Mass vs Rebound

[basher]

most anvils and hemmers are made of hard material so that they will last , not because it affects your immediate work on the tool.
I have hammers that are soft and hard and notice no difference between the two , I have also used "proper" anvils and mild steel blocks and again no difference for a given weight (as much as i can tell) .
my current favourite forging hammer is soft (it has moulded its face to a jaunty angle) , and current favourite anvil is hard!.
that many of us are using anvils over 100yrs old is a testimony to how good a hard anvil lasts .

I have found that the mass of the guy swinging the hammer (and how hard he is) has more effect than the anvil .

[Timothy Miller]

The iron doesn't stay in a bright yellow plastic condition so you start getting resistance/rebound as the material cools. Silver and gold are soft at room temp and generally worked in that condition - so is bread dough. I agree with your comments about scale but if cast iron anvils were the epitome then that's what all of us would use.

Im not saying that cast iron anvils are all that great. In fact I dislike them because generally they are ugly and they don't stand up to cold work and missed hammer blows. If you only worked hot on them they work. I agree you start getting more resistance wile the material is getting cold. This is a good time to stop forging and take a heat. What point I am tiring to make is that if the material is significantly softer than your anvil face it makes no difference how much harder the anvil is in relation to it. You are not getting a whole lot of rebound from the hard anvil face thru the soft work assisting you in lifting the hammer. Ideally you want all of the force of the hammer going into work piece not rebounding and propelling the hammer back to you.

[ThomasPowers]

Actually I once used a cast iron anvil in an emergency and found that it was denting under properly hot coil spring---not cold working. It was a 100 kilo anvil purchased because my sole anvil was stolen 3 days before a day long demo at a museum and I had to have an anvil.

After I used it that one time, I put it away and never used it again---a very expensive demo that was and I wish I could have used that ASO as a life jacket for the thieves! (This incident is why I tend to have back-up for everything in my shop now...)

[Nakedanvil - Grant Sarver]

I have found that the mass of the guy swinging the hammer (and how hard he is) has more effect than the anvil .

:lol:

[Nakedanvil - Grant Sarver]

Of course there are degrees of hard and soft. Cast iron is too soft for an anvil and pure wrought is too soft for a hammer. In the old days they went to a lot of trouble to put a steel face on a wrought iron hammer (same with anvils for that matter). Basher, I think your soft hammer is hard enough. Unhardened is still harder than soft material. Hard and soft are just too general. How hard is hard? How soft is soft?

[Mainely,Bob]

When you think about it many of the previous posts are missing one important point;except for the new solid tool steel anvils and the dreaded ASOs none of our anvils are a single homogenous mass. The majority of the anvils we use are 2 part assemblies with a base of softer,less expensive material (CI or WI) intimately mated to a tool steel face.
Keeping that in mind, what happens when that intimate contact of the two materials is compromised? It`s not only the pairing of two different materials that needs to be considered,it`s they manner in which they are joined that plays a rather large part in ending up with a more durable and useful tool. Get that interface wrong or compromise it and a good tool suddenly becomes far less effective and useful.

Another point is that most are missing is appropriate shape is a factor. More than once I have heard the "cone (or pyramid) of impact/influence" referenced. Anything outside of that cone is supposedly marginally influential material when it comes to moving steel and may well be a hindrance to navigation when traveling between the forge and the place you intend to stand while doing the work.
As an example;we know that a RR rail is marginal for use as a forging anvil when used horizontally (used in the position a train would run on it) and yet turning it to a vertical position (as it puts the entire mass of the rail within that cone of impact and under the direct impact of the hammer) changes things for the better. the simple act of changing the orientation of the mass makes it far more useful in forge work and especially knife work.
Without knowing the shape of these heavy pieces of mild steel (or better yet looking at a pic) none of us can give a definitive answer as to their true level of usefulness.

[pkrankow]

There was a world of difference between my cast iron ASO and my Trenton. The difference was not just that the Trenton weighs 100# more. I am sure that the harder face and better fastening and extra weight make for a significant difference in performance.

