Glenn Posted February 3, 2018 Share Posted February 3, 2018 I found the video by Joey van der Steeg/@TechnicusJoe showing rebound of a ball bearing on an anvil. DO NOT TRY THIS AT HOME Quote Link to comment Share on other sites More sharing options...
DavidF Posted February 3, 2018 Share Posted February 3, 2018 That is an incredible video. Thanks for sharing. It certainly debunks the play doh experiment! I was mesmerized and will probably watch this a few hundred times. Quote Link to comment Share on other sites More sharing options...
TechnicusJoe Posted February 3, 2018 Share Posted February 3, 2018 If you are going to post the ball bearing bouncing, rebound video, which is an elastic collision, you should post my other video as well. In the bearing video you have cold steel, hardened if I may add, bouncing from the surfaces, hardened as well. Nor the faces, nor the bearing want to deform, they want to keep their shape. So you get a spring action, and it will keep bouncing, whilst a small % of the rebound is lost to air resistence, sound, heat, etc. . In forging we want inelastic collisions. We swing our hammer, or have the power hammer force the hammer ram down and make the steel move. In those collisions, it is preferable that energy is transfered to push the steel around. 100% efficiency isn't even possible: sound is produced, the steel lights up (that is energy that didn't end up moving the steel), and the hammer, anvil, anvil stand also play a roll in energy absorbtion or transfer. What do we ideally want??? We want the steel to move the most efficiently with each blow (in most cases). So if the hammer is swung and hits the steel, and "drops dead", most of the energy will have gone into moving the steel. If the hammer does anything else, produce more sound, rotates in your hand, smacks back in the palm of your hand, etc. Then some of that energy went to that result, and not focused on the steel. Here are a couple of why questions you may want to think about: Why don't people care about rebound on Power hammers? No one talks about that. If it is such an important role, why only the hand hammer? Why don't people care about the rebound on forge presses? That should move steel more efficienctly, correct? Both a hammer and press apply pressure to the steel. Why don't carpenters care about rebound from their hammers on nails? That should make their work easier, correct? it lifts the hammer back up for them? Why aren't general blacksmithing books addressing how important rebound is? I mean a proper explanation. Not the nonsense that boils down to: "oh it's nice to have an anvil with high rebound (but we fail to give an explanation and only address it subjectively.). Why has Fisher & Norris anvils published at least 3 advertisements promoting their anvils with less rebound!!! And I could bring up many more questions, but I'll leave it at this. Don't get me wrong! I'd take a hard hammer and anvil over soft ones any time. They last longer, the face lasts better. Forge scale will pit the faces less, the edges slightly deform over time, or not at all, till the point of breaking. Smiths used to put tool steel, in/on wrought iron where the material has to last a significant amount of time. You can see this on older hammer, anvils, chisels, vises, axes, and many more tools. Do you think they put a steel bit in an axe to make it rebound more when it chops through the wood?? Quote Link to comment Share on other sites More sharing options...
Tennessee Cattleman Posted February 3, 2018 Share Posted February 3, 2018 Great videos on rebound, thanks. Quote Link to comment Share on other sites More sharing options...
ausfire Posted February 3, 2018 Share Posted February 3, 2018 Fingers getting very close to yellow hot steel there! Would have thought the radiant heat at that distance would be uncomfortable. Maybe Joey has work-hardened hands! Quote Link to comment Share on other sites More sharing options...
TechnicusJoe Posted February 3, 2018 Share Posted February 3, 2018 19 hours ago, DavidF said: That is an incredible video. Thanks for sharing. It certainly debunks the play doh experiment! I was mesmerized and will probably watch this a few hundred times. It confirms the play dough experiement. You are not looking at steel being forged. That is totally different from a ball bearing bouncing. With a ball bearing bouncing, there is (practically) no inelastic volume displacement. Whereas with forging hot steel, we displace volume, inelastically, and this takes up energy. Any energy that makes the hammer spin, makes sound, anything else, means, it didn't go into the steel. The same for the anvil, rocking motion of the anvil is energy that didn't go into moving the steel. This even occurs when the anvil is very stightly bolted down to a thick steel stand and that stand bolted down to heavy concrete slab. You can feel the shockwave in the concrete, ground, steel stand and the anvil itself. "So much" for a high rebound anvil focussing the blow onto the steel. Though when the anvil is sufficiently solft, it will deform and absorb the blows. This will plastically deform the anvil. Cold mild steel can dent and deform cold mild steel. A (cold) mild steel anvil easily stands up to hot mild steel and forging tool steels hot on it. Well why bother with the hard face, and forge welding that on then???? Simple, for the same reason they steel an axe. It will last way longer than if it were only iron. Smiths really used to forge a lot, especially at the anvil, if not already with strikers. These tools used to see so much use, that if it were just a soft iron block, which they used to be, they would deform too fast. Not within a day, but in a couple of weeks, the anvils would have to be reshaped again. This is expensive! Especially if the anvil is large! Thus it's benefitial to add a face that will help with wear resistence AND impact resistence. So the anvil face lasts longer, strays true longer and edges that stay longer. Arguably, most smiths today don't need a well heat treated and produced anvil. How many actually spend at least 60% of the time at their anvils, forging? Most stand at the power hammer, press, drill press, workbench or welder. There are only very few left in the world who actually spend most of their time at the anvil and actually produce on there, not just straightening out stock. Quote Link to comment Share on other sites More sharing options...
