Buzzkill

So, after looking up the specific video it appears that he used silicon carbide and fiber blanket to create the system and he did use it inside a microwave. However, he did mention that it was more suitable to fuse glass and that it's not the best way to melt metal.

IIRC these types of machines use the transformers from microwaves. They rewire the transformers with some very heavy gauge wire and only a few coils and then use electric arc for *melting* not smelting. I've seen a few videos over the years that are similar, but not sure if any were the specific one referenced. I've never tried to replicate any of the items myself.

Thanks for the suggestions. I won't use cloud based software on principle. I prefer to work offline as much as possible. However, since I have no experience with CAD programs I will look for something different than Blender. Thanks. I'll check it out.

If any of you guys have .stl or .obj files for these vortex burners that you'd be willing to share I'd surely appreciate it. I received a 3d printer for Christmas, but I've never used a CAD program before. I hate to reinvent the wheel anyway, but eventually I will teach myself to use CAD (Blender is the one I'm starting with) and I should be able to recreate what I've seen on here. However, if someone wants to help me out with a shortcut to the process I'm happy to take advantage of the opportunity. I understand if you guys don't want to freely distribute the results of your hard work and experiments, but if you are willing to share I'd be happy to send some money your way. PM me if interested.

Satanite is basically clay. It's not water setting. It is cured by heat. In thick layers it will generally crack/curl, and it's not very insulating. It's intended use is for joining high temperature bricks. The manufacturer is pretty clear about that. From the manufacturer Data Sheet: "Uses: Can be used to lay dense 50%, 60%, and 70% alumina brick, as well as 2800°F (1538°C) and 3000°F (1650°C) rated insulating firebrick." That's all the manufacturer says about uses. It certainly doesn't indicate that it should be used as the main surface for direct flame contact. It appears a lot of people do use it to seal fiber blankets and it's also commonly used on knife blades to assist in creating hamons. If you use it as a flame face and have good results that's great, but there are better materials for forge chambers that are roughly the same cost. Why not use (or recommend) a product better suited to the application? The same manufacturer makes water setting insulating high alumina bubble castable refractory

It might be better to change the angle of the blade itself compared to the handle then. If the eye was centered on the blade so there were equal amounts of "beard" above and below the central point then it should be fairly easy to configure it so the full range of the blade could be used without sticking knuckles in hot toppings.

Unless you want to be able to hold it at a position between vertical and horizontal I'd suggest just making stops so that it rests/locks into either of those two positions. Unless you found the center of balance for the grinder and set up your pivot accordingly, it will probably be fairly heavy in one direction, which coupled with vibration may make it difficult to keep in a position without something locking it into place. It looks nice and sturdy though.

I don't think there's enough chromium in 52100 to have this effect. I believe it's around 1.5% chromium, which would pretty much all end up as carbides in the steel I think. I use 80CrV2 a bit. It's lower in chromium than 52100, but it takes a nice dark etch. 5160 is another alloy that includes chromium but etches darkly. The alloys that contain nickel tend to be the "bright" steel when etching pattern-welded steel. I think you'd have to be near the point where there was enough chromium content in the steel to approach stainless classification before you'd see etch resistance.

This may be true generally, but getting the elements of the alloy all dissolved and evenly distributed throughout the piece can certainly be affected by time. Some of the elements can affect grain size. Regardless, it's not a guessing game here. The manufacturers tell us how to properly heat treat their products. Professional knife makers tailor some of these processes to match the dimensions of blades rather than large parts, but in either case there are recipes that, if followed correctly, *will* yield consistently good results.

There are a few possibilities. If you overheated the steel to the point where it was nearly burning, you may not be able to reduce the grain size afterwards. When broken the gain somewhat resembles cottage cheese at that point. If you burn the steel it is no longer suitable to use for a blade. If you normalized too hot you may not have been able to reduce the grain size much. For 5160 you might start your first cycle in the forging range, but your last cycle should be just barely above critical temperature. The magnet is your friend here. You want it to be non-magnetic, but just barely, on the last one. It is not necessary to cool down to room temperature. You should be doing this in low light and you only need to wait until the blade has completely stopped glowing before starting another cycle. Beyond that, when you were heating for the quench if you got the steel too hot that would again promote large grains in the structure. We have to get above critical temperature to get the transformation, but going hotter than needed weakens the steel. Those are the things I can think of that may have contributed to the excessive grain size you observed.