I have a normalized hammer (I reforged the peen and did not harden it), and it works fine I prefer a harder hammer because it does not need dressed as often.

Phil

[Timothy Miller]

I stand corrected as far as cast iron anvils go. I have a dim memory that when I first started I got my hands on a cast iron anvil and it did deform wile I was forging hot steel. If you can call what I was doing forging at that point. Also cast silversmith stakes are what are called Semi-steel I was told that it was a mixture of tool steel and cast iron. More likely engine blocks and RR track. But for discussion's sake lets say you have an anvil that's Rockwell 35 and one that is 55 both of the same weight and shape. Your hot metal never gets close to this level of hardness. Because you are a perfect smith who never works cold iron. Will the softer anvil be less efficient to work on wile working hot soft steel or iron. I don't think it will make a difference. What do you think.

[pkrankow]

the brinell hardness of common cast iron is between 140-200 which would equate to a Rockwell C 2-23

Chilled cast iron can be up to about Brinell 500 or RC52


Foam rubber, huh?

Phil

http://www.atlasfdry.com/grayiron-hardness.htm
http://www.carbidedepot.com/formulas-hardness.htm

[evfreek]

Hi southshoresmith. Both you and Thomas/HWooldridge may be correct. It is pretty close, anyway. The following reference may be helpful:

http://www.esm.vt.edu/%7Erbatra/pdfpapers/confproceeding1994%28533-537%29.pdf

It gives curves for shear stress of 1151 steel at strain rates associated with hammer forging. At 800C, 18850 psi is shown. At 1000C, 7800 psi is shown. Cast iron has a yield strength of about 20000 psi. If you strike a centered piece of hot steel in the middle of the anvil face, you are in the safe zone. Any cooler, and striking over an edge, especially if the target is thin and provides little shielding, may put you in the danger zone. Alloy steels retain significant strength, and extrapolating to a dull red may give values exceeding the cast iron yield strength. There are no curves for 1045 or 5160, but the latter might be stronger. If you look at old cast iron anvils, they can be in pretty bad shape. The traditional Chinese bread loaf shaped anvils would tend to survive better.

All this exploration gives some suggestions. Work hot. Avoid the edges, if any, when drawing high carbon steel. Use the hammer peen instead.

Actually, surfing around for some forging dynamics papers and combining with some physics can go a long way towards solving the problem that Thomas was asked to pose to a grad student. I am afraid, however, that the typical grad student may have some difficulty making much headway on this problem.

[Timothy Miller]

I remember reading that the traditional cast iron Chinese anvils were more like cast steel than cast iron.

[thingmaker3]

If we do a little thought experiment, we can see that a 5lb block of tool steel will make a much better anvil than 1,000 lb of foam rubber. That's a silly example to show that we can presume hardness is part of the function, not just mass.

Not silly at all!! Foam rubber is very effective at transforming kinetic energy into heat. Cast iron is not as good as foam rubber when transforming kinetic energy to heat, but it is indeed better than steel. This is why cast iron is the material of choice for machine bases and frames - it "absorbs" vibration better than does steel.

[dbrandow]

Remember that a small anvil can be effectively fastened to a very large mass (the Earth) without a whole lot of fuss.

I find that point to be fairly specious. Based on that logic, the anvil itself is irrelevant, considering the relative mass of the anvil and the Earth and you could just as well hammer on the ground. Naturally, of course, that doesn't work, earth has virtually no rebound. Rebound is clearly not just a factor of mass, or even primarily a factor of mass. I'm no physics or chemistry major, but presumably rebound is determined by compressibility/moveability. The more the thing being hit compresses and/or moves, the more energy it absorbs from the blow and thus the less it rebounds. So your point about attaching it solidly is a valid one, but your point about the relative mass of the anvil and the Earth is not. The reason the original blacksmiths used rocks was because they compress less than earth or wood, their other choices. They then switched to iron/steel of increasing size once production techniques allowed them to do so, again, because iron/steel compress even less than rock and is of course far more durable.

