Graham Fredeen

Thanks. I threw it together in a weekend. It was a really quick build. Not sure on exact hour breakdown. Total cost all said and done was about $250-$275, might as well call it an even $300 in case I am forgetting something, which I think is pretty reasonable, all things considered.

Here's my newly completed heat treat furnace, and have yet to see a furnace that is like it or that can do as much. Just put the paint job on it this afternoon. It is digitally controlled with a PID controller, which takes in a temperature reading from a k-type thermocouple and then operates a gas solenoid valve to regulate when the burner is fired to regulate temp. It has about a 40" blade capacity (built it so I can start getting into swords again. I had put aside the long blades until I got a better HT setup). The blades hang vertically into the burn chamber (this is a pretty uniqe design feature that I havent really seen in other furnace designs) which really cuts down on the warping and sagging that can occur when heating and trying to manuver a red hot piece of steel horizontally. And here's the kicker, it will operate at BOTH high temps, for heating blades to critical, AND at low temps for tempering. Ran tests at both 1550 F and at 400F and it operates great. From my initial testing it looks like I can maintain temps within about +/- 10F of the set temp (which is quite good). From the initial test, looks like it produces pretty even heat (from what I could tell by eye) over the entire length of the furnace. It has a pretty awesome rising heat vortex from the way the burner is mounted that distributes heat pretty evenly along the length of the chamber. I've still got to run more tests with it and play around with settings to get it fine tuned, but so far it works great! And now for Pics First up is the Burner manifold. Sidearm burner, solenoid, and the pipe that runs parallel to the burner is the pilot light jet. One of the burner manifold mounted Front view. Control panel (still need to wire in a switch) I'd be happy to answer any questions about the furnace, its design, construction, etc. I'll also try to get some pics of it running when I get a chance. Hope you enjoy Graham

I think the only way you'll be able to achieve that result would be with a baking lacquer. I've never used any myself, but I have seen it used by Ed Caffery on some of his damascus to give some wild colors (including green). Brownells makes some, though I don't know if they have your particular color (looks like they cary more camo based colors for firearms), but somebody makes green. The baking lacquers bake on at about 300-350 F so they won't ruin the temper of the blade. I also can't really comment much on the durability of the coating, it is suppose to be "scratch resistant" and I know it would hold up better than paint, but I'd imagine it is still limited. Im sure if you research baking lacquers you'll be able to determine if they are what you are after. Graham

The HT of a blade should follow its intended function. Since this is a small blade and a skinner (not going to be put through heavy abuse like a brush knife/heavy chopper) there is not much of a need to differentially temper the blade (tempering the spine more than the edge) by heating the spine with a torch until a blue color, and the straw color runs out close to the edge or heating a large piece of steel and setting the spine on that until the temper colors run to the edge. My recomendation for tempering in this case is to use the oven. Do you know the particular steel you used for the blade? That will effect times and temp. For most blade steels in small to medium knives I'd recomend 375 - 400 F, running at least 2 separate temper cycles of a minimum of an hour a piece. 3, 2 hour cycles being quite good. Depending on the steel, you might have to temper higher or longer (higher carbon steels that harden deeper, steels with alloying elements that effect carbon diffusion rates etc.) check the edge with an edge flex test to determine if the tempering temp was high enough. If you wanted to differentially temper the spine, I recomend tempering the entire knife in the oven at slightly lower temperature first (350-375F), then after that pull the spine. Keep the edge cool (submerge in water) and then heat the spine with the torch (to about a deep blue color). You'll want to repeat the torch heat at least 3 times.

There are a few different options to avoid/reduce scaling and decarb durring HT. One common method is to use stainless steel foil to make a pouch to put the blade in. You can purge the pouch with an inert gas or, stick in some thing combustiable in (like a bit of some paper) to remove/consume the oxygen in the pouch. Also, If you use a high temp salt pot for HT you wont have to really worry about scaling or decarb. Since the blade is heated in molten salt, it is never exposed to oxygen durring heating to cause any scaling or decarb. That or a fancy electric HT oven that is perged with an inert gas. However, since this was your main concern, there is a specific coating designed especially for heat treating. Its called Turco pretreat. You dip the blade into the turco, let it dry, then proceed with with the HT. The turco protects the blade from any contact with oxygen. I don't know its max working temp, but I know it works in the ranges for HT for blade steels. After the HT you can either clean off the turco with a bit of sand paper or with some type of solvents. I havent ever personally used it so I cant give you all the details, but I know its out there. I think awhile back I remember Rich Hale mentioned that he uses it and can probably give some more details. You can get a quart of it for about $40 from knifeandgun.com I havent heard of metalbrite or the other.