First priority - safety gear. If you don't already have them, then that includes eye and ear protection, respirator (even the disposable paper ones help when grinding), and non-synthetic pants and shirts. I recommend a leather apron and leather footwear with lace protectors as well. If starting with a $5K budget I also would make the next priority a 2x72" variable speed belt grinder with a minimum of 1.5 hp. A flat platen and at least one large contact wheel (8" - 14" diameter) would be included in that purchase. Whether you do strictly stock removal or forged blades you will spend a fair amount of time at the grinder. A healthy selection of belts should also be purchased. I recommend a few in the 24 - 36 grit range for hogging off significant metal when needed. I personally use 60/80 grit ceramic belts a lot, followed by 120 grit. I have some higher grit belts but I tend to do mostly hand sanding above 220 grit. I do like the Scotch-Brite surface conditioning belts for blades that will see a lot of use. No point in putting a mirror finish on a blade whose use will destroy it in short order. I use my horizontal/vertical bandsaw quite a bit as well. When doing strictly stock removal it is much faster and more accurate to get the profile on a vertical bandsaw than an angle grinder, imo. Hand held hacksaws come in quite a distance behind those options. Good drill bits (cobalt) and a medium size drill press can increase your precision and decrease your frustration quite a bit. If you plan to forge blades you're obviously going to need a forge, anvil, and hammer. If you have little to no experience forging I recommend purchasing or building a decent propane forge. That reduces the number of things you are trying to learn simultaneously. If you use coal or charcoal you have to learn fire management and keep an eye on the steel so you don't burn it in addition to all the other things you are trying to learn. For smithing small to medium size blades you can easily get by with an anvil or solid chunk of steel around 100 lbs., give or take a little. Don't worry about presses or power hammers until you have a fairly good understanding about how hot steel moves under the hammer. In the long run if you plan to make pattern welded blades you will want one or both of them though. You can definitely do PW blades by hand, but it is a lot of work. You should start with mono-steels anyway. Spend a little time/money on a good quench tank with a lid. Some people like the "tank inside a larger can" approach so that if flaming oil is dripping down the sides of your quench tank it is contained inside the larger can and you can put the lid over the whole thing to snuff the fire without much risk of setting your shop on fire. A few gallons of good quench oil is also recommended. If you have Parks AAA and Parks 50 (or the equivalent of both) that should cover the majority of steels you will use for blades. A tempering oven with good temperature control is also valuable. You can't really trust most toaster ovens, so if you use one you'll want to get your own oven thermometer to place inside and you'll want a tray of sand or something else that can act as a heat stabilizer to minimize the effects of the temperature fluctuations that are common with toaster ovens. If you want to get very precise with your quenching temperatures and tempering temperatures then you'll want to look at the electric ovens made for those purposes. Of course you'll need adhesives, handle material, pins, guard material, etc. as well.

We have a commercial boiler at work for in-floor heat. It will run on everything between kerosene and 90 weight oil. We do run the used oil through a filter before it goes into the supply tank. So far (several years) we have never had any trouble with fouling/clogging of the fuel system. We have the system serviced once a year to remove the ash buildup in the combustion chamber and to make sure it is functioning correctly. Those systems burn hot, so a lot of the byproducts people worry about are destroyed at the higher temperatures. Still, the exhaust stack is 10 feet higher than the roof of the building that houses it. If you filter the waste oil to remove particulates, and use a separator to get rid of the water if that's a concern, I don't think you'll have much of a problem with the burner clogging frequently - if it was designed to burn lightweight oils up to gear oils. If it was designed strictly to run on heating oil it might be a different story.

The short answer is unequal forces. There are a number of things that can cause this. The spine is usually thicker than the cutting edge, so those will expand and contract at different rates when heated or cooled. Especially on a long blade that can cause a "saber" effect when quenched. A blade that is ground slightly more on one side than the other compared to the center line will often warp. If a blade is a little hotter on one side than the other, that can do it. Moving the blade in a way that puts pressure on of of the sides more than the other while quenching can cause warping. Laying a freshly quenched blade on a cold anvil will create unequal forces. The bottom line is there are lots of scenarios that can cause warping, but if you started with a straight flat blade then something created unequal forces which became evident when the blade was quenched.

If the housing is aluminum then obviously it would have to be insulated from the forge chamber quite well to avoid becoming liquid. Can the fiber mesh be reasonably removed from the housing without damaging it?

Hmm. That looks a lot like the inner workings of the Richmond tankless water heater I installed last year. Mine runs on LPG, so if it fails I'll definitely scavenge the burner assembly out of it. Like the others here, I do have concerns/doubts about it holding up in a forge environment. However, if it does hold up that gives us another potential source for burners without a lot of casting. Thanks for bringing this up.

I think it would be less effort and a better end product to use the guts out of a toaster oven and an inexpensive PID controller.

80CrV2 is notorious for having a thick decarb layer after quenching compared to many other simple steels. It has become one of my favorite blade steels, but you do need to compensate for the decarb layer. If you do pattern welding with it this becomes very important if you want to see the pattern clearly. I recommend a half a millimeter or so that you plan to take off in the final grind in order to make sure you remove it all. FWIW I had a similar experience when I began using it. Quench, file test, curse. Higher temp, quench, file test, more cursing. I finally gave up on one and was going to make it a display piece. However, after grinding a bit I got down to steel that skated a file nicely. If you have some quenched pieces that you don't think hardened, you may want to grind a bit off the surface and check them again. Oh, and if you want to see the effect visually you can etch the blade. The decarb layer shows up as kind of a dull gray color. Once you get through that you should get the dark/black etch that you are used to seeing for hardened steels.

