Anvil size vs hammer size, 2% or 10:1 or 15:1

[Glenn]

There has been a lot of numbers thrown around for anvil size and hammer size.

 

I have seen where a hand hammer should be 2 percent of the anvil weight. That is a 2 pound hammer on a 100 pound anvil. This is suppose to be the *correct* ratio as to not damage the anvil with use. I have also seen comments that 3 and 4 pound hammers can be used but not for constant use as it will start to deform the anvil. 

 

WHERE DO THESE NUMBERS COME FROM?

 

Did someone long, or not so long, ago threw a guess into the air? 

 

Did it take hold like a urban legend and every one else repeat the number because it sounded like it had validity?  Or is there research to prove the number?

 

WHERE DO THESE NUMBERS COME FROM?

What is the original source? Who made or chose the numbers? I am looking for where all this started, the research that determined the *correct* size ratio.  I realize a definitive paper is most likely not available but with enough people looking and discussing the subject we should be able to sort it all out.

[jmccustomknives]

I think I read in one of Goddard's books that a 1 to 20 ratio was ideal.  It had nothing to do with damaging the anvil.  Just physics of having enough mass to keep the anvil from bouncing around.  (which could make it fall and damage itself and ones foot!  :blink:

[Jim Coke]

Greetings , 

 

I do not think a ratio has any factor what so ever...  The hammer and anvil size is directly proportionate to the work to be done..  I work off several anvils ranging from 80lbs to 500lbs..  If this was true I would have to switch from a 1lb to 10lb hammer when I changed from anvil to anvil..  Not in the cards... Granted you must be cautious when working on smaller anvils.. I would like to see someone knock over my 500lb Trenton with a hammer.. LOL

 

Forge on and make beautiful things

Jim

[thingmaker3]

Mechanical efficiency drops as the ratio of hammer mass to anvil mass goes up. There's a knee in the curve around 2 or 5 percent.

No risk to breaking the anvil body - just an engineering curiosity. Do be careful with sledges on the heel or horn, of course.

[SmoothBore]

Quote

WHERE DO THESE NUMBERS COME FROM?

 

In my opinion, ... they were pulled directly from someone's back-side.

I choose my hammer, based solely on the job at hand.

Three and four pound hammers are my most popular weights, ... with a 2.5 pounder being my "light" hammer, ... used primarily on a #177 Peter Wright.

There's a #110 "portable" Trenton sticking under a bench, ... but I've rarely used it for anything, ... and have no real experience with smaller Anvils.

[MLMartin]

Anvil mass location makes a huge difference. I have a block anvil that is 6" square and 12" tall. It is around 120lb. I dare say no person could reasonably damage this anvil with a 20lb sledge as long as they were hammering on hot iron. Now if you have a 120lb hay budden anvil I think a 20lb sledge would be to large for this anvil, at least certainly to big to be striking heavily over the horn or heal.

[Glenn]

The hammer to anvil ratio should remain constant no matter the size of the anvil (I would think). A  2 pound hammer on a 100 pound anvil, would be 4 pound hammer on a 200 pound anvil, and a 20 pound hammer on a 1000 pound anvil. A smaller hammer should not cause a problem, and at times a larger hammer (within reason) could be used. 

 

Yes we should choose the right tool or the job at hand. A 100 pound anvil can work up to 1/2 inch, 3/4 inch, and even on occasion, 1 inch material. The 2 pound hammer is now the limiting factor. A 2 pound hammer is a bit light (in my opinion) for 1 inch stock.

 

If you are working 1-1/2 or 2 inch diameter or larger stock, you NEED a bigger anvil and a bigger hammer.

[Ridgewayforge]

I use a 35 pound railroad rail, and I use it the less-dynamic way, hammering on the top of the rail with a 4 lb hammer. No deformation, no breakage... I think too many factors play into this to be a good cut and dreid number.

[Glenn]

Mechanical efficiency drops as the ratio of hammer mass to anvil mass goes up. There's a knee in the curve around 2 or 5 percent.

No risk to breaking the anvil body - just an engineering curiosity. Do be careful with sledges on the heel or horn, of course.

 

Can you please provide a reference for this curve.

 

If we can assemble the source information, then we can better understand the ratios.

[thingmaker3]

I found a more eloquently phrased version of what I said above: http://phoenixhammer.com/anvile.htm

 

All of this simply means a bigger anvil is a better anvil. But we already knew that. :P

[Gerald Boggs]

I have no idea if the information has any application to an anvil and hammer.  Back in the Seventies, a whole lot of knowledge was created that has little to do with reality.  Here's what I do know:  I have four anvils.  I started with a 600 Lb anvil, went to a 400 Lb anvil, then to a 218 Lb, than I bought a 100 Lb anvil.  This last has become my main use anvil, the rest collect dust.  I routinely forge 1 1/8 on my 100 Lb anvil without feeling that it's undersized.  As I have no power hammer, everything I forge is done on that anvil.  I am a full-time smith, the mortgage is paid by what I forge.