[pkrankow]

I find that point to be fairly specious. Based on that logic, the anvil itself is irrelevant, considering the relative mass of the anvil and the Earth and you could just as well hammer on the ground. Naturally, of course, that doesn't work, earth has virtually no rebound. Rebound is clearly not just a factor of mass, or even primarily a factor of mass. I'm no physics or chemistry major, but presumably rebound is determined by compressibility/moveability. The more the thing being hit compresses and/or moves, the more energy it absorbs from the blow and thus the less it rebounds. So your point about attaching it solidly is a valid one, but your point about the relative mass of the anvil and the Earth is not. The reason the original blacksmiths used rocks was because they compress less than earth or wood, their other choices. They then switched to iron/steel of increasing size once production techniques allowed them to do so, again, because iron/steel compress even less than rock and is of course far more durable.

Maybe it is...maybe it is a bit factual...

Take for instance that the traditional proper way to mount an anvil was to bury a hardwood tree with a crotch upside down deep in the shop floor, then build the shop around the stump. The anvil is supposed to he fastened to this stump. That is pretty well fastened to the earth.

A similar means can be done simply burying a timber vertically in the ground, or making a strong tripod and fastening it to the ground via stakes or bolting it to the concrete floor. Making a strong fastening to the Earth is not particularly difficult.

Yes I freely concede there are other modes of movement at play, elasticity in the wood, damping of movement in the soil, the joint of the anvil to stump, the strength of the materials in use, ringing of the tripod, the feet of a tripod sinking or bouncing... All in all I would prefer working on a very well fastened 50# anvil over using a 150# anvil that is sitting free on a log.

I feel my current arrangement is a compromise of a 168# anvil well fastened to about 100# of log that is free to move about. If I had the material and equipment to weld up a tripod that could be staked or bolted down I would. I know that this same anvil sitting loose on the top of a stump is very hard to work on, and will not even stay put under blows from a hand hammer, where it is quite stationary as I have it set up. I am limited also in that the only storage for my equipment is the attached garage, and I must move outside to do any hot work.

Phil

[dbrandow]

Yes I freely concede there are other modes of movement at play, elasticity in the wood, damping of movement in the soil, the joint of the anvil to stump, the strength of the materials in use, ringing of the tripod, the feet of a tripod sinking or bouncing... All in all I would prefer working on a very well fastened 50# anvil over using a 150# anvil that is sitting free on a log.

That's fair. I would certainly concede that any energy that ends up moving the anvil is wasted energy.

That being said, I have a relatively similar setup to you, a 200# anvil fastened to about 100# of log. The advantage, I find, is that I can swivel the anvil about if I need to come at it at an angle that would be inconvenient with the material I'm working.

[Francis Trez Cole]

from what I have seen it is how the anvil is connected to the earth that is the key not the size. Brian Brazeal makes this point very clear try working on his striking anvils and you never go back. I re did my stand for my mousehole forge anvil 127# the anvil needs to be attached to the stand and the stand needs to be attached to the earth there is a noticeable difference.

[bajajoaquin]

If you attach a wooden stump firmly to the ground, is it going to work as well as an anvil that is laying unattached? So there is something at work that is as important as (and perhaps more than) fixing something to the ground. But if we have too many variables, there's no way to isolate the effects of different ones.

So going back to the limited hypothetical, perhaps it needs to be changed, and established as valid, first. would a 100lb block of forklift tine be a better performing anvil than a 100lb block of mild steel in the same shape, with the same attachment?

[HWooldridge]

If you attach a wooden stump firmly to the ground, is it going to work as well as an anvil that is laying unattached? So there is something at work that is as important as (and perhaps more than) fixing something to the ground. But if we have too many variables, there's no way to isolate the effects of different ones. So going back to the limited hypothetical, perhaps it needs to be changed, and established as valid, first. would a 100lb block of forklift tine be a better performing anvil than a 100lb block of mild steel in the same shape, with the same attachment?