A few years ago I did something similar, but with aluminum. I had a hidden tang and cast the entire handle in place on the knife. Although it was a general success I've never done it again since that time, and I'm not even sure I can recommend it. I used the lost foam technique in a bucket of sand. Lost wax would probably produce a better handle. I had cut a slit in the bottom of the bucket for the blade to pass through and set the bucket on a container of water so that the blade was submerged while the handle was cast in place. Although the thermal expansion coefficient is quite a bit different between steel and aluminum this did not seem to cause any problems with gaps or anything loose between the tang and the handle. Admittedly, my way of doing things was probably not the best way, nor the safest, but it did work. The potential for injury is very high if a small amount of water gets into molten metal. If a small amount of molten metal gets into a large amount of water it's not as much of an issue, but I was flirting with disaster with that setup. I just want to be clear that I am not suggesting anyone else try to replicate what I did. There are other ways to protect the temper of the blade that aren't as dangerous. Most of the guards I make now are stainless and I affix them after heat treating with a low temperature solder. Heating from the tang side and the use of a heat sink on the blade side does a good job of protecting the temper. Like Billy indicated, "clean, clean, and clean." For me stainless is harder to solder than carbon steel or brass. I think silver should be similar to brass as far as the ease of getting a good bond between the metals.

I believe Steve is correct about what that material is called. My wife buys a lot of my scales, and she said she got those through Amazon and the brand name/seller is xxxxxxx.

A really strong magnet can also create a problem when using a steel flat platen on a belt grinder. I'm planning on switching my flat platen to non-magnetic stainless one of these days since I do like my strong magnets when grinding.

Just for general purposes I think you can use watts per square unit of surface area and watts per cubic unit of volume to get you in the ball park. Again this will not be precise, but if you know the stats on a commercially produced oven and the approximate time needed to achieve a specified temperature then you can make some rough guesstimates. More watts per surface area unit and volume should result in less time needed to achieve a given temperature if we assume that the oven will be insulated at least as well as the commercially produced product. When I was building my oven I asked someone on here to let me know how long it took for their 220v commercially made oven to reach a specific temperature - and it was something close to the max temp you listed. If I recall correctly it was over 2 hours. If you are interested in my ramblings and some responses I got on this forum, you can view those here: https://www.iforgeiron.com/topic/59936-electric-heat-treatment-furnace/'

That seems unreasonably fast to me. However, my experience is with an electric oven I built for heat treatment, so the dimensions are significantly different than they would be for a kiln. Mine is constructed from insulating fire brick for the main body, and that is surrounded by a few inches of packed rockwool insulation, so it is well insulated. If I take it up to the top temp you listed here it would take around 3 hours, but it would still be too hot to put your hand in 24 hours after being shut down. I built mine to run on 110v though, so a 220v machine should heat up significantly faster. I have a hard time believing the 25 minutes for that temp unless the chamber is really small, he's pulling something like 50 amps, and he's using heating elements that will have a short life in that kind of service. I don't think there will be any simple formula that will help you here. Size, shape, insulation, heating elements (and their placement), current draw, etc. will all play a part in how quickly it heats up and how well it retains that heat.

Thanks for the info. I've been lining the mold surfaces with plastic packing tape and then coating that with non-stick cooking spray. I've been getting good results that way. I looked up the teflon rods, but for me they'd be cost prohibitive for the number and diameter of holes I'll be using. Tiny wooden dowels coated with petroleum jelly pull out fairly well though, so I'll probably go that route.

Nice work! If you mentioned it above I missed it, but what material did you use for casting the burner blocks? I bought some Tabcast 94 a while ago with intentions to use it for casting burner blocks but haven't gotten around to it yet. If you or anyone else has experience with that material for that application I'm really interested in the results.

If just for decoration it's not a problem at all. Clamp the 2 pieces to a board or something else flat that you can't weld to in the position you want to weld them. Then use a grinder, file, etc. to cut a channel at the break so when you weld it you are filling in the channel. Smooth out the weld then flip it and do the same thing on the other side. Afterwards it's best to get the weld and the area near the weld back up around critical at least once with a slow cool afterwards (if you intend to use the piece) to eliminate the brittle effect in the heat affected zone that often accompanies a weld. That method may be ok for using the knife as well, but personally I don't like short welds perpendicular to the piece if I want durability. When I electric weld a tang on to a pattern-welded blade I will normally cut out a slot on one side and make a "tongue" on the other side that fits the slot. This gives a much longer weld seam and it decreases the chance of a weak spot straight across the tang. I then use the method described above for welding and usually I do some additional forging to refine the shape before the rough grind prior to quenching. So far I've never had a tang fail using that method, but I'm normally doing that method with full tangs rather than hidden tangs. In your case I would probably cut the slot on the blade portion and then create a new piece for the tang to fit in the slot for welding. Of course you'll have to repeat the heat treatment if you do that.