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Tim Mitchell

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Tim Mitchell last won the day on May 5 2021

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About Tim Mitchell

  • Birthday 08/06/1975

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    New South Wales, Australia
  • Interests
    blacksmithing, knifemaking, wootz manufacture, carpentry, astronomy.

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  1. Sorry to hear you are under the weather mate. Hope you mend quickly and I look forward to seeing you there when you can.
  2. This is our promo video.. IWS Launch Promo Video
  3. Hey Everyone, I just want to make all those interested in Wootz Steel aware that we have now launched the International Wootz Society. It has been almost a year in planning and setting up, and we are now open and accepting members. The Society is for smiths, collectors, historians, researchers and anyone who is interested in the production, history or identification of historical crucible steels. We will be having testing of smiths and certification of standards of skill level for those who desire it. We also aim to educate the public with correct historical and technical information concerning Wootz Steel. The founders and board members are myself, Jin Singh from Wootz Militaria, Peter Burt of Peter Burt knives, Sebastian Szukalsky of ipostswords and Mert Tansu from Tansu Knives, Keith Fludder has also been helping out. The website is https://internationalwootzsociety.com/
  4. Thanks for the videos Jacob. There were all kinds of different quenches from ancient times and some of those only worked on specific ingot chemistries at the time. It was common though to not dunk the blade in like you did here, but to only put the edge in and rock it back and forward. They even did this with a heated light oil. One very important thing that I would underline if I could is that every new formulation is a NEW STEEL.. and so what has worked in the past or in historical recipes with one steel formulation won't work the same with the new one. Wootz is just like all other steel in that there are different formulations and the only thing that they all have in common is that they have a dendritic structure to begin with. That will make some of the ways we treat ingots similar but there are still many differences and so there will be failures and lots of learning until you find something that you know well and can get a really good quality product with. One other piece of advice I would give is that you do your heat treating in the dark or in very low light so you can get a better gauge of the temperature at different stages of your quench.
  5. No worries Jacob, I am glad that you have been getting some benefit from my wootz posts on here. I am really passionate about providing good information to make things easier for people like you, starting out in the craft. Having a little bit of Mn in there is good for hardenability of the blade especially if you have been making a super clean steel. The old blades used to have Phosphorus in them which aids in hardenability and under tempering can actually make the blade brittle. It wasn't a problem for them back then but with modern heat treat it can be an issue. The old blades also had copper which aids in hardenability as well as a little Mn which wasn't uncommon. So you have to have some elements in there which aid in getting the hardness in the blade on quenching, whether that is air quench, oil or very careful momentary water slicing quench. As far as hamon formation, you may likely get a hamon but the type of hamon is different due to the acid etching and heat treat of the blade being slightly different. Wootz normally speaking (with lower Mn) will have a thickness hardening nature. Over about 1/8" thickness it usually won't harden and on your blade that would mean a nice differential hardening line... However the Mn level in your blade aids in hardenability and so it will go beyond that thickness in hardening. You can counteract that by not doing a full plunge of the blade but by doing more of a edge in a long bath kind of quench, cutting edge first. Interrupting the quench. I often recommend that you don't use your final sword to do heat treat tests. Take a wedge of the same ingot which has been through the same processing as your blade and do a quench test to see if it gets the hardness you desire and if you get the differential hardness you are looking for. If the wedge test is a success you can have more confidence that your blade quench will go well. Essentially you are dealing with a unique and new steel each time you change your formulation of your ingots and that means that your processing changes and your optimal heat treat changes. So if you want the best result for your blade.... TEST A WEDGE... Now one other comment about your V levels. When you increase carbide former levels significantly you will have them resisting the conversion of the pattern in the ingot to laminar structure. So the higher the CFEs get the more dendritic the ingot will stay. This is the sort of effect you see in the higher carbon percent ingots. There are ways to get around this issue but it can be risky. Forging at 1100°C in the first stage should give you a nice laminar pattern, I look forward to seeing your results! Cheers, Tim.
