Buzzkill

Downright inspirational! May have to give one of these a go when it gets too cold for me to forge outside this winter.

My younger brother requested a dagger. I've never done that before so I opted to use some 3/4 inch coil spring for the stock. I got some practice "uncorkscrewing" a blade in the process, but overall I was fairly pleased with the results. The bevels came out pretty well and I had no deep hammer marks to deal with so cleanup on the grinder was relatively minor. After the rough grind it was time for 3 times of normalizing then quenching. I use my propane forge with a 2.5 inch diameter piece of stainless pipe with one end hammered closed, so no direct flame impingement is possible. Using my trusty magnet I went through my normal routine. Heat to non-magnetic, back in the forge for 30 seconds, then into the oil (which I warmed already by heating and quenching another item). I don't even have to take a full step between the forge and the vertical quench tank I'm using, so there's literally less than a second of time between forge and oil. As usual I grab the file to check for hardness. Surprisingly to me it bit in almost like mild steel. So I heat up the blade again, but a little hotter this time and back into the oil. The file still bites in. One more time and still no joy. So I grab the remaining piece of coil spring used for the blade, heat about 3 to 4 inches to non-magnetic and into the oil. The file slides off like it was glass. I tried quenching the blade one more time in oil and then in my frustration decided to do a water quench. Same result. The file still bites in. A second water quench and the same thing again. With this many quenches it's not surprising that the blade has developed a noticeable warp. Since I'm not getting the blade to harden anyway I decide to straighten the blade cold. Some of you probably already see where this is going. With only moderate force on the blade it snaps the top 3 to 4 inches off cleanly. I decided to make a shorter blade and ground a new tip on it, but leave it until the next day after that. When I checked it the next day there were (not surprisingly since I didn't temper it) cracks near the tang area on both sides of the blade, which of course meant I had to start over. So, I started testing the pieces of the junk blade a little more thoroughly with files. It turns out there was a relatively thin layer of unhardened steel, but below it was fairly well hardened. Of course my first thought was decarb layer, but this had already been through rough grinding after forging. I thought that would remove any decarb layer. I run my forge rich to avoid scaling, which I also though would reduce the chances of that happening. With the pipe in the forge and no direct flame impingement I figured any new decarb layer would be almost non-existent at that point. Anyone got any idea of what was going on or what I should have been doing differently? FWIW, the second blade came out pretty well, but did show the same symptoms after quenching. However, armed with my previously gained experience, I only quenched once and got to the hard stuff quickly. I'll try to get some pics up when I get done with it, whenever that is.

From what I've seen on here if your choices are Kohlswa and almost anything else, you grab the Kohlswa and don't look back. That assumes both are in decent condition and in your price range. Kohlswa vs. unknown would be an even easier decision for me to make. If you have the opportunity to do a side by side rebound test with a ball bearing that would be worthwhile before making your final decision.

Think about this for just a minute. Most of us use 2 to 6 pound hammers to manually strike steel on anvils 100 to 500 pounds in weight. I'm not sure what kind of hand cart you have in mind, but the force created by 25 pounds repeatedly striking downwards needs a solid anvil under it to be effective. That translates into weight and a lot of it. It's hard for me to imagine any power hammer with a 25 pound tup weighing in at less than 1000 pounds total. I believe the minimum suggested tup to anvil ratio is 1 to 10, so the anvil alone should be at least 250. Also, the lighter the whole thing is the more it will want to walk around the floor when in use. I certainly wish you the best of luck here and am interested to see if you can find something that works well and fits your needs, but my optimism level is low on this one.

I've always enjoyed your work Theo, and this is no exception. I like the WIP series of videos too and looking forward to more.

Not trying to nitpick here, but it is exactly the same. The pressure at which propane enters the mixing tube of a blown burner is for all practical purposes irrelevant. The only thing that matters is the volume of gas. No air needs to be induced in a forced air system, so whether you have a 1/2" fuel delivery line at very low pressure or a 0.023" mig tip at much higher pressure, the volume of propane must be the same in either case in order to get the heat you want. I don't recommend it, but you could run the fuel line directly from the propane tank and use only a needle valve to control the volume of fuel. The pressure after the needle valve would be way lower than the tank pressure just like it is with a regulator. The way you have yours set up is the preferred way. It's best not to have full pressure fuel lines anywhere near the forge, and with a gauge you get a visual indicator which helps to easily reproduce preferred settings in the future. The needle valve in the system is really just fine tuning and may help smooth out any pressure pulses from the regulator as the valve inside it opens more or closes more to keep the pressure downstream close to the specified pressure. Both the regulator and the needle valve affect the volume of propane that is flowing to the burner. Both of them will also affect the pressure downstream from them in the system. Again, a regulator is a valve. It just happens to have somewhat automatic features built into it for opening and closing as needed to get the desired result. I wouldn't have bothered responding, but it seems frequently there is confusion about this topic. People ask what pressure they should run at - which I understand. We don't have volume meters on our forges usually, but we typically do have gauges that show the psi. The problem is that what seems like a relatively small difference in systems can cause them to run at significantly different pressures, but the volume of propane needed (at the right air mixture), especially for a blown burner, is really what is important for heat output. In NA systems since the fuel delivery induces the air and mixes the fuel and air at the same time, the diameter of the orifice and the pressure at the orifice become much more important.

