Stainless steel vertical forge build.... w/pics and regular updates

Half the battle is not being afraid to start something. You have done this, and shown some good ingenuity and knowledge. Like Rick said, even if this doesn't work for heat treating it will work great for forging. With your knowledge,enterprising skills and access to the necessary tools and equipment a heat treat oven should be well within your capability.
 
Your's will be a superb forge, and will do a great job in any forging task from a necker to a katana. You can make damascus billets in it, too.
HT requires very even heating and control of that heat.

Adding a box tube to the top of the chamber as suggested won't really work, as it will go across the chamber, and still have gradients.
It would also limit the blade size to a very, very, short knife.

A horizontal forge will allow a better evenness of heat, and with a good thick refractory lining can be held to a pretty close temperature.
A muffle tube works well in a 12" horizontal forge, but if you used an 8" pipe and 2" wool, plus the refractory, the chamber will only be 3", so I would just make the floor flat, and set the knife in once the forge was fully heat soaked ( 15 minutes running time). Two smaller burners are a good idea if a HT forge will be longer than 14". In a HT forge, it isn't how hot the burners can run, it is how even they can heat the forge to 1500-1600°. 3/4" blown burners or a manifold with several burner ports, are/is very simple to make.
Such a forge is a good candidate for PID control. See the PID Controlled Forge sticky.



Now, if you really want to do simple HT in that forge, here is what I did on a 16" tall, 12" wide vertical forge I built for a friend. IIRC, I may have posted some photos a few years back, so I'll look for them later on. With the ends in place, it was about a 12" chamber depth and about 7" chamber width. The ports were as yours is made, but I do not put a shelf all the way across. I just have the ledge at the port going in to match the refractory depth.

I made two tops.
One with a centered 1/2" stainless pipe sticking out 1.5" on the inside, with the inside end closed. It was placed so it still allowed clearance for the blade to go in and out without being in the way, but could read the temperature of the chamber at the approximate place where the blade was being heated. This TC isn't really necessary for forging, but since the forge was PID controlled, it was there. The 1/2" pipe stuck out about 4" on the outside. This was the top for forging, and the TC was stuck down the pipe, sitting solidly against the closed end. The open end of the pipe was packed with K-wool around the TC to hold in heat for a better reading. Of course, the TC leads had the ceramic spacers on them.

Then I made a second top, with a 2.5" piece of heavy walled stainless pipe that extended to within 1/2" of the forge bottom. The bottom of this tube had a disc welded on it to close the tube. This was the HT top. It had a plug made from fire brick to fit the top of the tube, which was flush with the outside of the top. Both were built exactly like the one you are doing otherwise ( except they had tabs instead of a hinge). In doing HT, the TC was placed in the tube about half way down. The TC wire leads were bent at the top so it stayed at that depth. It was held there by the fire brick cap, which was notched to fit it. After the forge came up to heat ( PID control), and was at the target temp for ten or fifteen minutes, the cap was removed, and the blade was lowered in the tube . There is a piece of 16 gauge stainless wire twisted through the tang hole to lift it by. Bend this wire at 90° at the top to hold the blade just shy of the bottom of the HT tube. The plug was replaced, and once the temp was back to target the timer was set. When ready for quench, the cap was lifted and the blade withdrawn and quenched by grabbing the wire with gloved hands or short HT tongs/pliers. There is no problem with the blade sitting against the TC in the tube if that happens...actuially, that would be a good thing.

This system only allowed 7-10" length blades to be done, but that was all the person needed it for.
 
I've got to chime in about how important the thermal mass is. At school in my metals and manufacturing class, we were heat treating our center punches in the forge(right next to the foundry :) wooohoo). The forge is very easy to use, you press a green button to start it, red to stop the flame. Things sounds like a jet engine, especially when you close both doors and there's only cracks and a small hole for the gas to escape (and heat). But the main cylinder is about the size of a minikeg and it has TONS of thermal mass. There's ceramic all on the side about two inches thick, the doors have like 3 inches on them, and there's two 4 inch tall bricks in the center. Because it has a temperature gauge, you can actually see it heating up(And the bricks, those suckers glow red after a few minutes). After 7 or 8 minutes the center punches were yellow(unfortunately no one knows anything about heat treating there, we only quenched in like 1/3 gallon of motor oil, file still bit it, but only a really small amount), so were turned it off, checked the temp at it was at 1600 something! There's no way you could get that without all the thermal mass. A few minutes after we turned it off, it only dropped maybe 50 degrees.