MotoMike Posted February 4, 2018 Share Posted February 4, 2018 quite enjoyed the videos. Technicus Joe, I am not sure I get what you are saying. If the ball dropped onto the yellow heat bar just stayed there, does it not mean that all it's energy went to moving metal? admittedly not much. if on an iron anvil would the result be the same? are you saying the only reason to have a hard anvil is for it's ability to survive long use? I am perhaps slow on the uptake, or maybe I'm missing some nuance. It is academic for me, just nerdy curiosity. I've been fortunate enough to acquire a family anvil which does have good rebound, has a hard face and is here for the duration no matter. Quote Link to comment Share on other sites More sharing options...
Exo313 Posted February 4, 2018 Share Posted February 4, 2018 3 hours ago, TechnicusJoe said: Arguably, most smiths today don't need a well heat treated and produced anvil. How many actually spend at least 60% of the time at their anvils, forging? You're saying that hardness matters, but only for tool longevity. But by saying this, you're actually saying that deformation of the anvil in fact occurs, and energy is really spent in cold forging the anvil surface using the inferior tools of a red hot struck tool and a hammer. Your argument isn't that this doesn't happen, just that it doesn't happen enough for modern smiths to worry about. Which means, for sake of argument, impact resistance, hardness, and, by extension, the ball bearing rebound test (which is a means of measuring hardness), actually does matter. I think 'throwing the hammer back' is just a colloquial way of expressing the increased return in efficiency in a way that is potentially misleading. Quote Link to comment Share on other sites More sharing options...
DavidF Posted February 4, 2018 Share Posted February 4, 2018 I love this thread. This is exactly what I was interested in hearing and reading about. I am going to go through these more and noodle it for a while. Joe’s videos and feedback provided me with what I wanted to look at more closely. Thank you for taking the time to provide your input. I am sure I will have questions, but I need to spend a little more time digesting everything. Quote Link to comment Share on other sites More sharing options...
DavidF Posted February 4, 2018 Share Posted February 4, 2018 Ok, the second video does confirm the play doh experiment. I wanted to attempt a summary and see if it is correct or if there are additional considerations. 1.) When the stock is heated, the hardened anvil face is less impactful for forging the softer stock (ie. You will have closer results from cast iron or a Vulcan at yellow heat, but will see more difference as the stock cools and hardens). In an extreme scenario, if the below surface is harder than the stock, by heating or otherwise, the majority of the energy will go towards deforming the stock. However, the harder surface will be more efficient for deforming the stock placed against the face. 2.) As the stock becomes harder and either closer to the hardness of the face or maybe even harder than the face, the energy will be transferred less to deforming the stock. And in fact, you could at some point have more energy transferred to the face resulting in undesirable changes to the anvil strike plate and also you will have less result and efficiency for forming the piece 3.) From the above points, a harder face will be more efficient for transforming the piece 4.) In addition to work efficiency in bullet 3, the life of the anvil and usability for a good surface will be increased from a harder material as compared to a softer material over time (although this may not necessarily be noticable for weekend hobbyists since the time for this to be observed may not be observed in the amount of time only weekend work would produce) 5.) This one I am not sure is correct, but I wanted to state this and hear opinions. The rebound theory for returning the hammer to striking position is not true. When the stock is softer than the hammer and anvil, the energy is transferred to deformation of the stock. And as the material hardens, you would not want to forge it anyway, because it will introduce potential issues with the integrity of the steel. Where smiths have experienced the harder anvil being more efficient, it is explained by the decreased energy needed or better deformation of the stock as opposed to rebounding the hammer back to a striking position. From experienced smiths, I definitely hear a consistent opinion that the better rebounding anvil is more efficient, but it is related to the faster deformation of the stock and less strikes required because of this efficiency and the rebound of the hammer is not a benefit when the stock is softer than the hammer and anvil (or the stock is softer than those two surfaces) Are the above 5 points accurate? Again, thanks for the feedback and dialogue. I have been looking into this for several months and this is the best dialogue and examples I have seen on this subject. It is extremely valuable for me to digest and I think others will also benefit tremendously with this repository. There are so many sources on this subject which are not well founded and confusing. For me, this is a definitive answer to this subject and has firmly established my opinion. It is also something I can now reference with confidence that I understand the principles and can talk intelligently (in my case, from a layman’s perspective) about the physics behind how and why to go with one solution versus another. Quote Link to comment Share on other sites More sharing options...
