Buzzkill

What are you doing (or planning to do) that requires that much length? For me it's more important to have height and width to accommodate odd shaped pieces. Long pieces can pass through the back of the forge. I rarely need more than 6 to 10 inches of steel heated at a time, but you may be doing something entirely different than I do. As you've indicated, more length means more burners. More burners means more fuel cost - and possibly iced up propane tanks. To determine the number of burners you need to calculate what the forge chamber volume will be after adding all your insulation and refractory. You'll want one 3/4" (well built and tuned) naturally aspirated burner for every 350 cubic inches of volume you have in your forge. If you do install more than one naturally aspirated burner keep in mind that they can interfere with each other, especially if placed too close together. At the intake end they can compete for air if not oriented correctly, and on the flame end the back pressure from one can affect the performance of another. If you have some basic tools and shop skills you can build Frosty's T burners. That's probably the best bang for the buck. Of course it helps that you can discuss any problems you have with the guy who designed the burner here on this site. Here's the link to the topic that has the plans: https://www.iforgeiron.com/topic/43976-t-burner-illustrated-directions/ I don't have any experience purchasing burners off the internet, but maybe someone else here can chime in.

Looking forward to seeing the results. I'm curious how tightly you can control the temperature in the 1900 to 2000 F range.

What are you trying to accomplish by annealing? If all you are trying to do is drill holes in it then there is an easier way. Heat to a little below critical temperature (usually a dull red) and then throw it in the vermiculite. That's more of a high temperature temper rather than annealing, but it should allow you to drill holes. If it doesn't then the carbides are probably the issue and you may have to go the slow route to get what you want. If you are annealing for other purposes that may not be the way to go. Rockwool insulation (at least the stuff I have) is rated up to 1200 F. So, if you want to build an annealing box you could use that to line it, maybe cover it with sheet metal if you think you need it then fill with vermiculite. As long as the glowing steel doesn't come in direct contact with the insulation or the box there shouldn't be a problem. You could do that with kaowool as well. Personally I think coating in refractory is overkill for something like this. I just use a steel 5 gallon bucket (with a removable lid) filled with perlite for this purpose.

Interesting. Usually you see plate quenching with high carbon stainless alloys. As I understand it, the reason is mainly because those alloys need long ramp and soak times that could change the carbon content of the steel if open to the air. Generally these are heated in stainless steel pouches to keep the oxygen from the steel and then plate quenched assisted by air blast from a compressor or something similar. The reasons for plate quenching rather than oil quenching have to do with the finish of the blank and the time it takes to remove the blank from the stainless foil pouch. This seems to be an attempt to avoid warping during an oil quench more than the plate playing a large role in dropping the temperature quickly. If that's the case I wonder if using some heavy expanded metal or something similar might even be better. If I'm quenching a thin blade I will sometimes set up a couple pieces of angle iron in the jaws of a vise so I can slide the blank into place immediately after quenching, tighten the vice and then add a couple c clamps on the ends. Of course I don't know for sure if the blades would have warped or not, but this does seem to keep it to a minimum. Distal tapers running in both directions from the ricasso area complicate things though.

There are a couple potential issues. Yes, you definitely need somewhere for the exhaust gases to escape, but there are other things as well. When you say you want to use it for heat treating, what exactly do you mean? If you want to temper with the system you will find it to be a challenge. The issue will be keeping the temperature low enough. For most gas fueled forges, it is almost impossible to use the same burner to stay at tempering temperatures and also be able to hit quench temperatures or forge welding heat. If you are just planning to use it to reach and hold quench temperatures you can make something like this work. However, you can see in the video when the solenoid kicks off and only the bypass is active, the flame color changes to a purple hue and the flames lift off the burner head. This is because the air supply has not changed at all, but the fuel has. During those times there is an extremely lean flame, which means excess oxygen is entering the forge. That can lead to scale formation inside the forge, and could inhibit forge welding, especially if welding without flux. On the other hand, it does not appear as though he controls the temperature of the forge with the PID when forge welding, so that may not be much of an issue. There are a few ways around the oxidizing flame issue. The easiest is to use a naturally aspirated burner which pulls in the right amount of air with the gas across its entire effective operating range. That way you just need a single solenoid for the gas, and of course a bypass line for the gas like he shows. Since you don't use electricity to aid combustion with a fan, you don't need to worry about the power going out. If the power goes out the solenoid will close and the burner will continue to run on the bypass setting. For a forced air burner there are a couple options. One way is to have a variable speed fan with a separate circuit so that the fan slows down (but does not shut off) when the gas is reduced. Another way is to have yet another solenoid on the air supply and a bypass on the air supply like is on the fuel line so that the correct amount of air is provided on the bypass line for the air to correspond with the gas bypass circuit. You would activate the 2 solenoids with the same control on the PID so that when the gas solenoid is fully open the air solenoid would be fully open as well. Unfortunately, normally closed solenoids in the 2" or larger diameter tend to be pricey. Of course if you aren't concerned with the short bursts of oxidizing flames, you can build as he shows and have a fairly stable fluctuation in temperature probably across a roughly 1300 and 2000 degrees F range, depending on your burner and forge. I have built an electric oven for heat treating. There are some advantages and disadvantages to both. With the electric oven I can temper if I choose to do so. I could even warm dinner without burning it. It can reach about 2000 degrees F as well. Once up to temperature, the fluctuation of temperature is something like 5 degrees as long as the door stays shut. The down side is it takes a long time to reach high temperatures - about 3 hours to hit 1950 degrees F. I built it to run on 110v though, and it would probably cut the time significantly if I was running on 220v at higher amps. It also takes a long time to cool down - half a day or more. With a gas forge I'd expect to see 2000 degrees F in a half hour or less.