Sorry bout jacking this thread a little. I asked my teacher if I could do my knife(kinda crazy because I live in a suburb next to a large city) in there and he said sure. He said that lots of other people have done a knife in it. Just a question, if I quench after hitting a little about non magnetic on my 1084 steel, would it matter if I started tempering two hours later? I was going to normalize a few times before I harden it, if that helps.
 
sintro said:
I've got to chime in about how important the thermal mass is. ...... so were turned it off, checked the temp at it was at 1600 something! There's no way you could get that without all the thermal mass. A few minutes after we turned it off, it only dropped maybe 50 degrees.
Click to expand...
Thermal mass has little to do with how hot a forge/oven can get. My simple forge easily gets to welding temperature in minutes. It is important for stabilizing temperature, though.

sintro said:
Sorry bout jacking this thread a little. I asked my teacher if I could do my knife(kinda crazy because I live in a suburb next to a large city) in there and he said sure. He said that lots of other people have done a knife in it. Just a question, if I quench after hitting a little about non magnetic on my 1084 steel, would it matter if I started tempering two hours later? I was going to normalize a few times before I harden it, if that helps.
Click to expand...
1084 is almost a perfect eutectoid. It is among the few readily available steels that responds well to the "forge and a magnet" method of heat treat. You don't need to make a mad dash for the tempering oven but I wouldn't leave it too long.
 
Yeah I should've explained more. I just think it'd be a waste of money (in fuel) if someone was to just use a steel container no insulation or thermal mass because there would be no trapped heat. Maybe I'll try seeing if I can heat treat after school, then head home.
 
So I fired up the forge a few times today. At a lower temp, then higher. Cement dried up with no cracks at all. I am waiting on the ITC 100 to come in the mail to finish it out. A few things I noticed..... First, if I was worried that my one torch wasn't going to be enough, I am not worried any more. The torch I made can heat this thing up to heat treating temps at only about 25% of its max output. The biggest problem is how much flame blows out of the ports when its turned up. Is that normal? I can easily turn it back down when the forge gets up to temp, but most of the vids I have seen of forges don't have flames blowing out of the openings like this. When I open the lid, I can see the flame swirling around inside beautifully. I didn't look into it from the top at full throttle for obvious reasons(I like my hair the way it is), but I wonder if maybe I need to change the angle of the torch. The entire forge was cool to the touch after running for 10 minutes, except the lid was slightly warm (I think because of the hinge that is exposed to direct flames coming out of the rear port. Should I maybe put a hinged door on the back port? I know this thing will heat up a blade in no time, but if I close the back port, it will probably cause more of the flame to come out the front. Then it may be hard for me to get my blade out without losing a little hair on my arm. I'll take a pic tomorrow of what it looks like when the torch is at full throttle. One more question.....if anyone knows, how much time should I be getting out of a propane cylinder (BBQ grill size, 15-17 lbs.) Because I think I only got about 1 1/2 hours out of a full tank heat treating a total of 4 blades in my old firebrick forge, and testing this new forge out.
 
You mention "torch", rather than "burner".

It sounds, from your description, like you are running very rich. This will give a low-temperature flame in the enclosed forge and lots of dragons breath.

I assume you are using an off-the-shelf gas torch as your burner.

Most torches are designed to work in free air. Part of the air required for combustion is usually drawn in and mixed with the gas prior to the flame, giving the central cone of the flame, with the remainder mixing in as the partially-burned gases from the central cone meet ambient air and burn as a diffusion flame; the bushy outer part of the flame.

What is needed in a gas forge is a way to provide enough primary air (the air that mixes before the flame) to work without secondary air. The secondary air can only reach the partially-burned gases from the primary burn once they hit ambient air. The secondary flame therefore becomes the "dragons breath".

The amount of primary air, or more correctly the ratio of air to fuel, actually controls the flame temperature.

To do any sort of justice to the forge, you will need a "proper" burner. The choices are basically blown or Naturally-Aspirated. Each has its advantages and disadvantages, so do some research before making a decision. If you go the NA route, my limited experience is that a Venturi design offers much greater control over temperature than does the "upwind" design. Unless you want to make burner design your hobby, take an established design (Ron Reil, Rex Price and Michael Porter spring to mind) and build EXACTLY to that design. Don't try to "improve" it and don't try to substitute what you have for what the design calls out. Also, do not mix-and-match parts of one design with parts of another.

If you want to engineer your own, a blown burner is much more tolerant of deviation from the "ideal" design. I've used a couple and seen others, but not built one myself.

In your shoes, I'd probably build an all-stainless burner to the Mike Porter design.
 
I've built vertical welding forges with both venturi and blown burners, for this type of forge I'd recommend a blown burner. As mentioned above, sounds like you are running fuel rich. 1.5 hours is way too little time to get out of a full 5 gal. tank. I get probably four times that at heat treating heats, and maybe twice that at welding heat.