caotropheus Posted February 4, 2018 Share Posted February 4, 2018 The issue of anvil rebound and how important it is pops up in the forum once in a while. Empirically, I noticed that when made my rock breaker chisel anvil (up right position, 120 kg weigh, impact resistant steel, heat treated from the factory, rebound above 90 %) metal would move much faster in comparison with my previous 50 kg lump of steel (I improvised as an anvil, rebound about 60%). So, my empirical conclusion was, better rebound will move metal faster. A more convincing answer may be obtain with a more controled experiment. 1. Lets set two bits of metal (anvil), same steel, same weight , same dimensions, one heat treated to anvil hardness, the other annealed. 2. Lets set drop hammers above those anvils, same weight, same face dimension, same guides, same lubrication, same height from the anvil surface. 3. Lets warm up to the same temperature two bits of steel the same dimensions and mass 4. Lets firmly secure (so more energy is used in forging and not movement) the two bits of steel on the surface of the anvil and lets drop the hammers 10 times at the same time for every drop 5. Let the samples of forged steel cool down and measure with a caliper or even a micrometer deformation 6. Lets repeat the same experiment 10 times 7. Lets make an average of metal deformation for the harden anvil and for the annealed anvil Unfortunately I do not have the resources to do this experiment. It may happen that gains obtained in metal deformation by a good rebound anvil is lost by the blacksmith (anvil not secured enough, metal slide on impact, metal deformation in other area that is not intended, etc). It may happen that anvil rebound is important at human level but at the power hammer is not so important. And the discussion can go on and on and on... Quote Link to comment Share on other sites More sharing options...
Marc1 Posted February 4, 2018 Share Posted February 4, 2018 TJ, you made a few good points in your text but I miss your point in the video. Ball bounces on anvil, a bit less on cold steel, not at all on hot steel ... OK ... the point? Does that mean we can all now buy ASO from China because it does not make any difference anyway? Not a novel topic either. There is a recent youtube video stating that anvil bounce is horse etc Quote Why don't people care about rebound on Power hammers? No one talks about that. If it is such an important role, why only the hand hammer? Why don't people care about the rebound on forge presses? That should move steel more efficienctly, correct? Both a hammer and press apply pressure to the steel. Why don't carpenters care about rebound from their hammers on nails? That should make their work easier, correct? it lifts the hammer back up for them? Why aren't general blacksmithing books addressing how important rebound is? I mean a proper explanation. Not the nonsense that boils down to: "oh it's nice to have an anvil with high rebound (but we fail to give an explanation and only address it subjectively.). Why has Fisher & Norris anvils published at least 3 advertisements promoting their anvils with less rebound!!! Rebound on an anvil is important because it saves the Blacksmith's energy that is limited. Good anvil you work through the day. Bad anvil you get a sore arm at best. Any blacksmith can tell you that. And subjective explanations are all that is needed. It is for the armchair experts to make it 'scientific' Rebound on a power hammer anvil? Saves energy too, but the amount is so small and the energy of the power hammer so excessive that it is irrelevant. Rather obvious. The comment about carpenter hammer is a joke of course and I will not address it. Point 4? see point 1. Point 5? Only the marketing department at F&N can answer that. I suggest a phone call. Quote Link to comment Share on other sites More sharing options...