[Robert Yates]

My thoughts on this is less science and more of the need . that being said lets take a look at simple ways of the craft.

 

a jeweler uses very small hammers and very small anvils to work gold, silver, and various metals to his craft .

while a blacksmith will use the larger anvils 100 + and a vast array of hammers depending on his needs (he will even invent different hammers to do a specific jobs)

there are many types of metal workers that range from very simple to very complex works and I really think it comes down to the "Need of the craft work at hand"  I Understand that anyone that digs into the history loves to analyze and tries to get the scientific meaning of of things in the world .

 

I would pose this the Anvil size to Hammer size is not of a ratio (scientific principles) yet would be the pure function and Need to complete the project at hand by a craftsman in their field . 

[Glenn]

Not for hand hammers but for power hammers

Phoenix Hammers,  Anvil "efficiency" of forging hammers
 
So, the "efficiency" of the anvil is based upon the total potential energy of each blow (100%), and expressed as the useful percentage of that energy that is available for deforming the workpiece. Beyond a 35:1 anvil/ram ratio, the efficiency is already 90% or better, and increasing the anvil weight much further than this results in rapidly diminishing return in forging effectiveness for the investment in material. Anvil/ram weight ratios of 15:1 - 25:1 generally produce the most effective forging for the total cost associated with building and powering a given forging hammer. In hammers of 10,000lb or greater ram weight, 35:1 or larger anvils may be advisable to keep damage to surrounding property to a minimum.

thingmaker, thank you for the reference

[Judson Yaggy]

There are a few threads on this in the power hammers section, and in those threads are refrenced a chart from Chambersburg Engineering Co. showing POWER HAMMER tup to anvil ratios.  The gist of the chart is that minimum shoud be about 10:1, there are diminishing returns beyond 20:1, and 15:1 seemed to be a sweet spot on the cost/benifit curve.  There is also a link somewhere here to a Japanese engineering paper placing the ideal ratio somewhat lower.  

 

On a power hammer all of the anvil mass is directly below the hammer head.  On a hand forging anvil this is not true.  If you work on the horn or in a swedge in the hardie hole, (or do much of anything more than forging a simple taper or beveling a blade) there is significantly less mass under the hammer and the overall mass of the anvil would need to go up if you wanted to maintain mass under the hammer.  

 

However, when hand forging your strength, endurance, technique, and hammer size are as important as anvil size.  One experianced guy working with a hand hammer is unlikely to damage any reasonably sized anvil, so if anone thinks they are suffering due to small anvil syndrome pratice more and slowly work up to a bigger hammer.  Striker, horn, and hardie work are of course exceptions to this.  

[quint]

Another aspect is the hardness of the anvil I would imagine. That article talks about the movement of the anvil (if even a very small amount) due to the imparted energy from the blow of the hammer. The hardness of the top plate or entire anvil will transmit this energy differently. 

 

This may play a bit into the larger and smaller anvil, I dont know from experience but I have read that sometimes larger anvils can be somewhat softer then smaller anvils and thus I could imagine this changes how the blow is felt or transmitted. 

Granted ya put a piece of soft steel inbetween the two and I am not sure how this affects the the ability of the hardness of the anvil to make up for its size and what not. 

[Rich Hale]

Let us not omit the user from this exploration. A given weight of anvil and hammer used by different smiths may be more or less efficient...But that only sorts out the smith wanna be's.....and they may be smiths of the future.

[Frosty]

The only legitimate hammer:anvil ratio I've seen raw data for is the power hammer ratio.

 

I only see two types of anvil damage on healthy anvil. Chipped edges and swayed faces. The cause of edge damage is pretty obvious, though I'm sure some clever folk have come up with other methods.

 

Sway is (IMHO) caused primarily by deformation of the anvil below the face steel. I've seen this most commonly in wrought body anvils but some cast bodies too. I've never seen it in a Swedish cast steel anvil that hasn't been through a fire or such.

 

I have seen a couple swayed anvils I THINK may be erosive wear but I don't know about the mechanics of that.

 

So, I THINK using too heavy a hammer on a soft bodied anvil, especially if it's a light weight or thin faced one could result in eventual sway damage. Chipping edges doesn't have as much to do with hammer weight but the heavier the hammer the more likely and more severe the edge chipping so don't miss.

 

Other than damage the anvil hammer ratio isn't such a big deal except for efficiency and overall hardness has almost as much to do with it as weight under the blow. For direct example, my 125lb. Soderfors moves metal FAR better than my 200lb. Trenton ad the Trenton has a taller waist so there's more iron under the blow but it's a soft wrought body. A bearing doesn't rebound as well from the Trenton as the Soderfors either. The Soderfors also shows no sway or marking on the face but there are some chips out of the edges. She's a HARD old gal but a sweetheart.