For the price they are charging here it's definitely worth it to make your own. I used a piece of barbell for the hammer. It already had a knurled section to aid in getting a good grip. I had a length of thin walled tubing with the needed diameter that was reduced on one end so that it could be nested inside another piece of tubing. After inserting the barbell into the tubing on the reduced end I ran a bead of weld around barbell that protruded from the other end. That prevents the hammer from being removed from the tubing. Lastly I ground a portion of some solid round stock to the right diameter, inserted it into the larger end of the tubing and welded it in place. I used short section I cut off an S cam from a semi trailer, but any medium carbon steel should work fine for the anvil side of the tool. However, there is another alternative that is already closer to what you want. Do a search for "Slide Hammer Tire Bead Breaker." Those tend to be more reasonably priced, longer, and heavier than the slide hammer like the one you showed above. All you would have to do is replace or reshape the end of the tool.

That's a difficult question to answer. That design would have limited appeal for me. The fabrication looks fine, but the dimensions and material thickness are not right for my needs. Without calculating anything I'm guessing it weighs 50 pounds or more. In my opinion even 1/8" thick shell material is overkill. The outside width is about 7.5 inches, (7" interior width) so if we add the typical 2+ inches of insulating blanket and refractory material, we're down to about 3 inches of width in the chamber. If the perimeter is a square then the height is likewise 3 inches or less after adding insulation and refractory. The length is excessive for anything but very specific work, such as decorative twists on long (and straight) stock. When using a hand hammer it is typically difficult to work more than about 6 inches of stock before it needs to go back into the fire. Heating more than that can be wasteful at the least, and repeated re-heating to forge temperatures can actually have a negative impact on steel - especially high carbon steels. There are more burner ports than I would use as well, although the unneeded ones could be ignored when lining and just covered. So, as far as value goes, that depends on the end user. For me it would have little value, but if you could find someone who needs to heat long straight stock it may be worth a bit.

IIRC it was about 240 cu. in. That was 3 forge bodies ago though.

I'm waiting for updates with interest. Vinegar works, but I'd prefer this solution (both meanings) if it is suitable for the task.

Just FYI, if you use DuckDuckGo's browser, they have their own video player. It gets rid of all of the ads on YouTube, and also removes the comments and suggested videos. However, there are some videos it will not play due to some form of copyright issues. Without ad blockers/removers YT is unusable for me. If they ever get to the point where I can't block most of the ads that will be the point I cease using the platform. This formula does look promising. It goes on my list of things to try when I get a chance.

If safety is your main concern I recommend taking a look at oscillating tools. I have a Bosch with variable speed. It certainly works better for some things than others, but since the cutting edge is essentially vibrating rather than spinning there is no real danger of something like the catastrophic failure of a cutting disk or anything getting wrapped up on a spinning shaft. Of course it does require that whatever you are cutting has enough mass or is held stable enough so it doesn't allow the vibrations to be absorbed.

Low pressure is not his issue. If it was a low pressure issue he'd be getting burn back in the mixing tube or similar results. This sounds like blowing the flame off the end of the burner. If it were me I'd be looking at axial alignment of the mig tip and the mixing tube. Just for troubleshooting purposes I'd also cover one of the inlets on the T and then partially cover the other with my hand while trying to light it. If the flame stays on the end of the burner with most of the intake air blocked off, but blows off the end of the burner when you remove your hand then at least you know for sure it's not a low pressure issue. From experience I can say that without a flame retention feature on the end of the mixing tube some T burners are difficult to keep lit until the forge starts glowing. While I don't necessarily recommend a 3/4" to 1 1/4" reducer fitting as a permanent flame retention feature, it can be useful in troubleshooting. Check the easy things first.

Yes, that will be fine as long as it isn't directly exposed to flames - which it shouldn't be. Once it's coated/covered with refractory it should be fine for everything through forge welding temperatures.

I built it. However, I didn't like the noise of the blower (I had a bouncy house blower) and being tied to power, so I didn't use it for long. I went back to a standard T burner until you introduced the NARB to the forum. I've tinkered with a number of variations of NARBs since then, but I don't foresee ever going back to a blown burner or a single port burner. I was trying to figure out how many years ago it was that I used a blown burner based on that progression. It had to be at least 7 years ago now, and I can't tell you the exact dimensions of the design. If I still have notes from that project I'm not sure where I put them. I did (and do) a lot of tinkering with burners, but I have a tendency to toss records of the things I didn't feel turned out well. If I don't do that then I have piles of papers with "bad" designs and over time I forget which ones are worthwhile.

Fair enough. I have limited experience with blown burners, but I don't recall having difficulty getting fairly even flames using a rear mounted inlet and a diffuser. However, I never tried a side mounted inlet on a blown burner, so I can't personally compare the two designs.