DavidF Posted February 4, 2018 Share Posted February 4, 2018 I love cao’s idea. I lack the equipment to do this as well. But I think we understand the answers based on the 2nd video. You can actually see the ball deforming the hot piece when it is first heated. As it cools, you start to see the bounce and I can’t observe deformation from any of the cooler strikes. Marc, the point with hot steel, cooler steel, and no steel is that the softer the stock, the more energy goes to deforming the stock. As it cools, less energy goes to deforming the stock and you see the energy going into rebound, sound, light, etc For the comment on Blacksmith’s energy, the point is that more energy is transferred towards the result of deforming the stock and the hammer rebound is non existent or negligible, although it does increase as the stock cools. To me, the carpenter comment is relevant. The energy deform different material, by driving the nail into,the softer wood medium. It is an exaggerated illustration of where the energy is transferred. A very good example for someone like me. For F&N, I agree there is something to be said for the marketing minds. I don’t think it is a great point since based on this thread, I would believe the harder face will decrease the overall work because it provides more energy to deforming the stock. It may be a minimal difference when the stock is first heated, but it should definitely be measurable once the stock is cooling and the energy is going into other areas like rebound from the stock, and most importantly, the energy that can be affecting a less hard face. i wanted to share my thoughts based on the results of the video and the theories explained. I hope I am “getting” it. But I do fall under the category of an arm chair quarterback that is trying to understand theories and improve my practices as a hobbyist. Shoot, I should have had a beer in hand to craft this response. I am a novice arm chair quarterback at best, but working at improving there as well Quote Link to comment Share on other sites More sharing options...
Marc1 Posted February 4, 2018 Share Posted February 4, 2018 Ferre ... I heard this argument before. All the blacksmith that talk about rebound on an anvil don't know what they are talking about.. Rebound is useless because you hit hot steel so there is no rebound right? What's the point? The argument is so moot that it is not worth debating. It just makes for good internet argumentation ... once again. And it will no doubt be resurrected in a few years... or decades? Meantime everyone that buys an anvil will continue to test it with a ball bearing and well advised to do so. For the supporters of no bounce does not matter, save some money and buy a chinese ASO. They go for real cheap at your corner hardware store. Quote Link to comment Share on other sites More sharing options...
basher Posted February 4, 2018 Share Posted February 4, 2018 I think its more akin to wine tasting .....line up 4 blocks of identical looking material, hardened steel, unhardened steel, mild steel and cast iron. get people to forge on them (no hammer bouncing) and see which they prefer....with wine a lot of it is about the purchase experience (preset disposition of the qualities ) not taste.....I think its probably the same with anvils. I have hard and soft anvils cast steel ,forge welded and mild steel lumps, they all forge just fine. I like some more than others.... Quote Link to comment Share on other sites More sharing options...
Marc1 Posted February 4, 2018 Share Posted February 4, 2018 Wine tasting simile .... I suppose you are right, good illustration. My father in law used to drink cask wine and kept the red wine in the fridge and added soda water to it in the glass, and wanted me to drink with him ... After all once it is in the stomach it's all the same ... hopefully no rebound ... Ha ha ... not very technical but there is more than personal taste to a good anvil. It would be interesting to have a row of different anvils covered with canvas to make them all the same and with the face uncovered. Have a few experienced blacksmith try them one after the other and let them tell their 'feelings' free of bias from knowing the brand of the anvil used Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted February 6, 2018 Share Posted February 6, 2018 Having forged on a cast iron anvil that would deform UNDER orange hot spring steel; I can say a hard faced anvil is a lot more efficient! How do you judge the hardness of an anvil face? Well you can use a scleroscope, which measure the REBOUND off a surface and converts it to hardness. This is a scientific instrument used for around 100 years so far. Funny that a DIY version can be made using a clear tube with a scale attached and a ball bearing... As for powerhammers: most of the many posts on them deal with the ratio of falling weight with anvil weight and the efficiency. It is a given that the face of the dies are hard enough to have an elastic collision otherwise the efficiency graphs produced through studies are meaningless. There are discussions on hardness vs spalling out there. Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted February 6, 2018 Share Posted February 6, 2018 Maybe I'm missing something but it doesn't seem to be that complicated to me. Regardless of where the energy goes, an anvil that has a 60% rebound is losing 40% of the energy directed at it to something(s). An anvil with 90% rebound is only losing 10% energy. Whether the steel on the anvil is hot or cold, that same amount of energy is lost by each respective anvil (and mount) every blow of the hammer. Of course the hammer or ball bearing won't bounce high or at all with steel in its elastic state. That's the point. We want as much energy as possible to be used in moving the hot steel. An anvil/stand combo that absorbs 40% of the energy directed at it still absorbs that same percentage of energy whether the steel is hot or cold. When it's cold some of that remaining energy goes into bouncing the hammer off the surface. Instead of thinking of it in terms of how much force is pushing back on the steel think of it in terms of how much force you are losing with each strike. A 30% difference in energy absorbed will make a difference in the number of strikes or the force of those strikes required to move the same amount of the same alloy of steel at the same temperature. It's just plain physics. On 2/3/2018 at 5:18 PM, TechnicusJoe said: These tools used to see so much use, that if it were just a soft iron block, which they used to be, they would deform too fast. Not within a day, but in a couple of weeks, the anvils would have to be reshaped again. By definition that means more of the force of the hammer blows is going into deformation of the anvil made of soft iron than with hardened steel. Again, that's force lost to the anvil system that could have been going into deforming the hot steel on the anvil. The result is more or harder strikes required to move the same amount of steel. There's really no getting around it, but for us casual smiths or those mainly using power hammers and presses this may not be much of a real issue. If I were working as a smith 8 hours a day or more and my income depended on it I'd definitely want the anvil and mount that wasted as little of my energy as possible. Quote Link to comment Share on other sites More sharing options...