Most definitely yes...

[evfreek]

I remember reading that the traditional cast iron Chinese anvils were more like cast steel than cast iron.

Interesting. There is a wide range of cast iron strength levels, depending on processing. Do you have more details?

[clinton]

Rebound is over-rated- put the material between the dies and forge. Plain and simple, rebound does very little when it comes to moving metal

[philip in china]

I remember reading that the traditional cast iron Chinese anvils were more like cast steel than cast iron.

There are, from my experience, 4 types of anvils made in China.

The cast iron ones such as the G****ly sold in USA. So much has been said about these that there is no need to add to the comments.

The loaf of bread shaped anvils. These are fabricated as a box using angle iron and plate and whatever else comes to hand. The face is deliberately domed. They are then filled with steel from a melt. They actually behave surprisingly well and a lot of good work is turned out on them. There is a photo of one of these on another blacksmiting site.

Chinese anvils made for the Chinese market. These are steel and look pretty much like a western anvil. They are OK. Not a Soderfors but entirely adequate for most purposes. They tend to be smallish upto about 50Kg.

Anvils made in China but for export to the west. These are cast out of high specification alloys to western standards. There are at least 2 manufacturers who make their anvils in China and sell them in the west. Many people buy them without realising that they are not Western products.

So you really can't generalise.

[nonjic]

Interesting topic. Regarding steel anvils I was under the impression that all steel has the same modulus of elasticity - regardless of grade. Which logically suggests that a mild steel block will have the same 'rebound' properties as an alloy steel block of steel. Assuming that the yield point of the block is not exceeded.

So could the perceived (or actual?) difference in rebound of a hammer / ball bearing or whatever be down to the microstructure of the steel ? ie tempered martensite provides a better rebound than perlite ? (way outside my understanding now....)

or,. does the heat treated micro structure, and all those lovely alloying elements just improve the mechanical properties of the anvil (abrasion wear resitance, crack propergation resistance, fracture resistance et al ?) - and have nothing to do with its effectiveness as an anvil ?

[evfreek]

Interesting topic. Regarding steel anvils I was under the impression that all steel has the same modulus of elasticity - regardless of grade. Which logically suggests that a mild steel block will have the same 'rebound' properties as an alloy steel block of steel. Assuming that the yield point of the block is not exceeded. ...

That is a huge (and incorrect) assumption when you are bouncing ball bearings off a steel block. A hardened 52100 ball bearing will leave a dimple on a mild steel block when dropped from 1 foot above. Computing the impact force and finding out that it is above the elastic limit is not a trivial problem. There once was a website which told how to do this, but it is now defunct.

[evfreek]

Hi Philip. Thank you for the detailed description of the different types of China made anvils. That is very interesting. Perhaps one of these was what southshoresmith was referring to. Since this topic piqued my curiosity, I started looking around the WWW for information. There actually is quite a lot, much of which seems to have been added in just lee last few years. It seems that this "steel-like" cast iron has been around since 200 BC. The Chinese have learned a lot and forgotten a lot. My Chinese colleagues are not much help from the physics, engineering or metallurgy fields. Snappy one line answers and suspicions about why I am snooping about this stuff. Much better luck from the historians.

If the "bread loaf" anvils are fabricated, why do they have to look like bread? Edges are useful, and junk steel can support some decent radii unlike junk cast iron?

[pkrankow]

Hardening changes the tensile strength of the steel, in fact hardness can be used to gauge strength. Increasing the strength of the material increases its resiliency, the ability to return energy and resist plastic deformation. This is desirable in an anvil.

Actions have an equal and opposite reaction, however all collisions are not created equal. The quality of the collision can change from perfectly sticking (all kinetic energy absorbed by deformation) to perfectly elastic (all kinetic energy returned to the objects) and still satisfy Newton.

Phil