I agree with starting small for the first billet, if that is a success work up to the bigger billets. I think the bigest thing for successful welding is to clean and prep the starting material correctly. Grind off all mill scale/ rust/ pits, etc from all mating surfaces. Keep the grind lines going across the stock and not down the length, this will help the flux to escape by giving it a shorter path to take. Make sure that the stock is flat (or slightly convex, but not concave. If its concave you will risk traping flux inbetween the layers and having inclusions). There are all kinds of great steels to use for pattern welding, but to start keep them simple (you could pick something from the high and mid range of the 10xx series for example). Like Thomas said, probably want to avoid Cr and Ni alloys on your first billet until you get the process down. As far as simple patterns for the blade, there are quite a few that are easy to do. You could do a simple random pattern by taking a hammer and working the billet unevenly to shift the layers randomly (knock some dents in it, maybe use a ball pein for a bit, etc). You can also do a simple twist pattern by squaring up the billet and giving it a twist over its length or in sections. And ladder patterns are easy to do as well. After the billet has been folded to desired layer count and trued up to a good stock size, take and angle grinder with a rounded off grinding wheel and grind grooves across the billet, then forge into a blade. This exposes different layers deeper in the billet and creates a pattern that resembles the rungs of a ladder. You can modify this to do things like a serpentine ladder pattern (cut the grooves only to the middle of the billet and offset the grooves on both sides of the billet, creates a zig zag/ winding pattern down the blade). Rain drop patterns are also easy to do, just take the billet to the drill press and drill some shallow holes all over the billet.

If you weld your blade billet to a handle or use a long piece of stock you can stick it between your legs and use your inner theighs to hold the stock while you cut it with the hand held hot cut (hatchet). Just make sure that the stock/handle is long enough to not heat up, since as you can imagine a hot piece of steel between your legs could get uncomfortable really fast. You might be able to do it with tongs as well, but thats even trickier and I probably wouldn't want to try it myself. It takes some practice but it works when you don't have an extra pair of hands available. That or get a vice and clamp the hatchet head (or forge up a designated hot cut) in the vice and use it that way (probably the best bet). You could also make an anvil hold down tool, but you'd need a hardie hole for that. Also, an angle grinder with cut off wheels is great for cutting up stock. It can go faster than hot cutting (depending on what exactly you are doing), doesnt distort the stock, and is much cleaner than trying to torch cut things. If you don't already have one and need a cheap angle grinder check if there is a harbor freight store near you. They can often be had for about $20 (some times cheaper if you catch them on sale). I have had mine for about 3 years now and have put it through some serious work and it still keeps kicking (original set of brushes too). Graham

I tried to keep the original post fairly short so I gave the condensed version. If you run into any more snags or need any additional information please feel free to let me know. I work a lot with 5160 and have the HT down pretty well and would be happy to give you some more details. MetalMuncher, glad I could help. 2 suggestions though, firstly you might want to raise your tempering temp up a minimum of 6 C (that would be about 176 C, or 350 F) but I would recomend a higher temp of 375F - 400 F (190 C ~ 205 C). You can probabaly get by with the lower tempering temp on shorter blades that wont see some of the stresses of larger knives, but on a bigger knife that you chop with and really put through some punishment, they might be slightly too hard and brittle at the lower temp (unless you run a differential HT or differential temper). Also, depending on the type of oil you are quenching in, you might want to preheat it a little hotter (130 F -160 F, lower for a thinner oil, hotter for a more viscosious) And a note on edge quenching, while edge quenching works well for many blades, it cant be done very well on all blades, due to shape differences. Oil and water surfaces sit level, if you have a blade with large projections, dips, or negative curvatures, you will not be able to harden portions of the blade with the standard edge quench method. This kukri style is one example where edge quenching won't work that well. You could harden the belly just fine, but to get that back portion of the edge you'd practically have to harden the majority of the blade anyway (well this one is not quite as bad as a standard kukri, so you might be able to, you'd just have to look and see where the oil level would have to sit in order to successfully harden everything). If you wanted a differential hardening for something like a traditional kukri, your best bet would be to clay the spine. Again, if you need any more details, don' hesistate Graham