MC Hammer Posted February 7, 2018 Share Posted February 7, 2018 Ok, so I liked the videos a lot because the whole rebound premise that it bounces the hammer back and reduces fatigue never made sense to me really. The only time I've had the hammer bounce back is when I miss the hot metal or I'm pounding on something small and and narrow with the hammer head making partial contact with the anvil face on either side. I think when we experience less fatigue with the harder faced anvil because it allows us to move metal better as some have already said. It also makes perfect sense that blacksmiths wanted hard steel so that the anvil lasts longer. I think when you were hammering to feed your family, you wanted to be sure your investment in an anvil and tools was a good one. They'd spend all day everyday at that anvil so it had to be worth what they paid for it. I noticed a huge difference when I started forging on my Trenton vs. the ASO I was using before. I could definitely forge longer and moved way more metal. Of course the anvil was 100 lbs more in weight and mounted on a big heavy stump, but I used that same stump with the ASO so the harder anvil had to have something to do with it. Maybe we just overthink things sometimes missing the simple reason that they wanted a durable surface that wouldn't sway and mushroom. This makes me wonder also if it was the reason they switched to a solid plate of tool steel welded to the face vs. the plates welded in sections that we see with the older anvils? They knew the multiple plate welds tend to get sway in them more so than the solid plate would. So........they were looking for durability and if the solid plate gave them more hammer time (I couldn't resist saying that) with far less risk of sway, then they were all for it. It seems the smith was always looking for a more durable anvil and not seeking rebound as a matter of saving them energy or saving them from fatigue. It's why many of us steer newbies toward the hardest steel objects to start forging if they can't afford an anvil. To my knowledge we suggest sledge hammer heads, railroad tracks stood up on end, etc. because those are the hardest and most durable things someone without money can find to have a starter anvil. Quote Link to comment Share on other sites More sharing options...
Marc1 Posted February 7, 2018 Share Posted February 7, 2018 The argument that anvil rebound is meaningless because the hammer energy goes all into deforming the hot iron and therefore there is no rebound of the hammer is a nonsense argument. The hammer is only half of the equation when forging. The rebound with a ball bearing when testing an anvil is a TEST. This test is to indicate how much of the force applied to the anvil will be sent back into THE WORK, and how much will be lost into the anvil. The bigger the loss, the less efficient will your hammer blow be, and the more tired you will be at the end of the day. The idea that the more rebound the more will the hammer bounce back is another nonsense. A good quality anvil with a high rebound will not absorb energy whilst you work and all of the hammer energy will go into the work from above with the hammer and from below with the anvil and no, your hammer will not bounce back unless you miss. The "rebound-means-nothing" brigade fails to see the other half of the equation when forging. But I said this before. it's a moot argument not worth debating. Just a trolling exercise. PS If you need an illustration imagine to set your forging press die on a one inch thick rubber mat and start forging. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted February 7, 2018 Share Posted February 7, 2018 it's all down to elastic and inelastic collisions and the factors that modify them! For gedanken experiments consider forging on jello or on an anvil mounted on a platform supported by springs or an extremely small anvil. (and note if your anvil is large enough having it on a springy base isn't that much of an issue, it will resist moving when the hammer strikes enough to forge well---if you don't believe that remember the earth is mounted on a springy system...) Quote Link to comment Share on other sites More sharing options...
Marc1 Posted February 7, 2018 Share Posted February 7, 2018 Mm ... forging on gelly ... too much spatter! Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted February 7, 2018 Share Posted February 7, 2018 You should have seen the first time I was trying out a Victorian conjecture on how Wootz was made by trying to forge weld thin high grade cast iron between mild steel plates. The splash was *epic* and the balls of molten cast iron would arc out glowing till they decarbed enough and then they would burst into "high carbon burning steel sparks". I'd repeat the experiment save for the foolish danger of it...ah to be young and immortal again...(and the T is NOT a typo!) It did not replicate the structures of Wootz. (this happened a couple of decades before Pendray and Verhoeven's work) Quote Link to comment Share on other sites More sharing options...
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