  6. DO NOT WATER QUENCH!!! Wootz is not Japanese steel and you can only do a water quench if you use a slicing action in and out of the water. You have a significant level of Manganese in that steel (thanks for providing that, it makes giving advice easier) and so the steel will be very hardenable and could get too stressed from the water quench. Now you may wonder why I say not to water quench even if the steel has similar chemistry to other water quenching steels. The reason is that not only do you have a much higher carbon content than most water quenching steels, you also have a crystalline structure in the steel which creates possible crack locations. Japanese swords do not have this weakness. Most beginning wootz smiths and even many experienced smiths do not forge their ingots high enough to be able to get full conversion from a dendritic structure to a laminar structure. Hopefully you will have enough V in there to make the pattern visible enough. Manganese darkens the matrix in the background of the steel and chokes out the pattern from Carbide Forming Elements like Vanadium. As a result you have to increase the Vanadium level to counteract the Manganese content in the blade or you will get no real pattern. So back to how to quench... using a heated thin oil is best for hardness, however the old blades were often only partially edge quenched which left the main part of the blade Pearlite and the blade edge only quenched Martensite. No tempering was required as the heat from the unquenched spine would temper the blade edge. Other methods were used such as a warm air blast which makes a very fine Pearlite structure in the blade. But for your purposes you probably will want to do a full quench in light oil which has been well heated. Of course it goes without saying that you need to do several Normalization cycles on the blade before you do the hardening quench to relieve the stresses in the blade. Good Luck! I look forward to seeing the final pattern in your blade. Well done for having a crack at Wootz!
  7. Good job Jacob! It is encouraging when you finally get a successful blade. I am glad that you have found the material on this forum helpful. When I first started out there was very little material out there, but we now have so much more available to new smiths which can make their journey much simpler. We also know so much more now than even at the end of last century and more wootz smiths are sharing and collaborating now than ever before. It is an exciting time to be part of this community of artisans. All the best and I look forward to seeing your future blades!
  8. There is a very good reason that we suggest washing out and then filling the drum or gas bottle with water and letting it sit for some time before cutting the top off... You can never be too careful! What a needless tragedy!
  9. Good Job on your first attempt AJ. It was a good test for seeing if you can get hot enough. For now though I suggest you make a basic blown burner and make sure you put a lid on that crucible.. having an open crucible will add several extra failure points and that is something that you want to avoid. Just stick a section of brick on it to keep the atmosphere away so you don't get too much porosity in your ingot.. Second thing... only use known ingredients especially when starting out. Using ingredients with unknown elemental composition is inviting Murphy to the party.. the source of cast iron, grey cast iron brake rotors has between 2 and 4% Carbon and it is high in Silicone which makes graphite form in the ingot (the grey in grey cast iron). Also adding Aluminium to "kill" the ingot is something that unfortunately Al and John did in their paper but it is a bad idea also. You need to keep Aluminium far from your ingots, it will also aid in forcing carbon out as graphite in your ingot. Graphite is your enemy when forging ingots, it makes them brittle and they will crumble under the hammer. There are ways to avoid disaster when forging ingots which contain graphite forming ingredients but they are not something that a beginning smith would be able to do easily, it is like dancing on a knife edge....
  10. You can get pure vanadium crystals of metal from some sellers on Aliepress and you can get Ferro-vanadium from Alibaba. It comes in grades from about 20%V to 80%V. It is essential to find a supplier who provides a material which is lowest in Silicone. Ferro-V is usually high in Silicone and you want to avoid that. Getting the material which is 80% means that even 1.5%Si is not going to cause you much trouble in your melt... but 3%Si and 20%V would be a problem.
  11. Things which will cause graphite in ingots is, Aluminum, Silicon, Nickel, Phosphorus and Borax. Carbide Forming Elements will help to prevent graphite formation in the steel if they are there in high enough quantities. The old blades did have Nickel, Phosphorus and Silicon in different levels, but the presence of other elements tended to help retard graphite formation. Also they forged things in a way and heat treated the ingots in a way which minimised the formation of graphite in these ingots.
  12. Green glass won't give you enough Vanadium if you have any decent manganese in your ingot. With those levels of Mn from the 1084 you will need between 0.2 - 0.3%V or Nobium in order to get good banding. Manganese chokes out the brightness of the Vanadium as it has black carbides. Actually I have never seen any evidence of V or other CFEs getting into the melt from the slag... it could do that for sure but I doubt that it would in high enough levels to actaully make a decent difference... I may be wrong but I don't think so on this.
