Anvil weight vs stock size

[Glenn]

What size stock can routinely be used of each weight of anvil, without causing damage to the anvil for being too small or too light in weight?

On a regular stock size basis, when do I need a 200 pound anvil instead of a 150 or 100 pound anvil. (For the sake of discussion, let us resist the urge to mention power hammers.)

Is there a guide line or reference related to stock size and anvil weight?

 

 

 

 

 

 

[Fatfudd]

Interesting question Glenn-

I'm not sure size of stock is the determining factor or even an issue so long as the stock remains really hot and you use the appropriate size of hammer. I have easily worked 1" thick stock on anvils weighing under 100lbs using a 2lb hammer. 

Obviously, its easier to work thick stock on larger anvils because the mass of the anvil provides a more suitable rebound surface. Again so long as you maintain a high enough heat on the stock it will remain soft enough to be easily worked on any size of anvil. Where you get into more of an issue is the size of the working surface. For example if you want draw out a piece of 2" thick stock on an anvil with only a 3" face, you can still do it but the working surface limits the amount of work you can perform. You would wind up laying the piece long wise on the face rather than perpendicular across the face.

[Tubalcain2]

i've found the same thing in my experience.

[stan]

Was looking for information on this subject and found an old post on IFI July 7th 2006 by some guy called Glenn. larger stock being forged by hand, ie one hand, would probably be with a relatively light hammer, my heaviest is 4.5 lbs so should not damage an average size anvil.But if strikers are used with 12lbs hammers smaller anvils would likely be damaged.

[Kozzy]

Decided I better clarify this as opinion so be sure to take it that way.

Mathematically, it has nothing to do with stock size at all and would have everything to do with the energy of the hammer blow--after all, that's the only energy you are actually imparting to the anvil whether the stock is 1/2" or 3".   I was going to throw in some math but decided it'd be ridiculous.  It's enough to say that if your hammer weight and swing velocity wouldn't knock around the anvil with nothing on it, it still won't with a piece of hot iron, large or small,  absorbing a little of the energy.

Because the anvil is just a mass transferring that energy to the stand and floor, I'd say that the energy transition from anvil to stand to floor has a lot more to do with it being workable than just the mass of the anvil chosen.  Even a lightweight anvil that becomes a system with stand and floor can act like a 300 pounder under a heavy blow.  Ground and stand become part of the effective anvil-mass system in that case:  It all works together.

So...the choice to make is hammer weight and velocity of blow.  A badly mounted 300 pounder might take that as poorly as a well mounted 70 pounder which effectively transfers the energy through to packed floor.  Stock size being worked really isn't the question to be concerned about. 

Assuming high energy blows are involved, an edge hit is going to damage a big anvil about the same as a small one (ignoring horn and tail weakness).  A centered blow should transfer energy through the stand just as well on an anvil big or small if mounted well. Working with high energy blows becomes all about anvil construction details and whether it will fail at welds/waist/feet:  That's independent from total anvil mass.  Those kinds of details would vary by design and maker, not simply mass. 

It aint the size of the anvil, it's where the energy you transfer to it goes.

Hope that sort of made some sense.  Interrupted several times in the typing process.

[ThomasPowers]

Though you didn't include that very large anvils tended to be heat treated a bit softer and so a miss on them might be a tad less likely to send a piece of the face speeding through the shop; but would leave a bigger dent possibly.

[gote]

I disagree Kozzy. You forget inertia and that an anvil is a solid chunk that is not as elastic as the stand.

[Kozzy]

7 hours ago, gote said:

I disagree Kozzy. You forget inertia and that an anvil is a solid chunk that is not as elastic as the stand.

I didn't forget inertia..the point was that the stand/mounting system has a lot more to do with heavy usability than simply mass of the anvil.  For example, set a 3" hardened round bar on end on good solid base material and you probably wouldn't hesitate to use a sledge on it because that energy is transferred solidly.  You might get some bounce due to the transitions to the base material but the fact that the "anvil" weighs only 60 pounds at 30" long wouldn't really affect the blow-taking ability.  Hence, mounting takes precedence over mass.  

Sure there are some benefits to larger overall mass but the original question was about working with heavier blows on smaller anvils--and I simply wanted to note that mass of the anvil itself wasn't as critical as other aspects of the system.  Mass covers up for other shortcomings of the system but is not the be-all-end-all deciding factor about whether heavy work can be done.

Secondarily, smaller anvils might mushroom under huge blows or similar but again, that is about anvil construction and not strictly a mass issue.  

[stan]

I assume the damage we are talking about here is sway, not chipping or deforming of edges which could happen to any size anvil. Sway would more likely result from heavy hammering like strikers and not always large stock,   rather normal hammering by one man. Anvil design may also play a part for example those having a relatively soft wrought iron base. So the relationship between anvil weight and hammer weight needs to be considered more than stock size.

[ThomasPowers]

I have an anvil with very little sway but missing the entire heel, (Powell).  I also have a William Foster missing the heel and 90+% of the residual face. And a Vulcan with a broken off horn.---More types of damage than edge chipping and sway are possible.

[stan]

That's true Thomas,I didn`t consider that level of damage. Heavy hammer is to blame and when striking with large hammers is involve  damage is more likely, but isn`t this what anvils were made for?

[Marc1]

2:100 is the ratio that comes up from time to time when people talk about it, but the subject is so rubbery and there are so many considerations that 2:100 is just a number really.

And when folks get technical about this, the sky is the limit. I once heard a guy saying that he had fixed his anvil so well to the ground that the earth was now part of his anvil ... and one can elaborate further if wanted.