It looks like what happend was you firstly quenched way too hot, resulting in a very corse grain structure within the blade and excessive stress build up, which is just asking for a fracture. Second mistake was skipping tempering all together (I assume you didn't temper since you did not mention it) and went straight into trying to aneal the spine blade. This left all the built up stress from the quench still in the blade. You can't really aneal the spine of a blade after quenching, if you heat the spine red hot you are bringing the spine up to critical temp, where this red hot spine meets the surface of the water, the water will try to rapidly cool this section of the blade, and water is much too agressive to quench 5160 in without fractures. As a result you will be hardening this area of the blade. You can draw a heavy temper on the spine using your method, but you only heat to around 600 F max (the deep blue color) not red hot. Since you heated the spine red hot it probably reached critical temp and you had the blade in the water which was attempting to act as a quenchant, you lowered the blade into the water slightly which quenched an area of the blade that you had heated, and the resulting stress caused the center of the blade at water level to expand which stressed the edge even more, it found a stress point in a gouge along the bevel from grinding at corse grit and pulled the bevel apart and split the blade at the water level. I do not think this happend from an existing fracture from the initial hardening. So basically you had everything working against you, huge grain and additional stress build up from quenching too hot, lack of tempering along the edge to reduce stress from quenching, heating the spine to critical and having it in water (the act the pushed the blade too far), and leaving course gouges from grinding to act as stress risers. For succesful HT temperatures are key. As mentioned, get a magnet to check the blade temperature for quenching. Unless you have consistant lighting conditions all the time you will not be able to judge temperature based solely off color. You don't want to overheat the blade before the quench because once you exceed critical temp, grain growth begins, the hotter you get the larger the grain. Forging the blade will result in large grain structure, as a result, this grain must be refined before hardening. To do this you must normalize the blade. To normalize the blade, heat the blade to critical temp, make sure the blade is evenly heated, and allow it to air cool. Do this a few times (I usually do 3 normailization cycles, reducing the temp gradually each cycle). Once the blade is normailzed it will have a good refined grain structure that is uniform throughout the entire blade. After normailzation you can go for the hardening quench, just make sure not to overheat the blade and to quench from critical not drastically above. Following the quench there is a huge amount of stress built up in the blade from the expansion caused from the formation of martensite, this stress must be relieved to make the blade usable without cracking (in some cases with some steels if you let a blade sit for a couple hours after quenching without tempering the resulting stress can crack the blade). To temper throw the blade in the oven for a few hours at around 375 - 400F (for a through hardened piece of 5160). This tempering will relieve stress built up in the steel from the quench and slightly reduce hardness to create a tough blade. Then, after tempering the entire blade at this lower temperature, if you want to further soften the spine you can submerge the edge in water and heat the spine to roughly a blue color (you will have to sand off the oxidization from the quench to see the temper colors run). If you want to differentially harden the blade (as in not hardening the spine at all) you have 2 options, edge quench or clay the spine. All the normalization and tempering still applies.

It depends on your plans for the blade/billet. You could use mild in the mix if you were doing a multi bar billet with high carbon billet edge wrap (like the old viking style pattern welding), or if you did san mai (taking a piece of high carbon and forge welding your damascus billets around the outside, thus when you grind, the high carbon is exposed at the edge). But if you don't plan on doing one of these methods, the blade you get will not be able to be used. As Woody said, the mild wont harden so you will have soft layers exposed at the edge of your blade. Better to choose steels that will harden sufficiently for the blade. The 1095 and 15N20/L6 mix Woody recomended is very nice (1095 will etch black, and the nickel in the 15N20 will leave it silver giving huge contrast) and something I use alot in my damascus. Also, 5160 (spring steel) can be a bit more challenging to forge weld if you arent good at forge welding yet, so might want to get some practice and get comfortable with forge welding before trying to mess with too much of that. Forgot to mention, its also important to choose steels that are somewhat simiar/compatable with each other. You want to find steels that have similar critical temps, similar quenching procedures, similar hardening characteristics, etc. Otherwise you can have billets pull apart in HT since certain steels expand at different rates.

With normalization I run 3 step down cycles, stepping down the temp gradually with each cycle (First at (maybe a hair above)cirtical, second at critical, third slightly below). After I pull the blade from the forge I pretty much let it cool down all the way to room temp (at least to the point where I can grab it barehanded) before going back into the forge for the next cycle. I also straighten the blade out in between these steps if it needs it. I don't want to set a hot blade on the anvil or in the vice because it will cause uneven rates of cooling, which is something you try to avoid with normalization. I usually HT multiple blades at a time, so while one or two are out cooling, the next is being heated so I don't waste excess fuel. A magnet is not "necessary" to judge temps if you are comfortable enough judging by eye. The only problem is that you have to have consistancy in your lighting in order to do this. If you HT in pure sunlight, indirect sunlight, shade, dim shop light, moonlight, or pure darkness the color of the steel will appear drastically different at the same temp in these different conditions. This is why a magnet is a good idea. Even if you are great at judging temps by eye, it doesnt hurt to double check with a magnet instead of risking a perfectly good blade. The magnet will also help you to get a feel for what critical temp looks like in different lighting conditions. Idealy a thermocouple or pyrometer is the best method to know the exact temp of your blade, but if thats not in your budget a magnet is the next best thing. The tempering temps depend heavily on what type of blade you have made and what type of uses it will see. A short blade for cutting that wont see as much stress as a big blade will be tempered lower (350F) a larger knife that might be used for chopping and will see more stress should be tempered at higher temps (400 F). A sword, depending on length, will required even higher temps (450-500 F). A good test to see if your temper is right is after tempering, sharpen the blade, then clamp a brass rod in a vice and lay the edge on it and apply pressure on the edge to flex it. If the edge chips out you know you need to temper a little more. Increase the temp run another cycle and test again. If the edge folds or rolls over on itself you know you have tempered too hot. Unfortunately if you do that the only solution is to re-normalize, re-harden, and re-temper. You will know a good edge as it should flex on the brass rod and return back to its shape without chipping or folding. Tempering times are highly debatable. Some argue only an hour, some two, some a lot longer. Tempering longer will not hurt the blade at all (only going too hot in the temper will cut blade performance). I would say an hour is the minimum time you would want to go, but longer is definately better. I usually run a minimum of 2 cycles at an hour a piece, and straighten any warps or bends in between. But more often that not I will run a couple more just for good measure. Some steels will want more time than others and the method suggested by viking-sword will ensure no problems. Another thing I would recomend when you are trying to perfect heat treating is to make a few blades just for destruction. I know it seems like a waste to destroy hard work, but in the long run its worth it to really see what is working and where you might be going wrong. Make a knife blade, HT it, test different tempering temps, then take the blade to destruction. Chop up some lumber, cut some rope, etc and see what the edge has done (chipped, rolled, still sharp etc) Then do blade flex tests to see how far you can flex the blade before fracture (be careful doing this. Use full face shield, heavy leather apron, gloves, etc. Dont want fragments of blade to get you). Once the blade breaks inspect the grain of the steel. See what the problems you ran into were (large grain, little flex, soft edge, or whatever it might be) adjust your HT methods and test another. Do it until you get it right. This will tell you huge amounts about the quality of your HT and will help you to perfect it for a particular steel. Additionally you will know if future blades HT with the same method will perform to your standards. Once you have the HT down you can really start to work on the other aspects of knife and blade making. Its pointless to make a nice looking knife if it will not perform sufficiently. My belief is function first then astetics. Its also good to do a destruction test on a blade every now and then anyways to ensure that you are keeping your quality up, and if you start messing around with new steels and need to work out bugs in HT, destruction testing is a good idea too.