  13. Good job getting your feet wet Al. I hope it goes well with forging it out, but I do have some suggestions for you. The borax flux should never be used as it will promote graphite formation in your ingot. Due to the higher Phosphorus level in 1084 you can be susceptible to graphite formation in the ingot. Because of the manganese level in this ingot you will find that the pattern will be dark and any banding will be finer than what you would expect. Did you add any Vanadium to the ingot? Without significant addition of some carbide former you will not be able to get much of a pattern. Anyway I hope it turns out well for you and look forward to seeing how you go in the future. Cheers!
  14. Hey Al, welcome to the world of making crucible steel! It can be a bug with sharp teeth! As far as making a furnace, I have used ceramic wool by itself a few times but it doesn't last long especially if you don't coat it with some kind of furnace wash. But that is a recipe for lung cancer down the road at furnace temps, disintegrating ceramic wool will go into your lungs and cause big problems if you get too much. You really need to make a furnace with a cast refractory cement lining. I recommend using around 2 inches of cement backed with the ceramic wool. That way you can use 1250°C rated blanket and not have any problems.. it is only for keeping the heat away from the shell and increase efficiency. Don't make the furnace too large or it will not work properly. Keep about 2 inches between your crucible wall and the crucible itself. Make sure you have enough room to get tongs in there to lift the crucible out later on.. Also line it with a zircon refractory wash which will make the bore last longer and will reduce the heat reaching your wool.. You can use thicker cement in your wall (it should be 1700- 1800°C rated) if you want to but remember that it is all thermal mass to heat up and that will increase the burn time to reach temp, and reduce efficiency. Take care to not make your vent hole too small, this is very important if you are using a venturi burner. Too much back pressure will cause problems, it is better to make a 90mm opening and then choke it down a little with a brick if you need to increase efficiency. A venturi burner will get hot enough to do a melt, but I am not sure if the T-Rex 1 inch burner is large enough to do the job quickly enough. The few smiths I know who use a venturi burner on their furnace for melting wootz say that it takes significantly longer to get to temperature than with a blown burner. This suggests to me that either the size that they are using is just a bit too small, or perhaps that the extra furnace internal atmosphere pressure which you get from a blown burner helps with efficiency and speeds up the melting process. I know of no smiths who have ever used ribbon burners for melting wootz and although if you have enough burners you may be able to get it to melt, I would be surprised to see it work without several burners in one furnace. Using a blown burner, even a crude one is efficient and so long as you use a flare cast in the wall of the chamber to keep the flame anchored at the wall, you will have success after a bit of tweaking. Raise the crucible up using a plinth to avoid the blast of the burner, and get a type S thermocouple ... or two.. they are cheap from Aliexpress, to monitor your temperature with it just peaking out of the chamber wall not quite at the level of the top of the crucible. Also set it up so you can put the thermocouple directly up from the bottom under the crucible, it will help you to make sure you don't get your melt too hot, a very common fault. The burner must enter at a tangent and hit the wall not the crucible or plinth directly for the best result. The two things to avoid when tuning your furnace are poor mixture and poor temperature control. You want it to be roughly neutral but not too oxidizing or carburising. Too many melts are ruined from having a mixture which is too rich or two lean especially with an open top melt. (usually a 3 to 4 inch flame visible above the vent is sufficient for a good mixture). Poor temperature control is a major issue, if you are guessing what your temp is, then you are much more likely to fail that is why I suggest using a thermocouple. One in the wall is very useful to help tune mixture if you know how, but it will show hotter than the crucible temp as you are measuring the air flow temp which is always hotter. When you work out how much hotter for the position then you are good to go. That is why one up the guts is a good idea at least for working out the difference and calibrating your furnace temp... there is no substitute for knowing your temp. The old smiths didn't have thermocouples, they had set bellows sizes and songs which kept the correct airflow rate, so their temperature control would have been very precise. There are other ways which require an open crucible but that has it's drawbacks too.. A thermocouple is easy, cheap and assures consistency from one melt to another, and they more than pay for themselves in the ruined materials they save you. Good luck on your journey, it has only begun....
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