I think that 2:100 is a good rule of thumb and that when it comes to anvils, size does matter.

[ThomasPowers]

Well if he is on the precambrian shield....

[JHCC]

13 hours ago, ThomasPowers said:

Well if he is on the precambrian shield....

That would rock!

[Donnie]

Stock size vs. anvil size?.......Get it HOT.....Let the fire, do most of the work.

[ThomasPowers]

JHCC: but so many people take it for granite...

[JHCC]

20 hours ago, Kozzy said:

I didn't forget inertia..the point was that the stand/mounting system has a lot more to do with heavy usability than simply mass of the anvil.  For example, set a 3" hardened round bar on end on good solid base material and you probably wouldn't hesitate to use a sledge on it because that energy is transferred solidly.  You might get some bounce due to the transitions to the base material but the fact that the "anvil" weighs only 60 pounds at 30" long wouldn't really affect the blow-taking ability.  Hence, mounting takes precedence over mass.  

Sure there are some benefits to larger overall mass but the original question was about working with heavier blows on smaller anvils--and I simply wanted to note that mass of the anvil itself wasn't as critical as other aspects of the system.  Mass covers up for other shortcomings of the system but is not the be-all-end-all deciding factor about whether heavy work can be done.

Secondarily, smaller anvils might mushroom under huge blows or similar but again, that is about anvil construction and not strictly a mass issue.  

Getting back to the original subject, don't forget that a lighter-duty post vise can take hits that would smash the mechanism of a heavy machinist's vise, but neither will do well if mounted insecurely. Again, it's the combination of mass and mounting.

[ThomasPowers]

and material!

[JHCC]

MMM....

[gote]

We are talking about dynamics and deforming the stock. When we hit the anvil, a compression wave travels downwards (and sideways depending upon the shape of the anvil.) It take some time - even if very short before the wave hits the bottom of the anvil and even more until it hits the floor. The deformation of the stock is a very brief thing. The contact surface between hammer and stock will not travel down with the speed of sound but the travelled way is very short so I think that the deformation of the stock will usually be over when the wave hits the floor. With a good sized anvil, it will be over when the wave hits the stand. What happens to the shock wave after deformation is over is of no consequence to the amount of deformation you have in the stock.

We need to keep some things apart here. Rebound is a good way to determine the quality of the steel in the anvil but when we are smithing we do not want any rebound. We want the energy in the moving hammer head to be mostly absorbed as deformation of the stock. If that shall happen,  the anvil surface should move as little as possible under the impact. That is;  the used part of the anvil should have as much inertia (=mass) as possible. This is why London pattern anvils have a sweet spot. This is where there is most mass under the hammer. If the stand shall have any appreciably influence on mass under the hammer it needs to be of a similar material and the same cross section as the waist of the anvil andt hat under the waist with no sound dampening material between. I have yet to see the stand that conforms to that requirement. All are substantially more flexible than the anvil and have less mass. The closest we get is when we use pieces standing up as a fork lift tine or a railroad rail - or a Brazeal anvil. These make best use of the mass by putting it all under the hammer.

To get into the original question, I think that it depends not only on the size of the stock but also on how hot it is and of what material it is. I think we all adjust the weight of the hammer to these parmeters. Then the anvil should have so much inertia under the hammer that its upper surface does not move downwards appreciably and that brings us back to the original question. Since I use Swedish cast steel anvils I do not expect any damage as long as I have the stock under the hammer when I hit.

 

 

[Marc1]

20 minutes ago, gote said:

To get into the original question, I think that it depends not only on the size of the stock but also on how hot it is and of what material it is. I think we all adjust the weight of the hammer to these parameters. Then the anvil should have so much inertia under the hammer that its upper surface does not move downwards appreciably and that brings us back to the original question.

I was waiting for this. Stock size vs anvil size is missing the hammer size. 

Since one changes the hammer according to the stock and according to what one wants to make, and most of the time the anvil remains the same, in the end it is hammer size vs anvil.

After all if you have a 25k anvil and you place a 200mm universal beam on it, as long as you hit it with a one kilo hammer you have no problems. Try to forge the beam with a 10 kilo hammer and you will see some damage somewhere. So it is the hammer and not the stock that needs to be in proportion. Sure the stock is usually proportional to the hammer but not always. 

Which brings me to a side question ... is there such thing as an anvil that is too big? 

[ThomasPowers]

As I may switch around between different sized anvils during a single project I would say that some anvils have better features than others for certain jobs---my 515# anvil has a very very thick heel  my 91# A&H has a heel that is very thin I have moved from one to the other when I needed to switch from working down a handle to drawing out tines.

[Marc1]

Sure ... I was thinking more in the original question, anvil vs stock size. 

Let's say you have just one size anvil. Say a 90 lb one. 

You can work any size stock you want up to a point. Say probably 1" square. Why? not because of the stock but because of the size hammer you need to move it effectively. 

If you take a 4" square bar on a 90 lb anvil, and work it with a 3 lb hammer, you will probably be there a long time but there will be no damage to the anvil, in fact the anvil will be safer if you have 4" stock on it than if you have 1/2" stock on it since the mass of the stock ads to the mass of the anvil combined to form the static mass so to speak, as opposed to the moving mass of the hammer that does all the work or the damage for argument sake.

Take an 8lb hammer to it, if you can swing that, and you will probably endanger your little anvil. 

I remember having to "fold" the ends of a universal beam to make the end look neater ( I think you call them I beam) I did so with a 5 kg hammer but had no need for an anvil. The beam itself had enough mass to absorb the hammer blows.