly under the stock and hammer is doing all of the work in moving the metal.

However, there are two reasons why having a larger anvil could be better:

1) The larger anvil face helps to support the stock so you don't have to hold the full weight of it, as well as give you an easily accessible place to put your hardies and other anvil tools (where else would you put them BUT the anvil?)

2) Having the full mass of the anvil spread out gives the anvil stability.

Something else to consider:

I am also debating whether having the mass of the anvil spread out helps the anvil absorb some of the force of the hammer. This may just be me trying too hard to think of things though A larger surface area spreads the force applied to it evenly. It might possibly be better to have the entire anvil mass concentrated into a cylinder the same diameter of your hammer's striking surface. Using the onlinemetals.com weight calculator, I've found that a round bar of 1018 cold rolled steel 3 inches in diameter and exactly 4.16793 feet long would have a mass of exactly 100 pounds, and cost just about $US175. Not an unreasonble price for a 100# "anvil". I'm not sure about the steel type, if someone could give me a better steel, I could do it over again.

So if this bar were FIRMLY supported in the ground, it would offer you 100#s of mass directly under your work, and may help move the metal easier. And is essence, if you had an anvil that was just over 4 feet high in all areas, then no matter where you hit, it would be 100#s of mass under your hammer. But that would have to be moved with lifts and stay there. It would probably weigh about 900#'s.

Maybe I should switch back to Engineering...

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hi all...

but my hammers are mainly square...

and its logical not to use a BIG sledge on small work....

A it will break the work

B you know it will do damage.

and there aint really a way to prevent damage to the anvil...

some can try. but accidents happen....

and solong as the hammer survives its all good...

from PC aka brett.

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I think we're reasonably close to a definitive answer.

I would say (after some thought) that the ratio is not as close as I would have previously thought, and does not necessarily increase in a linear fashion.
Also - like Irnsrgn says, the majority of the damage is done when you *miss* the work piece.

I think the answer is in inertia, and the pressure exerted on the face of the anvil, due to force acting through that hammer over a very small contact area.
This area is not going to increase proportionally with any increase in mass, so a larger hammer will have a greater pressure.

I think Rantalin was correct in saying the only part of the anvil moving is directly under the anvil.

Short answer - I think it depends on the anvil, largely, but I would say the relationship between hammer and anvil weight would follow a curve. Smaller anvils would, IMHO be able to handle a larger hammer better, pound for pound than a larger anvil would be able to handle a proportionally larger hammer.

Just my $0.02, but stay tuned for more after a good night's sleep. :)

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I seem to have opened a can of worms on this subject so I want clarify if I may. My original comment was about the anvil stand itself. It seems logical to me that a stand that will adequately support a 100# anvil and using, say, a 2 -3 pound hammer on a regular basis i.e. a 40 hour work week, may not adequately support said anvil when the work changed to the use of, say, a stiker swinging a 12# or larger hammer. Am I toally off base with this logic? I understand that you would want to make a stand as sturdy as possible but if you wanted to make it light weight for, perhaps, portability, you may have to sacrifice the use of heavier than usual (I know "usual" is arbitrary) hammers. Correct? :)

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There has been some good points brought up in this discusion. Although in my thinking - don't forget there is an equal reaction for every action. So for a bit heavyer anvil during use there will be less amount of energy transfered through the "hot" metal (which most of the energy is absorbed by) and into the stand. Therefore the stand I would say really only needs to support at most 1-1/2 times the anvil weight - I'm not an engineer though. The anvil acts as a backstop for the hammer blows against hot metal. Although like everything - people use what is available at the time to get the job done. There is nothing wrong with that and I don't forsee an absolute answer for the anvil to hammer ratio due to the fact that everyone has different working methods, styles, resources and tools (whether boughten or home made). Just something to think about. I think the key to most of it regardless of the size of anvil is that it will be easier to move metal when it's "HOT" and with a subtantial weight of mass below it. Point or no point take it for what it's worth - Jeremy K

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Hi all.. I know this topic is just kinda winding down, but I just ran across this, and it might prove interesting

Link removed at the request of anvilfire

Just read over in the Guru's den that if you have an older anvil, smaller is often better, as it was apparently harder to quench a bigger anvil properly, as a bigger anvil cannot be cooled as quickly as a smaller anvil.
Slower quenching, as you all know results in a softer anvil.