Yes, Wayne, but in this context it accomplishes the same thing. You could run your ribbon burner with no regulator and use just the needle valve or vice versa. In simple terms a regulator is just a valve that uses a spring, a diaphragm, and gas pressure, rather than a handle, to determine how much the valve opens. Without knowing how large the gas inlet orifice for your ribbon burner is compared to what it was in your venturi burner, no determination on which uses more volume of propane can be made. One half psi running through a 10 foot diameter pipe is WAY more volume than 500 psi through a 0.025 inch jet for example.

For this purpose the regulator and the needle valve accomplish the same basic function; they restrict the volume of propane supplied to your burner. Since temperature is determined by the amount of propane burned at the right air mixture, both methods should give you the same fuel consumption for a given temperature over time. Typically this type of setup will have an idle pathway for both the air and the fuel which is always open when the forge is in operation and set for about the lowest stable flame possible. In your case you only need one pathway for air if you are able to control the blower speed accurately enough to work at both the idle and high settings. A second fuel pathway with a normally closed solenoid would be opened by your temperature control system, and that same signal should be set to increase your blower output simultaneously. Once you have both the idle and high fuel to air ratios set properly then the PID should cycle the high circuit on and off as needed to keep the forge within a set temperature range. I would run the regulator at a high setting and use the needle valves to set the fuel flow on both the idle and high output fuel circuits. On a safety note, at a minimum you should have a normally closed solenoid in your fuel supply line close to the source, using the same power circuit to open it as powers your blower, so if your blower ever loses power, all fuel going to the forge is immediately cut off. Once a forge is up to temperature there is little chance of a flameout, but there are sensors and circuits that can be used to cut the fuel if a flame is not detected as well.

I know the episode was filmed a while ago, but congratulations on the win, Dave.

Whatcha smelting?

In the Army we always sent the new guys to go get a box of grid squares, a hundred yards of flight line, a package of chem light batteries, and a can of blue squelch (not the red - it's flammable).

Sounds like we need to ban either oxygen or combustion altogether - you know, for the sake of the children.

Grussing, you shouldn't ignore that point. You could give me the best anvil, the most expensive "forging hammer," a forge that can turn steel into a July 4th sparkler, all the tooling you can imagine, and I still couldn't turn out the quality or quantity of forged products that some of the guys on here do in an afternoon when they are just puttering around. If you don't have the combination of knowledge and experience applicable to your task then the tools are only a small part of the equation. I'm not trying to discourage you, but it's entirely possible that you may fail at pattern welding with a given forge when someone else could be successful using your forge and tools. I don't know how you will ever be "110%" sure (and I personally hate the use of 110%) until/unless you have actually done it. Even stating that you want to make sure it can reach forge welding temperatures is not a guarantee, since as Thomas pointed out there are people who seem to be able to forge weld at what appear to be unbelievably low temperatures for doing so.

In broad terms the heat treat of different alloys are similar. Heat just past critical and cool it quickly, then temper the steel to get the desired balance of hardness and toughness. However, depending on the alloy, the critical temperature will be different, as will the speed at which the steel needs to cool. That will determine your method of quenching. Some alloys require very specific temperatures to ramp up and hold for specific amounts of time in order to get the most out of the steel. Some harden by air cooling, some do best with oil, some need a water quench. Whatever you use, the manufacturer will have a spec sheet for the heat treatment for that alloy. If those are followed you will get good results for that alloy. In general terms you can learn how the steel moves under the hammer with mild steel, but when you move to medium or high carbon steel it will not be identical. Some steels are notoriously hard to move under the hammer with a very narrow forging range. Others are more forgiving. The point is you'll need to get used to how the steel you want to use for your finished product moves under the hammer, so practicing on mild steel will only help so much.

I haven't made a knife yet that I'm 100% happy with, but I can tell you that as makers we see far more of the flaws than the general public does. Still, if we don't chase perfection we'll never catch it.

Frosty and Mikey gave you good advice. Spending time reading on here will go a long way towards helping you understand the "why" of certain designs. In that vein, the flap door on the pass-through seems like a good idea, but if you do that make sure you have some way to fasten it up and out of the way. If you just push stock through to open the door it will tend to catch the material when you try to pull it back out and that gets frustrating very quickly. The size thing gets us all at first it seems. I went way too big originally, now I use a freon size tank, and I'm planning on making an even smaller forge. I mainly forge knives, and for most I have done there just isn't any real advantage to going bigger for forging. When it comes time to quench though it is nice to have something long enough to bring the entire blade up to critical. I'm tinkering with an idea to combine two small forge bodies for that purpose, but only use one for forging. Another option is to use a removable insulating wall to change the volume of the forge. Those are some handsome knives you posted as well. In simplest terms the volume of an object is the length times width times height. If using a cylinder shaped chamber you have to find the area of the circle times the length. For "D" shapes you have to modify the calculations a bit more, but still not too tough. The rule of thumb you'll see here is one 3/4 inch inside diameter naturally aspirated burner per 350 cubic inches of forge chamber. It's probably pretty close for blown burners as well, but someone may have better info on that than I do.