Some of the HT depends on what you are making (the temper cycle to be specific). Your steps leading up through the hardening are fine (but with normalization I let it air cool quite a bit past just loosing its color). The only thing I can see is your tempering might be off (again depends on what you are HTing). If you are doing a knife, 230 C is a bit too high. For knives you want to be somewhere in the 350-400 F (175-200 C) range. A sword will be higher (about where you mentioned). And these temp ranges won't be the same for other things you might be making (chisels, springs, etc). Be sure to research what tempering temps are necessary for your particular item. And I would recomend tempering for quite a bit longer than 20min. I usually do 2 temper cycles at about an hour a piece. 2 hours tempering might not be completly necessary, but I wouldn't go much below 1 hour.

It does look like your grain structure was quite large. Grain growth occurs some durring the forging process where you are continually heating the blade and working it at those temperatures for extended periods of time (reheating over and over, etc). This gives the grain an opportunity to grow. I have also found that quenching too hot can cause larger than desired grain. Heating the steel hotter than necessary for the quench will give unnecessary grain growth. This is probably your main cause if you think you went too hot (and would explain why the grain at the tang is more refined since it was quenched at a slightly cooler temp). Best thing to help prevent this is to be really careful with your quenching temperatures. 1500 deg F (approx critical temp range for most steels) is only about a cherry red. In sunlight you wont be able to see this too well. Keep a magnet handy and periodically check for non-magnetic temp until you can figure out what the color of the steel at that temp looks like in your particular shop lighting. Also, be sure to normalize the blade before you do your hardening quench. Normalization is a crucial part of the HT process that is often overlooked at first. To normailize heat the blade up to critical temp (dont go too far above it), make sure the blade is heated evenly over its entire length. You can burry a pipe in your coal/in your gasser and let the pipe heat up, then stick the blade into the pipe, the non direct heat from the pipe will help heat the blade at one consistant temp and will prevent hot and cold spots. Then once the blade is up to temp, remove it, hang it from the tang and let air cool. I usually do a step down normailization in 3 normalization cycles, each one a progressivly lower heat. These normalizations will give you consistant grain structure through out the steel (helping to prevent hard and soft spots) and will help to refine your grain structure.

Hey Geoff, How have things been lately? Here's some of the basics for you: "Pearlite" is the softened structure of steel that you attain through annealing steel. It is composed alternating bands of ferrite (iron) and cementite (iron carbide). When you heat steel above its critical temperature, austenite forms (simply put, the crystaline structure of the ferrite expands, allowing the iron and carbon go into solution, forming a FCC crystaline structure, a cubic crystal with the iron on the corners and the carbon centered on the face). If you cool the steel slowly the carbon will diffuse and will form pearlite again. The slower you cool, the greater amounts of carbon will be able to diffuse, the more pearlite will form and the softer the steel will become. If you cool austenite very quickly (through quenching), the carbon will not diffuse sufficiently enough to form pearlite structure and the result will be martensite (or bainite, depending on the cooling rate, but martensite is the most "common" structure refered to). Martensite being the hardened structure of steel, formed when the carbon is "trapped" within the FCC strucure of austenite when it suddenly contracts from the rapid cooling, and in its contraction distorts and forms a body centered tetragonal structure. This is a much more ridigid structure, therefore it allows for much less deformation, which is "hardness". The quicker you cool steel the less carbon will diffuse out of solution, the more martensite will form and the harder it will become. However, with higher carbon steels, you can cool them too quickly, forming too much martensite. The crystaline structure of martensite actually takes up more room than that of pearlite, resulting in expansion, (thats why differentially hardening a katana causes it to curve, since the edge is being hardened (forming martensite resulting in expansion) and the spine is not being hardened (pearlitic strucure)). This expansion of the martensite structure, paired with the rigidity of the structure will not always allow for the deformation and stress caused through this expansion, and the structure fractures (this is why quenching oil-hardening steels in water causes them to crack). In cases where there is more carbon present, more carbon will go into solution, meaning that it will take slower rates of cooling to diffuse this additional carbon. This extra time required for diffusion is why higher carbon steels will become "harder" (since within the time it takes to cool, more carbon remains in solution, so more martensite will form) than those with less carbon, but it is also why they must be cooled slightly slower durring hardening (oil and air quenching, instead of water or brine, depending on the steel). There are also alloying elements added to some steels to effect the rate of diffusion and other characteristics. I actually came down to the shop this weekend, going to pick up a 100 lb propane tank, so if you are not busy with anything else and need to know more, you are welcome to come down.