Build a burner! Your awesome stainless forge deserves one. Wait, you said "the torch I made"- are you referring to having built some kind of burner? Can we see that, too?
 
One of the great things about a properly made forge is that once it is fully soaked and the refractory is up to the desired temp, it takes very little flame to maintain it. Most people have the torch running at way too big of a flame, when all they need is enough to keep the forge lining hot. The excess gets blown out the ports. Blown burners are far easier to build and to adjust than venturi burners.

I always can tell that a person is burning half (or more) of their propane outside the forge when they say, "My forge will heat a bar of steel to red hot in sixty seconds from a cold start. The forge isn't heating anything, it is just the huge flame heating the bar. The other clue is the sound of a jet plane trying to take off. Obviously, a large "dragon's Breath" flame shooting out the ports indicates way too much fuel pressure. A well running and properly soaked forge does not make a huge noise under normal forging and HT conditions. If the forge is brought up to temp over ten or fifteen minutes, the gas can be cut way back to maintain that temp. Then, the FORGE is supplying the heat by radiation from the refractory layer of the lining. This is much more even and avoids hot spots and overheating the blade (especially the tip and edge).
 
OK, So what I am doing then is using way more then is necessary. When I have the plate completely open on the backside of the burner, I get a perfect looking flame using probably only about 10% of my possible propane output. As I turn up the fuel pressure, I can see the flame starts to turn to a bright white, and then the flames start to come out the ports (dragons breath?) Thats when it starts to sound like a jet plane. Heres a link to a vid of the burner running on youtube:
http://www.youtube.com/watch?v=eTZ9EF_bdIE&feature=youtu.be
TimmGunn, I did make my own burner, venturi type, with 1 1/2" concentric reducers on each end. Here are the pics:
photo12_zpsaa9beb20.jpg

photo13_zps7513a4e3.jpg

photo11_zps20ec7fb9.jpg
 
What PSI are your running? You should be getting way more run time out of a 20lb tank. I get about 7-10hrs per tank, with a range of .5 to 10 PSI. I understand that blown burners get even better mileage.
 
Rick, don't scold me for this, but I don't have a regulator. I have just been adjusting the flame with a valve. I turn it up till it looks about where I want it. I know, wrong way. I am going to get one, along with something to monitor chamber temps. I said this before, I am probably moving faster then my knowledge. I'm the "hands on" type of learner.
 
Now THAT is a problem. Get yourself a regulator! You can get those red Fisher-type adjustable regs now for like $30 or so, add a gauge if not already there, and a ball valve after the reg. Or, your needle valve.

You can use an old acetylene regulator if you have a non-leaky one to hand.

Nice burner by the way, I believe I recall you having posted that here recently.
 
It is a really, really, really bad idea to run a burner without a regulator.


Did I mention it is a bad idea.


Please get a regulator before you fire it up again.
 
Woah.... didn't expect that one. Yes, please get a regulator. My weed burner(used for yardwork only) runs for a couple hours on a tank. It all makes sense now. I should have put 2 and 2 together to get 5.:p
 
OK, so heres another one. This one may make you all really upset with me. So I read all these posts about using satanite and then coating it with itc 100. So, wiseguy I am, I look for satanite on mcmaster carr and find a cement thats rated to 5000 degrees. Well beyond satanite. So I layed in my ceramic blanket, mixed up the cement and poured it. Turned out quiet nice. A good thick solid coating. Problem is, after running it to temp last night, I just checked it to see how it looked (to see if its ready to be coated with the ITC) and the cement is turning to dust. Literally crumbling to dust. Seriously? So I went much deeper into some research on this stuff I used. Turns out its a fire barrier thats good for preventing fire from damaging anything important in a furnace or high temp setting. Not really a refractory. I feel like a real ahole. Fortunately, it looks like I will be able to just break the stuff up and recoat over the ceramic blanket with the stuff I should have used in the first place. So to make a long story short, it won't be getting fired up again for a while. Not until I get some satanite and a regulator. Shame on me.
 
Well, live and learn! At least you found out that stuff was crumbling out before you put an expensive layer of ITC-100 over it.
 
Ha! Just look at it this way... If you aren't making mistakes, you aren't advancing. You probably learned more by trial and error, than most would by blindly following some internet recipe for success.
 
Although it can be frustrating, half the reward of making your own equipment is the learning, the other half being getting what YOU want at a decent cost. You already have way more and know way more about burners and forges than you did a few weeks ago when you started asking questions about your pile of bricks and poor burner.
 
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