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Mr Smith: It was just as easy to screw up a small anvil as a large one. I've seen many delaminated small anvils. I worked on lots of older larger and smaller anvils and the larger ones have been just as good or better than the small ones. Further, if the edges of a small anvil are damaged (a real problem if the face is too brittle because it was cooled too quickly), you don't have a lot of anvil left to dress the edges.

Within reason, the face of the anvil doesn't have to be THAT hard. It just has to be harder than what you are forging, including the occasional mild steel cold work. Over the decades, the older anvils did work harden somewhat anyway.

In my opinion, that board's justification for a small anvil's superiority is just speculation and bunk. Good anvil makers knew how to adjust their heat-treating for the size of the anvil.

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I didn't read the 'anvilfire' discussion but that sounds a wee bit far-fetched. I don't think large anvils were more likely to fail over the long run because they were not to the same quality as smaller ones. If that were true, everyone would want a small anvil and there would be no big ones in good shape. The bigger anvil manufacturers produced anvils just like any other company which is formed to make a product and a profit. Some of everyone's final product failed over time and much of it performed well. Smiths who used their anvils and cared for them as an important tool often passed them down to following generations while the reverse occurred in other shops. As mentioned earlier in this thread, Whitaker had a 150 lb anvil most of his working life, which suited his type of work - but I think his focus was to concentrate on the finished work and not collecting tools.

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For the record, I agree wholeheartedly with Irnsrgn. The majority of the damage is done when the anvil is struck, rather than the workpiece. The larger hammers cause greater anvil damage, I think, pound for pound than smaller hammers when you miss the work, but that's a different story

IMHO, it seems altogether plausible that cooling 200+ lbs of tool steel using 19th or even 18th century tech could be problematic. All it would take would be a few batches of anvils to fail, and, well you know how misinformation gets spread, particularly in the field of 'smithing.

I'm not trying to support or promote any size of anvil over another, or indeed, any one website over another - just trying to look at factors that could give a reason why one always finds this hammer:anvil weight ratio popping up all over. It just keeps coming back to not missing your workpiece and damaging your most valuable tool.

I just thought this might be another angle on what seems to be a perennial topic.

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Some years ago, Anvil's Ring magazine had an article on an anvil shop still making them the old way with wrought body and welded face into the early 1970's. I seem to recall it was located in Germany but maybe not - perhaps someone has the issue and can fill in my lousy memory. At any rate, I remember they were located next to a river, which provided power for the power hammer, bellows, grinders, etc. This was still primarily a manual process, with lots of muscle and sweat expended to get the final product. Their quench method was to run a 10" pipe from the river with natural flow and a dump valve somewhere in the line. The anvil was finished to the point that it was ready to harden and scooted under the pipe, then everyone stood back to let the water and steam fly. One of the comments in the story mentioned that sometimes the face plates broke violently and flew off when there was a failure in the forge welds. Seems like the process has always been a bit unpredictable.

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From what I have read there is a definate ratio of hammer to anvil size. There was a discussion of this topic on Anvilfire a while back and I think the accepted figure for continuous use was about 50:1 that is 50 lbs of anvil for every 1 lb of hammer.


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Woody: I never accepted that. Of course I never spend any time on that board, so it was probably hard to count my vote, eh? :)

Seriously, that is VERY arbritrary, as we've already said in our posts right here. Further, it isn't linear. Once you get above some decent threshhold for your own purposes... say 100 pounds or so... then the anvil doesn't have to keep getting bigger to get good performance with a bigger hammer. For example, one can quite comfortably use a 200 pound anvil striking with an 8 pound hammer, with good performance. That is only a 1/25 ratio.