Just a couple of thoughts, Firstly, I am in agreement that there should be some sort of structure present for the knife chats, making topics important. Why not impliment a thread where people who planned to be in attendance for the following weeks up comming chat could post suggested/requested topics to discuss and a few of the most popular could be selected (depending on how much time the depth/complexity of the specific topics allow for), sort of like Mitch's calendar suggestion. This would allow for whoever presents to have a clear topic set and give them a little time to prepare. This could be used to determine chat topics multiple weeks in advance if needed and make things go a bit smoother, and could even allow for BP type presentations to be developed for certain topics. Secondly, others have expressed concern regarding the differential in skill levels present durring chat. If topics are too advanced, beginners are overwhelemed, if topics are too basic, those more advanced get bored. What about dividing the chat evening into two segments, one more geared for beginners and the other towards more advanced topics? My thoughts are both groups would benefit in this manner, and it might help keep things more organized. The beginners could show up first for their's then could either stick around for the more advanced discussion or head off, and then the advanced discussion could begin. It would also cut down on the crowd a bit which I think could help with the side chatter and distraction. And finally to address the issue of excess, non-related chatter, maybe there should be a list of knife chat rules developed and posted somewhere, with things along the lines of: hold questions until the end of the presentation, if the presentation has already began, please enter quietly, keep side discussion to a minimum/no talking durring presentation, or somethings along those lines. Anyone who refuses to stick to the rules could then be asked to leave or booted (if you have been granted the high and mighty power to do so Steve ). Just a few of my thoughts. Don't have to pay attention to em if you don't want to, since its rare I get the time in the evening to attend anyway ;)

Just a little FYI, "pearlite" (I know that was probably a typo, and you meant perlite, but I thought I would throw out some metallurgy ) is actually the softened structure of steel that you are trying to attain through annealing. It is composed alternating bands of ferrite and cementite (iron carbide). When you heat steel above its critical temperature, austenite forms (simply put, the iron and carbon go into solution, forming a FCC crystaline structure). If you cool the steel slowly the carbon will diffuse and will form pearlite again. The slower you cool, the greater amounts of carbon will be able to diffuse, the more pearlite will form and the softer the steel will become. If you cool austenite very quickly (through quenching), the carbon will not diffuse sufficiently enough to form pearlite structure and the result will be martensite (or bainite, depending on the cooling rate). Martensite being the hardened structure of steel, formed when the carbon is "trapped" within the FCC strucure of austenite which essentially contracts, and in its contraction distorts and forms a body centered tetragonal structure, which is a much more ridigid structure, therefore allowing for less deformation, which is "hardness". The quicker you cool steel the less carbon will diffuse out of solution, the more martensite will form and the harder it will become. However, with higher carbon steels, you can cool them too quickly, forming too much martensite. The crystaline structure of martensite actually takes up more room than that of pearlite, resulting in expansion, (thats why differentially hardening a katana causes it to curve, since the edge is being hardened (forming martensite resulting in expansion) and the spine is not being hardened (pearlitic strucure)). This expansion of the martensite structure, paired with the rigidity of the structure will not always allow for the deformation and stress caused through this expansion, and the structure fractures (this is why quenching oil-hardening steels in water causes them to crack). In cases where there is more carbon present, more carbon will go into solution, meaning that it will take slower rates of cooling to diffuse this additional carbon. This is why higher carbon steels will become "harder" than those with less carbon, but it is also why they must be cooled slightly slower durring hardening (oil and air quenching, instead of water or brine). There are also alloying elements added to some steels to effect the rate of diffusion and other characteristics, but that is a whole other topic. Anyway, hope I didn't get too carried away ;)

