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I Forge Iron

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I've always looked at your experiences with your dad as awesome. We all aren't that fortunate to be so blessed. I suppose if I had chosen to be a pilot, I would have similar stories to pass on. In lieu of that I follow your lead and pass on those stories from those who have Influenced my life, as your dad has you.

23 hours ago, Frosty said:

You just make iron move, no need to analyze things you aren't doing at the time.

Come on, thats a statement I would not expect from you. 

To be clear, and this has nothing to do with pro, part timer, or hobbiest, when you spend enough time doing anything, certain functions are done by rote. If you are making say a leaf you dont have to take the time to wonder what is step 1? Should I do this next? You know that without conscious thought. If you see a particular type of vein in your minds eye, you don't have to stop and take the time to wonder which veining tool do i need to create this effect, you just, without conscious thought, reach for the proper tool to get the job done. The more details that fall into this category, the more your conscious mind can focuse on such things as fine tuning design details, forging to dimension, evolving final shapes because your mind is totally focused on the movement of the iron, no longer wondering where its going to end up because I might hit it too hard or not hard enough. Im here to tell you, that's a grand moment  to be lost in. So thanks for your statement. Its not often I discuss this aspect of forging. 

23 hours ago, Frosty said:

About not noticing the anvil returning the blow's energy from below. Does your work not flatten on the bottom side against the anvil? 

Of course. And if you want to think your anvil is adding work, well thats OK. I just happen to believe I'm the one supplying the work.  The bottom does flatten, and thank goodness for the anvil mass to not move. Thank goodness for a hard face on my anvil so I don't have to dress out dings. 

Try this. Instead of dropping a steel ball on your anvil face and checking rebound, get a forging heat(yellow) on a piece of 1/2"x1". Drop your steel ball on it. Notice there is no, or very little rebound. The force is applied, all things considered, completely to the work.

This brings up another aspect of hammer control. Not where you hit it, but how hard do i hit it. I believe  that the most efficient blow means applying the minimal energy needed to get the job done, no more no less. If I apply whats needed, I get no rebound, too much and I will get rebound. This is basic physics, I believe. This brings us up to our debate. This is where rebound matters. Certainly hardness affects this.

 Heres the real question. We do not live in a world of perpetual motion. Ain't nothing for free. So, if I add more force than needed, is the extra energy added plus the "Armstrong" energy to raise the hammer, more efficient than using only the energy needed with zero rebound and only "armstrong"? So ill answer the whole rebound question with a question. "How many angels can you fit on the head of a pin? Will more fit if the pinhead is harden'd?  

Lol, in that "lost in the moment" moment and completely subconscious,  I'm sure I apply only the needed force to get the job done, I just don't want to overwork my poor anvil forcing it to forge(apply work) to the bottom of my hot iron.  


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All I know is that today, forging a box blade scarifer out of 5/8 thick steel, at high yellow heat. When I would hit it the steel rebounded about an inch, even on my Vulcan anvil. Hitting on just one side, both sides upset, so to me the anvil was applying some upward force. When I switched to the Hay Budden, I got even more rebound. The one on the left is what I started with. Took me about 45 min. to shape it so I can weld on the tooth. The last step will be to narrow up the width with the plasma cutter.


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Again, it's my opinion that what you have seen is what I would expect. If you use only the needed force to get that hammer blow done, you will not get any rebound. If you use more force than needed, you will get rebound. And the hardness of your anvil face or type of steel used in a modern anvil will give more or less rebound. The question I have has to due with effiency. It takes a certain amount of energy(armstrong) to raise my hammer from rest. Rebound will subtract from this. However we don't live in a perpetual motion world. Every action costs energy before any work is done. I don't know if the extra energy in to get rebound vs rebound gained would be a true gain or not. I choose to believe it would be an actual loss and try to use just the energy needed to max the work on each blow. Lol, this certainly is not a conscious thought process on each blow, but when I work, I'd say that's my goal.