Of course the mounting of the anvil probably gets more important as the pounding gets more vigorous. A decent stand with good mass and secure binding contributes considerably to the stability and performance of the anvil. A well-mounted 150 pound anvil will be much more satisfying to work on than a loose 300 pounder on a wobby metal stand.

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...a simple physics experiment might lend some insight...

Let's not make this too complicated, though...

say you have a piece of 1/2 round bar at a nice forging heat and you are holding it "out in the air" and strike it with a hammer, what amount of work is done to the bar?
intuitively, very little right? the bar will have the kinetic energy of the hammer transferred to it and one of two things has to happen--the energy is transferred or work is done (which is really a transfer of energy, too) since we don't figure much work is done the kinetic energy of the hammer is transferred to the bar and whatever is holding the bar.

now take the same "work ready bar" and have an assistant hold out an 8# sledge in the air--using the same hammer with the same velocity and the sledge as an anvil--I would figure that more work would be done on the bar, correct me if you disagree...
more of the kinetic energy of the hammer will be devoted to "work" (deformation of the bar) because there is a reaction at the face of the sledge in that it takes a lot more energy to accelerate that mass (remember that the user is supporting the face of the sledge in the air via the handle and that person will also have energy transferred to them)

Likewise, with a larger AND better supported anvil more energy can be transformed into work.

So as anvil size increases more theoretical work can be perfomed on it.

Here is where it all goes south, kind of...

If the anvil, of whatever size, is supported WELL by a stand (...and the stand by the floor, and the floor by the fill/foundation, and the foundation by the earth, etc.) and the kinetic energy of the hammer blow is attempting to accelerate the earth (the planet) then the work done by the blow is maximized.

Now, examine the great anvil and stand in irnsrgn's post, and consider attempting to use it while being supported by a peat bog, or a piece of foam rubber, or on springs; and the anvil will be isolated (partially) from the mass of the earth and the amount of work performed on the piece will be diminished.

I think that the size of the anvil is not really as relevant as whether or not the anvil is well supported.

How well supported? I think that irnsrgn has made a convincing argument that a stand can be light enough and "strong" enough all at the same time.

Seeing everyone else has an opinion, there's mine, too...

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Ed if that theory is correct, then all we need is a slab of tool steel on a secure mount. Not all the energy of the hammer is transferred directly to the mount, it has to pass through the anvil first and if the hammer is too big it will damage the anvil even though it never directly contacts the anvil. I have knowledge of one 150 lb anvil being broke in half by using a 10 lb sledge on it. We gnash our teeth at the thoughts of a chisel being used on the face of the anvil, but then look the other way when a big hammer is used on a small anvil because the damage isn't always immediately apparent. You pound on anything long enough with a big enough hammer and you will break it.


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All posters have valid points and this would certainly be an interesting confab face-to-face.

When I first obtained my 250 PW, I set it on a stump with no tie downs. Not only did it ring but I chased it around the stump. This was with a 3 lb hand hammer and no sledges. This movement was wasted energy - as H8 illustrates so clearly.

The Japanese and certain other traditions put a block anvil in the ground and dig a hole to allow the smith to reach the correct height. Could this be the perfect method of securing the anvil? I can't say since I haven't used this way but using a good quality anvil on an angle iron frame, or a stump, or a concrete base, etc., all seem to be reasonable practices. I don't believe any are incorrect.

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HW's post reminds me of when my uncles old shop, he was the third owner, was bought by the paint store next door as an expansion and they tried to remove the anvil stump.

It was set in the old way, by burying a log and letting the right amount stick up. They tried everything to move it, then started digging. After going down 6 feet and still not being able to move it, they just cut it off with a chain saw. LOL

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