It depends on what you mean by "get away with." What you have done should significantly decrease the chances of breathing harmful particles while retaining most of the insulating value of the blanket. However, it will still be somewhat susceptible to damage from pieces of steel rubbing or poking into it. Also without any kind of IR reflective material it won't be as efficient as it could be which means you will probably burn more fuel and may not be able to hit welding temperatures as easily if at all. Without a refractory lining to "hold" some of the heat you may also find that it takes a little longer to bring cold steel up to forging temperature. If you're asking if it will contain heat and not damage your lungs the answer is probably "yes."

You said something about needing a few parts. If it were me it would come down to how much those parts cost. Since you already have it, if it was already in functional shape I'd say fire it up and see how much gas it uses. Whether it's a hog or a miser one forging session is not going to break the bank and you'd get some good data. For the sake of argument if you were going to have to dump another 500 bucks into it in order to do a test run that would be a different story. Like Frosty says you may be able to put a better insulating liner in it, and if the automatic temperature controls work you may end up really liking it. You probably won't know until you try it, but again for me it would come down to the cost to get it functional.

I couldn't see the image you posted, but it sounds like you might be going overkill on this thing. All you need is something that will hold oil to the depth and width (plus a little) you want to harden the tines and possibly part of the shaft. Just off the top of my head, you might be able to get a large muffler with close to the right dimensions. Obviously you'd have to cut one end off, take out the internal stuff, and block the exhaust port on the remaining end, but that should be a much cheaper option if you can find one large enough and you should be able to tack weld it to something for a base.

Maybe I'll try for a new market there with blades called "The Negotiator" or "Pieceful Resolution" or maybe "Undead Lullaby." Think those would pass muster? I'll call the "bumps" on the back of the blades "scalp massagers."

Is there no one who studies history there? Banning a class of weapon merely shifts the activity to involve the use of the next best thing. Maybe if they took a look at how a number of the martial arts weapons gained prominence that would help it sink in. Many were merely repurposed (or dual purposed) farming tools which couldn't be banned if they wanted the farmers to provide them with food. What does it take for people to realize that the person wielding a tool is far more important to the outcome than the tool itself?

If by "shuts off" you mean it blows the flame out that is something that may not happen inside the forge due to back pressure. Tapering your flare (flaring the sleeve) will help with that issue outside the forge though, as will the cast burner block with a ratio of 1:12 or less expansion inside the forge. The relationship of the gas inlet orifice compared to the inside diameter of the burner tube is important. If you have followed the instructions for the burner strictly and those are the tube diameter and bit size specified then that shouldn't be a problem as that is a known burner design. I haven't built one of those specific burners, so I'll defer to someone who has for advice on the orifice size. A cast burner block is literally just a block of castable refractory that you can place in your forge where the burner enters it. It would be surrounded by insulation on all sides and should end up pretty much flush with the interior surface of your forge. It's basically provides a flare on the end of your burner tube and takes the place of a stainless or other flare. It helps with flame stability and if it is cast out of a quality refractory should not deteriorate due to heat as quickly as a steel flare would. It's not required for the burner and forge to function, but it's a nice feature with some benefits if you make one. The only down side to that is it's almost impossible to change the aim of your burner if it's effectively part of the forge's hot face. Based on the dimensions you have you should only require a 3/4" diameter burner and that should be plenty for the forge. Side vs. top mount is a matter of preference. As you show it in the picture when you turn off your burner heat will travel up your burner tube. It doesn't look like you are using any really heat sensitive materials in your burner or the fuel delivery lines close to the forge, so you just have to remember not to touch it after you shut the forge down - or you can remove it immediately after you are done. Some people aim the flame at the floor because the floor tends to be a more durable material for both mechanical and thermal damage compared to the rest of the interior so it can take more abuse from the more or less direct flame impingement. For a side mounted burner, especially in a curved forge, you tend to get more flame swirl, which some argue provides a more even heat and more complete combustion in the chamber. I'm not sure anyone has ever definitively proven that one is "better" than the other, since different factors are at play in each one.

What pressure does this happen at? If you're around 3 psi or lower when this happens it will probably go away by increasing the pressure. If you're already at 5 psi or higher then it may be a design or alignment issue. Also, it's best if you tune the burner where you will be using it. If you try to tune in open air and then put it in the forge you will probably have to tune it again as things like back pressure are different in the forge environment.

Crazy Ivan had a post with lots of pics of his striking anvil. The forum doesn't seem to want me to post the link, but you can look up S7 striking anvil WIP. I just saw that you were the first person who commented in that thread, so obviously you have seen it.

Thanks for the clarification Mikey. I was thinking I'd need a whole bunch of earth moving equipment if we're going to start designing gorges. That aside, thanks for taking the time to do the burner and forge threads. It's always good to see the "why" behind a design.