As for whether an anvil does work or not, again I only state my opinion. I suspect if both these points were taken to a college physics 101 class they would answer this quickly and produce the needed formula to back it up. I look at it that the anvil does no actual work. Iron at a forging heat is plastic. My hammer applies the force and the plastic steel follows the path of least resistance. Thus an edge to edge blow makes an offset on two sides. I respect all views and accept both yours and mine as an opinion from we who are a long way from physics 101. It would be cool to hear from someone who is more familiar with actual physics.

I thought I'd add one more thing. I created my own journeyman process back in the day. I made myself available to any smith who needed help. All I wanted was a place to stay and, perhaps, travel and food. It was not steady work, it was specifically on a per job basis. All these jobs were forgework, no fab, no welding, just forgework.It was a great learning time! I worked on many anvil brands and anvil patterns. I've never been into brands and patterns, so I only know I got a wide amount of experience on many anvils. When working on these anvils, no single brand or pattern jumped out at me and made it clear that I just had to have one like that one. It would without a doubt enhance my forge work. If it had, without question, I would have moved heaven and earth to have one in my shop. This time in my journey prolly is the basis for my beliefs on rebound.  

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Newton's third law . . . action / reaction.
I think the college 101 physics class would use this law.
If you sit in a chair, your body will exert force on the chair (from above),-and the chair will exert the same force on your body (from below).
In our case, a piece of steel between a hammer and an anvil will be hit by two forces;-one from the hammer and one from the anvil according to Newton.
If this has anything to do with anvil hardness,-I don't know. Let the 101 physics figure it out.

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You're trying too hard Anvil and talking yourself into mazes trying to justify a mere difference of opinion. Lighten up will ya? If we get away from one anvil vs. another and discuss where our minds are while working the iron we're on common ground. I've driven plenty of people here nuts describing how working at the anvil is meditative, very zen to me. I don't think about what to do to get the steel to go where I want it, I just direct the steel. WITH A HAMMER! :D Once I'm in the zone I envision the plastic flow of the metal in my minds eye and my subconscious determines how far and which direction before the hammer rises. My information comes mostly through my tong(holding) hand, ears and hammer hand, my eyes are least but measure closest. I don't tap the anvil, I own the rhythm, oh okay I compromise with the  current state of the work. If the hammer rebounds from the work I'm planishing or the work is ready for the fire. I can lift my own hammer and have never claimed a bouncing hammer is any use.

I pay attention to what my tools and the work tell me, it lets me get the most from both. Probably the best example most folks will recognize is a skill saw. You can hear when: it's spinning free, it starts to cut, is taking a working load, is bogging down, or binds.  Power tools speak loudest but they all talk in use if you care to learn their language and listen. 

For example I determine when it's time to return the work to the fire by how it sounds more than works or looks, depending on the process of course. 

No, beyond being resistance to movement the anvil just sits there. In itself it does no work. If you locate a place I've said they do, I'll eat the words publicly. Even dropping one on Wile-E requires someone to get the anvil in position. I've said many times tools are just highly refined dirt without a human.

No, what a hard anvil does is REFLECT the energy applied through the anvil back to the face. In the same manner tapping one side of a pool of water sends waves across which then reflect and return some of the energy. Not all, certainly not. An appreciable amount? Oh yeah. 

Inelastic collision is increased the harder the materials. iron/steel Being squeezed between two inelastic objects is what blacksmithing is. 

I'll put money on the fact that you're more than in tune with your tools notice but you don't pay attention because it doesn't matter to you. I know I can tell which of my anvils I'm striking by sound and feel if not work accomplished. I'll have to think up a blindfold test that won't have anybody hitting the anvil rather than the test coupon. 

The difference between effective energy return (depth of rebound) or wear resistance is so closely related I'd hate to live on the difference. You're not wrong, other than it being the main reason for steel faceplates. You're just the tiniest smidge less right than I am.:P

Frosty The Lucky.