Hopefully without eating up more of a post than is necessary, I will respond to a couple of your points and call this all good. Firstly, let me state that I do not "assume" a more acute edge angle will produce a sharper edge, it will. And this is true in practice and theory, HOWEVER, only to the point, if I may quote what I mentioned in my previous post, "within the physical limitations of the steel microstructure" (which was meant to directly address the issue you just brought up). If you could somehow achieve a physical structure that would support edge angles of small fractions of a degree you would have an edge amazingly sharper than one of 10,15, or 20 degrees. It is not practical to put in practice due to material limitations, but true none the less. Perhaps I did not place enough emphasis on material limitations originally, which is partly my fault, and partly due to the nature of the complexity of the topic itself, which will not allow certain issues to be mentioned without addressing each and every aspect of all things relating to it, in great detail. This tends to prevent condensing ideas, which is what I try to do to keep things short and simple. As a down side, some of these things usually end up getting passed over as being implied or as "common knowledge". I disagree with the way this is stated, but mostly agree with what you are trying to say. The angle/geometry of the edge IS the principle reason behind why the knife is sharp and can shave very well. Edge geometry is the "principle" behind why anything is sharp, its what makes an edge an edge, its what makes an edge "sharp," and its why some edges cut well and others don't. BUT, and I say again, but, proper edge geometry i.e. the acuity of an angle, can only be achieved as a result of having firstly and most importantly, proper micro structure, and secondly, proper sharpening technique. A better micro structure present within an edge will allow for greater acuity to be achieved within the edge, and therefore facilitates sharpness, making it physically possible, but it is not the "reason" behind it, the geometry is. Both are dependent upon the other to achieve sharpness, and BOTH are equally important in achieving sharpness. Afterwards comes sharpening skill to get them there. And as a result of everything stated above, I must disagree with your statement: I believe they have extensive application in knife/blade making (granted not the actual drawings and proportions themselves, but rather the principles that they illustrate). The reason being that one big crucial thing is being overlooked (or at least hasn't been fully addressed yet): the structure of the material that is supporting the edge itself (not the micro and grain structures, but rather the physical mechanics of the "foundational" structure that the edge/edge bevels rest upon, or in simpler terms, how the shape and thickness of the material present both at the beginning of the edge bevels, within them, and throughout the rest of the blade effect the edge performance). Meaning, (in a simply put example) dimensionally, convex ground blades must be made "thinner" to facilitate the same edge angle as one present on a flat or hollow ground blade, which will effect not only the strength of the blade, but of the edge itself. So again back to the point made with the illustrations. Considering blades of equal proportions, and assuming the physical limitations of micro structure are not exceeded, proper sharpening technique is used, etc., flat and hollow ground blades can achieve more acute edge angles, and therefore "higher levels" of sharpness (again, do not overlook that I said blades of equal proportions). That may or may not be "important" depending on what exactly the blade is intended to do, and if its dimensions are relevant to the overall intended use and function (but in most cases they most certainly are). So I still maintain that my original statement regarding blade geometries and sharpness is correct, but perhaps not viewed correctly or understood without clarification, which is my fault. That is due to how I view blade design itself. I suppose my thought process would be more along the lines of "blade engineering" as I approach a blade like an engineering problem. Firstly analyze what the "problem" you are trying to solve is i.e. what function/need are you trying to make a knife to fulfill? This gives you the performance criteria that the blade must achieve. This usually immediately begins to dictate size, shape and rough dimensions, not to mention cutting edge type/needs, required for the general types of stress and cutting operations the blade will be used in. Next I look at the materials required to perform under these conditions, with the main focus being blade steel choice and how to execute the HT to achieve the correct microstructures for both the edge and the rest of the overall blade. Then once I have this overall "blade" fit together, I look at what exact edge geometry is needed and how it is to be integrated, and tweak any blade geometry or dimensions as necessary. Starting with the edge geometry and theoretically constructing the rest of the blade around it seems very backwards to me, but to each his own. That being for formal blade design. But sometimes when beginning to forge a new blade, I go into it without any previous considerations besides the steel, and let the steel dictate what it "wants" to be, and I worry about the other details as I go. And finally (about time eh?) I did not think this thread was created/intended for beginners, but rather was more about the general principles behind sharpening, and sharpness, and the whole underlying reasons. Someone mentioned blade geometry, which lead to my discussion on edge geometry/blade geometry relationships. Therefore, since I viewed this as a thread more for discussion rather than information for beginners, I didn't go into as much detail as I should have, and neglected to clearly state some things. I am glad you brought this to attention, as I said before, I do not want to be responsible for spreading misconception if possible. Hope the rest of your journeymanship goes well and that you are successful in your endeavors.

It seems like you are just focusing on only the edge of a knife, and overlooking the rest of the structure of the blade that it took to get to that edge. How can you achieve a fine edge without taking the rest of the geometry of the blade into consideration as well? The geometry above the edge will ultimately help to dictate the edge geometry itself. I don't know how edge geometry is a "wealthy" way to describe things. That is the terminology I am accustomed to and is widely used; you might be used to different due to your different background. While it is true that most edges are just angles, there are also convex edges which are actually composed of arcing surfaces coming to a single point, may seem like a technicality, but that falls under the realm of edge geometry as well, and convex edges perform differently than an edge ground with flat geometry and cant be overlooked either. Convex edges are achieved through use of slack belt grinding when applying the edge, and to a degree (though not purposefully as in the previous case) through stropping practices, and other inconsistencies in human grinding movements. Convex edges will cut, and will cut very effectively, can shave, etc if done correctly. Pay attention to my wording here, note I said they have the "ability" to be sharper, not that they will be. More along the lines that implementation of such blade geometry CAN be used to achieve a more acute and therefore sharper edge than a convex grind, and we are not talking about implementing secondary edge bevels here, that is something I should have clarified, my apologies. I think maybe some illustrations are in order to help you to understand what I am trying to say. Back to what I originally said, If you look at the illustrations bellow, they show what I am trying to say. I apologize for the poor quality of the pictures, but they should give the idea. Note, I drew these on AutoCAD and used the same blade thickness and blade width for each sample crossection, therefore each crossection has the same dimensions/proportions, as stated above. They are a bit exaggerated(I think the blade is 1/2" thick x 1.5" wide (edge to spine)), so ignore the impracticality of some of the illustrations, but that was necessary to allow for enough visual distinction, and it doesn