 

And them's my thoughts.

 

Frosty The Lucky.

[John Larson]

Interesting reading.  My experience with my power hammers is that 20:1 makes a more fun hammer than with the previous 16:1.  Way back in time I made I-beam spine hammers with a much lower ratio of about 8:1.  I moved on to better hammer designs before I did any anvil changing, and the better hammer designs used centered guides for much better control and rebound/percussion effects.  Thus,over time I have kept increasing anvil mass with improved "feel" and I rather expect that going higher would add the effect with some diminishing returns,  My littlest 50 pound hammer has a 25:1 ratio, but I have never built that unit with less anvil mass and cannot really say anything about mass change effects.

 

Most of the old tyme power hammers had too little anvil IMHO.  The Massey Clearspace hammers from the UK were perhaps an exception. 

 

I have used many different anvils for hand forging over the years.  My final purchase was a very large European anvil and I love its huge sweet spot (aka thick waist) and its massive top surface.  Its mass allows me to hammer sideways on occasion and it tends not to budge,  I seldom use hand hammers weighing more than 3 pounds. 

[Francis Trez Cole]

I would agree with the statement about the power hammer and a ratio. Is an important factor. and a power hammer can hit a lot harder than a human. That is why it is called a mechanical advantage.

Anvil size is not as critical. First Frosty will like this I went to the Juno museum of history. There is a blacksmithing display with tools and photos. Anvil and all tools had to be packed in so every thing was small the anvil weight was 50 pounds. the bellows was small also the tongs ans other items were regular size. Not only did the shoe horses but they fixed mining equipment of the time.

The Earth as a whole is the Heavy part of this planet if your anvil is connected to earth than you have all that mass behind it. Now look at Brian Brazeal's striking anvil. I made one in total it weight is 60 pounds and I use a 16 pound sledge hammer on it. the area of the shop where I have used it for the last 3 years the sand under the pavers has been compressed about 1/4". When I do demos I use it first because it is easy to move around. second if I have students striking its not my good anvil and if they miss and hit the face, its only mild steel. I have forge 3" stock on it with no problem.

I do not have anvil envy. Its not how big it is it is how you use it.

[HWooldridge]

On 2/1/2014 at 9:09 AM, Glenn said:

WHERE DO THESE NUMBERS COME FROM?
What is the original source? Who made or chose the numbers? I am looking for where all this started, the research that determined the *correct* size ratio.  I realize a definitive paper is most likely not available but with enough people looking and discussing the subject we should be able to sort it all out.

MT Richardson's "Practical Blacksmthing", which was written in the 1890's, has one entry that states a good outfit for general work is a 300 lb Eagle anvil with sledges up to 16 lbs and a hand hammer of 3-1/2 lbs. Of course, the sentence immediately preceding this one also states, "Opinions differ...".

James Drew's "Blacksmithing", written in 1935, recommends a 2 lb hammer on a 100 lb anvil (appears to be a minimum and bigger is implied as better).

My grandfather was a smith in the 1920's (like everyone else's g-pa); he used to tell me a 250 lb anvil was good up to a 4 lb hand hammer and 8 lb sledge but I have no idea how he arrived at that number.

My 250 lb anvil is fastened to a 300 lb block of concrete. We have used 16 lb sledges on it without anything scooting around.

I believe the two things we should be concerned about is the potential of damage to the anvil and lost energy if it moves when struck. Everything else is probably subjective to each smith's needs.

[evfreek]

A good starting point for those who are interested in the physics is "Physics of Anvils"
 

[bikecopXXX]

evfreek, that is a great summary paper.  makes me think of a quote:"it only works for spherical chickens in a vacuum".  i agree with Eric Chang's conclusions that anvil & hammer hardness determine rebound and e0 is the more correct method of predicting forging efficiency. (e0 assuming zero rebound, e1 assuming fully elastic rebound).

 

It sounds like there is a part 2 to the paper that is not included...any idea about that?

 

One thing he doesn't address is anvil geometry. A bigger anvil has a bigger sweet spot generally, but that sweetspot is even bigger if the waist is thick, as someone else noted.  Only mass directly in the shear cone under the hammer is fully effective.  That's why simple anvils of vertically oriented rail track and round or square bar feel so good for their weight.   Humans are puny and a few percent efficiency is easily noticed.  The bits outside the shear cone (horns) are less efficiently coupled to the main cone and are effectively attached to it by springs. 

 

so endeth the rant. 

[Gerald Boggs]

But is it a valid application of the math?  No where does it take into account securing the anvil to the earth.  In short, practical experience doesn't support his claims.

[thingmaker3]

Okay, Gerald, how big IS your hammer? :o

[John McPherson]

"In theory, Theory and Reality are the same, and you will get the same results. In Reality, they are different, and you will get very different results."

How many angels can dance on the head of a ball peen hammer?