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Good post, Frosty and you hit it dead center, with no rebound from me, you might say.  ;) You got it. I don't think of the physics whilst working or even at any other times. However this thread meandered into physics is what happens when you have too much time on your hands after working too long. If I remember correctly, I think it took me two semesters to get thru the first semester of physics 101.  Far better to heat it and beat it and leave the rest to others. When I watch a piece of hot iron move under my hammer, it's as fascinating to me today as the first time it happened. 





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I debated on adding to this, but in for a dollar etc. 

The problem with this discussion is that we all based this on our memory, experience and opinion. I'm a prime offender here. We did not check for physics definitions. I apologise for not since my opinions caused the debate. Last night I did just that. If you are interested I suggest doing a Google search for:

"What is the definition of work"

This brought up the usual number of one paragraph definitions. Note many were from Britannica and Webster's, not opinions.

Here's what it did for me.

1) it reaffirmed my opinion on what a rebound test does.

2) it reaffirmed that at the very least one of if not the only primary reason for heat treating an anvil is to minimize wear.

3) work done by an anvil. This one is the main reason I checked definitions. I remembered vaguely that distance was part of the definition of work, but could not for the life of me figure just how. It's pretty straight forward. 

D*force=Work. Distance your hammer/ball drops times force applied by hammer/ball equals work done. The anvil doesn't move. Therefore it does no work on hot iron. The hammer drops, applies force and does work on  the hot iron in all directions. The hot iron moves in the paths of least resistance.

I couldn't find anything on this quick 30 minute search that gave any hints if the rebound of an anvil affects work. I suspect this makes the equation very complex and beyond my understanding.  That's why I stated #2 above as I did. 

Again thanks to all for the discussion. Anytime a discussion makes me think is worth it.


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I don't think of physics at the anvil but I pay attention to what works and given time try to figure out why. While I'm aware of the the physics calculating it doesn't enter in. Some knowledge of the hows and whys can be very useful like: Force always takes the most direct path. This tid bit really shows when turning scrolls and rings on the anvil face. That can seem really complicated but once you recognize what's happening it actually makes things easier.

It's not about numbers and mathematical symbology, it's about having a working handle on how things work. 

Fun discussion, thanks for being a player Anvil.

Frosty The Lucky.


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On 10/4/2020 at 2:18 PM, Frosty said:

About not noticing the anvil returning the blow's energy from below.

Does the anvil actually 'hammer back' from below?  Or is this just a version of explaining transfer of force like "If you push on a wall with your hand, the wall is pushing back with equal force upon your hand, therefore the wall does not move"?

Since momentum has to be conserved from the collision of hammer to anvil, then the anvil would move, albeit not much, if it were not firmly affixed to the stand and the stand to the floor. Any fault in that continuous connection would allow movement and loss of momentum to the receiving end of the hammer blow. The greater the mass (the more immovable the mass) the more energy is transferred back to the hammer.  Now that I am writing this out, I think this is where your 'returning blow' reference is coming from, yes?. Place a piece of work between hammer, with momentum, and anvil, which will not change momentum, and the enrgy from the velocity and weight of the hammer is transferred to the work. Bug, meet windshield.

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I don't think of the physics when working either. When wanting to accomplish something, I subconsciously due to repetition know how hard and where I need to hit it to get it done. And yet the OP is often asked as are the other two. So sometimes it's fun and worth dealing with. It led me to reviewing forgotten physics. That's good. 

NS, my experience is different. To repeat, I did a self imposed journeyman ship. I spent a 6-7 year period where I worked in a number of shops , never less than a week and only once for 6 weeks. I learned a lot in a working situation from different Smith's about many things. I worked on many different anvils both pattern and make. From PW's to Budn's and Kowalsa's to a number of other unknown or forgotten modern cast steel anvils. I certainly noticed differences in both pattern and make, but none of them jumped out at me as a must have for any reason. If it had, no matter the price, I'd have it in my shop. That's my experience. Yup, different than some. So I've a tendency to put make and pattern into the catagory of ford vs chevy. I don't get in those um, er, debates either.  ;) Besides I know beyond a doubt that Willy's beats Ford's and Chevies hands down! I will add, again,. ;) That I spent ~20 years as a farrier and my anvil was a modern cast steel Enders farrier pattern anvil. 125#. When I transitioned to "blacksmith" over 30 years ago,

it's benefits as a farrier pattern fell short to the benefits of my PW, then Trenton. Any affects due to rebound or hardness were not a factor.