How can you say that blade geometry has little to do with the sharpness of a knife? Blade geometry is all about how a knife cuts, both how it moves through a medium as well as the sharpness of the edge. Blade geometry effects the thickness of material at an edge and dictates the angle that the edge is set at, as well as the structure present at the edge. A more acute angle for the edge means a sharper edge. This is edge geometry. Edge geometry is a part of the overall blade geometry and both are dependent on each other. Flat, hollow, and convex grinds all effect material thickness and angles both at the edge and over the entire blade. Flat and hollow grinds if applied to the same blade/same dimensions/proportions will result in a more acute edge than a convex grind based solely on their geometry, you can not argue against that, and that was my point above. The geometry of a blade with a flat or hollow grind allows for a more acute edge and therefore can attain a higher level of sharpness. Proper heat treatment is a requirement for attaining (and especially retaining) a very fine edge, however the actual sharpness of the edge is all dependent on the geometry of the edge itself which is also dictated by the overall blade geometry (which includes dimensions/proportions). A good HT on a blade and improper blade and edge geometry will not result in a super fine, razor edge, that is not outside of reason, that is common sense. Likewise I do not argue that only edge geometry matters. Correct edge geometry on improperly heat treated steel may allow for a very sharp edge initially but it will not last very long, and physically you will not be able to bring the edge down nearly as fine due to lack of rigidity within grain structure. This I agree with completly. But the actual edge sharpness is still dependent on its geometry and how that realates to the rest of the blade. Thats pretty much what sharpening is all about, adjusting the geometry of the edge and how it relates to the geoemtry of the rest of the blade. Edit: I went and watched his other sharpening video on youtube, and the neck knife he uses is a "flat" ground blade, you can tell its flat by looking. He might not have "ground" it with a grinder, but its beveling is flat and fits the defination, and as he sharpens he lays the entire primary bevel on the stone and brings it down to an edge (no secondary edge bevel), then lifts the angle slightly for stroping purposes. This allows for the super acute edge he attained, as well as the overall thin crossectional area of the blade. His sharpening techniques and blade type all rely on blade geometry for their sharpness (not excluding good steel & HT), which only helps to illustrate my point.

Actually, flat ground and hollow ground blades have the ability to be sharper than a convex ground blade. With a flat ground blade you have the ability to pull the primary bevel all the way down to the edge and foregoe a secondary edge bevel, creating a super thin, super sharp edge, and even more so with a hollow ground blade. Perhaps it takes more patience and skill to work with flat ground and hollow ground blades so a convex grind might be "easier" to get sharp. And perhaps it is a bit easier to pull the convex bevel down to an edge without a secondary edge bevel. However due to the extra material and thickness present at the edge, a convex ground blade will not be able to attain the sharpness of a completly flat or hollow ground blade (but not to say that you can't get it shaving sharp and then some ) You are correct with your observation that convex edges do hold up a bit longer under use than flat edge bevels. This is because there is extra material present at the edge to help support it, and the overall shape of the edge and added thickness helps reduce stress risers and makes the edge less prone to rolling, folding , and chipping. On most working knives I usually do a convex edge grind as a secondary bevel. I usually pull the edge down pretty thin or almost sharp before going into the secondary edge bevel to help make the blade sharper. For more speciality blades that require finer edges I might foregoe the secondary edge bevel and pull the primary bevels down to the edge.