Hearthstone, no, by the definition of work, an anvil does no work. I'm assuming for simplicity that the connection between anvil and stand and stand to earth is perfect. For my two cents, these two connections are far more important than either pattern or brand.

No doubt new tech makes for more rebound. Also I understand "work" done by hammer on hot iron no matter the anvil. My experience tells me the difference between anvils is not significant especially when considering cost between the two.

One brand did jump out at me and for the negative. I spent a short amount of time in my shop using a ~200# arm & hammer. It may not have been a good representative of arm & hammer brand, but it was a dud! Thus I've never considered any old cast iron composite anvil for my shop of any kind.

Lol, my new shop is close to completion,,, then I can get off this physics kick and get back to plane ole heating and beating.

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Actually even if rigidly mounted it moves. I've seen experimental set ups on microstrains where they were using 4-6" sq stock cantilevered with micro strain gauges on them and just laying a finger on the end of the bar would make the readings zoom.  Way to small to be aware of with our senses; but it does occur.

Also reading up on how the atomic bomb worked they were using explosives to create a compression wave in the fissile materials that would make it more prone to support a fission chain reaction.   So hitting the anvil face should do likewise on a very much smaller scale.   (Been out to the Trinity site twice now, it's a milestone for the "Beware of Geeks Bearing Gifts" philosophy...)

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So you all know, I’m really enjoying this back and forth. Just to add my two cents, think of this as energy conservation. On the ball drop test, you have a known potential energy before the drop (H1 x G x M) and when it peaks out after the redound you have a different level of potential energy (H2 x G x M). H2 (return height) is always less, so energy is going somewhere. Some is lost to air resistance, but those type of losses while be the same for two different anvils. So, the difference between a 90% return and a 70% return on two different anvil is pretty significant energy loss. Whether it heat generation, vibration or material deforestation doesn’t really matter, it’s lost. My thought experiment, is whether that loss remains the same when there is hot steel between the anvil and hammer or not. My expectation, is that the loss is still there, but maybe not to the same degree.

Not trying to spark any arguments, just thought experiments...


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Though that is now making me wonder if some of the meteor strikes are really aliens doing inverse ball bearing tests---We drop the nickel iron anvils onto the LARGE ball from space and see if the impacts cause deforestation....

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"This one probably won't make a good anvil, Captain. Spectroscopy reveals a high iron content, but the elasticity of the collision leads us to deduce that there is a liquid core to the planet that is absorbing a substantial amount of the rebound."

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But the magnetic field is spot on for hardening!  Lets brush off those large sauroids and see if that improves things...

(Actually the earth is rather like a chocolate covered cherry with a solid inner core surrounded by a liquid and enclosed in a solid crust...)

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12 hours ago, ThomasPowers said:

"Deforestation"  I nominate you for the "Best Typo on a Friday" award!  (Probably "deformation").

And I thought he was tying this to global warming--if a butterfly flaps flutters its wings in the Amazon, anvils everywhere can lose rebound.

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Re: ThomasPowers--I know I have to work on my stump mounted anvil.  After a few days of work I have to give it a nudge back into the sweet spot I like.

Re: anvil pushing back--I know there is no active push back from the anvil but when you use the equal force when pushing on a wall example, it sort of comes out that way at the moment of contact, a mere fraction of a second when the direction of momentum changes. No matter how I approached the example it always came back to that.

Re: thought experiment.  I would think that if you have a 30% loss of force impacting the anvil then that loss would be the same but only for the force impacting the anvil, which would be original energy less that impacting and deforming (or deforesting;)) the work.  Which leads to another rabbit hole to go down>>> I have a moderately okay anvil. And we all know when you hammer the work you flatten the top AND the underside where it contacts the anvil.  In the case of my "meh" anvil, the underside of my work never deforms as much as I would think it should.  I always thought it was mainly due the the temperature loss while contacting the anvil.  But, given this thought experiment and discussion I wonder if the loss of energy to deform the work at the anvil surface could also be due to the loss of energy to the anvil.  Therefore, loss of rebound = loss of energy to the anvil = loss of force to deform metal on the lower surface of the work.  The upper surface of the work being less affected by the anvil, more by the hammer's energy and force.

Goods, you are correct, great discussion and not unrelated to the physics of blacksmithing and the original rebound topic of the thread. There has got to be someone on this forum with an advanced degree in physics that could indicate if our layman's use of Newton's laws are anywhere near correct.

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Very cool. Let me add my thoughts these last few daze instead of debating these points. I think it will at least make my beliefs clear and will point out my own questions. I believe it will deal with our debates as well.

First, due to my quick and dirty google research, it brought back from freshman physics the definition of work, types of energy and reference system . I accept this definition of work as the basis of all to come.

W=D*Force.  D is distance of the ball/hammer travels, and Force is potential energy converted to kinetic energy plus any force added by armstrong.

Plane of reference: we create this and for this discussion, we have an x, y and z axis. We define the zero point where the ball or hammer are at rest in the center of the anvil sweet spot.

When the ball is at rest at the sweet spot, there is zero energy in the ball or anvil. 

When we raise the ball/hammer say 18", we have created potential energy in the ball. Anvil energy is zero.

When we drop the ball we create kinetic energy. 

When the ball hits the anvil work is created. One of the measurements of work is "distance". In this case the rebound we get.

Therefore, the ball creates work and applies it to itself, measured by rebound. Nothing added from the anvil 

If we have an anvil made from clay, wood, cast iron, wrought iron, composite anvil, or a contemporary cast steel and all appropriately heat treated, we get a different rebound height. 

Thus and without question the composition of an anvil has a direct affect on the steel ball.

That's a starting point that should satisfy all.  ;)

Now we want to forge a piece of hot steel. So, let's take a piece of half square and we want to forge 1/2"*1/2"*1" to 1/4"*1/2"*2". The kiss principal says we have the tooling to move the hot iron in one direction and done in one blow. Also we simplify this discussion by eliminating many small factors like friction.

Even tho I don't have it, I'm sure there is data out in the metals world that states the amount of work that must be applied to achieve this. It's prolly found in physics 202 and metals properties 101.  ;) If we know how much work it takes, then we can figure the exact force needed in our formula. I suspect these calculations are commonplace in contempory industrial forging at every level. The closer we are to using only the needed force, the more efficient we are.

Thus if we drop our hammer 18", apply the proper force, we get our forging above. Also, when completed, it seems the hammer should have no rebound and since they are at the zero point, the system is back to zero energy. It was all used, no extra. We can only get rebound on the hammer if we add more force than needed to do the job.

So where does the anvil composition come into play? I'm guessing when we figure the needed work to do our forging, there must be a needed calculation to take care of this.

I think the only way for we mortal Smith's can measure this and compare two anvils would be to on each anvil, have the hammer control to do the forging above with no rebound, just do the forging  then make an assumption as to the difference of energy between the two anvils. 

How about that, Frosty, that brings us full circle as to weather your sodofer is more efficient than your trenton. Or my trenton compared to my enders farrier pattern cast steel anvil.  :)

Lol, my experience and my assumption says no appreciable difference. Yours states the opposite. Notice I'm saying no appreciable difference.

If I choose to critique myself in a negative way, I would say I haven't paid attention to reality.

If I choose to critique those who believe the opposite, I could easily say ya gots to have some reason for justifying the huge cost difference.  :)

of course, I'd never do that.  :)

Me being me I choose to believe both conclusions are valid and they both exist in our own personal realities created by our own situation and needs.

so I'll leave it to ford vs chevy and continue to believe that the prime benefit is limiting anvil wear. That means that instead of a PW needing to be refaced every 300 years, perhaps your sodofer might need a reface in 400. We will never know, that's a fact.




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