Thats a hugely open ended question. Thats like asking what is the best car to drive, whats the best type of knife there is, etc. And the answer is it really all depends. Depends on the knife size, shape, style, intended use, if your doing monosteel blades, pattern welded blades, full hardening, differential hardening, what kind of heat treat setup you run, your individual skill, and personal perefrence. There are many good steel grades and alloys for knife making and each have their own special characteristics and attributes. Some of the most common and widley used steels are 5160, the 10xx series (1050, 1060, 1075, 1084, etc, all the way up to 1095), O1, W1, W2, L6/15N20, and 52100. Each of these steels if heat treated properly will make a fine blade. However some are more suited for certan applications than others. For instance the higher carbon steels, like 1095, harden a bit more and are not quite as suitable for a blade that will be long and required to flex and absorb more stress. At the same time, the lower end of the high carbons are more shallow hardening, and will not reach the same hardness for use in a small blade that you want to hold a great edge. Additionally some of the steels are a bit more friendly to work with, 5160 is a pretty forgiving steel both under the hammer and durring HT, however 52100 is a bear to move under the hammer and is a bit more picky with its HT. There is also some cost differences in steels as well that one has to consider. As you can see there are a lot of variables and things to consider in choosing the right material for a blade. The best thing I can recomend is to get some of the different steels, research the steel, how to HT it etc, then play around with it until you get a feel for it and can achieve good performance in the HT. If you can find a steel that works well for you, then it is a good steel for a knife. There is no one best steel that performs well for every type of knife. The old files you are working with are probably either 1095 or W1 and make very good knives. Additionally I would say that for a good tough knife, you cant go wrong with 5160. 5160 is pretty forgiving durring forging, it HT's well, and if your starting out is a pretty good steel to learn with. The 10xx series high carbons are also good for starting out. W1 and O1 make super knives as well. Like I said, they all make good knives if you know how to work with and HT them. Research and experiment. Graham

Interesting you should bring this up as I just shaved last night with the new EDC I made for myself. The edge geometry on it is not as well suited for shaving since the bevel angles are not quite as acute as with some blades, but it still did a fairly decent job. Getting a knife to shaving sharp is not as tricky or challenging as you might think. The main things that have to be taken into consideration are edge geometry, blade material and HT, then sharpening technique. The biggest of these is edge geometry. Most working knives, and most factory produced blades do not have edge geometry suited for shaving. They have less acute angles to create an edge with more meat to it to survive abuse. A thin edge more suited for shaving would be too fragile to withstand the abuses of a working knife. Like Rich mentioned, a blade should be sharpened for its intended usage. If you're in the jungle clearing paths you arent going to use a straight bladed razor, and if you are going to shave, your machette is probably not the ideal thing to use. Right tool for the right job. If you have a knife with correct blade geometry and is suited for uses where a very sharp edge is required and its made from decent material with a good HT, then like I said its not horribly difficult to bring it to shaving sharpness. Its usually as simple as grinding the edge with a fine grit belt (I usually use a 600) until a wire edge forms. The wire edge indicates you have brought the steel down to as thin as it can maintain itself. Next you have to remove the wire edge/burr. I have a 2"x72" leather belt strop that goes on my grinder that pulls the wire edge right off and stropes to shaving sharp quite quickly. You can also use a buffing wheel with buffing compound to pull the wire edge off and polish the edge. Thats usually all it takes to get a shaving edge, maybe a very light touch up on a super fine stone, or even a butchers steel just to return some of the "roughness" to the edge. Thats the way I usually put the inital edge on my blades. It makes for a pretty sharp edge that holds up quite well, and is fairly easy to maintain/sharpen.

There is also paper micarta that is factory produced, don't forget about that. Theoretically you could imbed a good number of things in resin and come up with all manner of things, but thats probably easier said than done. If you are wanting to use organic materials like you mentioned, you would firstly have to ensure that they are completly dry, but in that case, things like dry leaves and such become fairly brittle and as soon as you start trying to layer resin with them, will most likley fall apart, so I am not sure how exactly that would turn out. Cloth works well because it is easily layered, and will stretch/conform to things decently. The reasoning behind micarta was the need for a strong synthetic material, resin by itself is fairly brittle, but with the cloth layers to add a bit of flexibility and something to hold the resin together, it creates a very strong material, kind of like adding rebar to concrete. I wouldnt think leaves or the like would hold up that well. Thats my thought anyway. Maybe something like reeds, or birtch bark would work though. I have heard of guys taking things like synthetic sponges and impregnating them with resin and squishing them in a press to give some interesting results. You can always give it a try though , you never know what you might come up with.

Thanks everyone. Glad you all like it. Going to try to finish the sheath for it by tommorow and will post a couple pics of it when finished. If the weather decides to cooperate I plan to be out in the shop trying to turn out a few more.

Well folks, I finally decided to come back around here after some time away. Got back into the shop after a very long and even more unpleasent time span. I have never hated life more than when I am away from the shop, the withdrawl symptoms are horrible . I have had this one rough forged and partially ground since sometime in late summer and its been a super long time since I have done a full tang, so I thought it would be the first to jump on to get back into the feel of things. I really had to sweet talk my KMG and give it some proper love before it would forgive me from neglecting it for so long . After about a good 4 or 5 months without really grinding anything much it felt like I had to re-teach myself everything from the beginning . I am going to keep this one for myself, figured it was about time that I made myself a knife for EDC, and I figure it couldn't hurt advertising if I actually had a knife I made with me at all times for potential customers to see. This is the first knife I have made with a blade short enough to comply with general carry / concealed carry laws here, or I would have been packing my own work for some time. Anyway, here is the result, Forged 5160, edge-quenched, full tang Blade length: 3.5" OAL: 8.5" Black canvas micarta grip scales Mild steel bolster w/filework and mild steel pins Anyway, let me know what you all think, the good and/or the bad. Graham