I switched to coal a few years back but i enjoy reading about builds sometimes. 

Anyway, you guys may get a chuckle out of this. My gasser was a single burner firebrick box. The burner was a Ron Reil (spelling?) style burner. The jet was a burner jet from an old propane grill, cobbled together plumbing fixtures, very inefficient but i could get welding temps. The box was made of angle iron with a piece of flat bar welded on. The burner hung from the flat bar on a piece of wire going in sideways.  

Billy, I started with coal but had to switch when I moved into my current shop space. My first propane forge followed the Essential Craftsman design, and the burner I was running it with was cobbled out of plumbing parts following some random YouTube video. I did not do a good job building the burner. The jet was way out of alignment, the flare was just a plumbing reducer and the brick box it went into was just as bad. The entire setup was so inefficient that even with this 3/4 burner pegged on the regulator I was only just creeping into welding heats by the time my tank frosted over. But it heated steel, and that was good enough until it wasn't.

On my next forge I used 2" kaowool, some refractory cement as a flame face and a new differently bad burner pointed right at the floor straight up and down. I wish I had found this forum before I built that one. After I found the forum, I blitzed through the NARB thread and Forges 101, and re-did the flame face in Kastolite, built a 3/4 Frosty T powered NARB and that is my current setup. But as I posted at the beginning, it just doesn't quite get hot enough for me to be happy with it.

 

So far, I've built the new forge with just sheet metal and pop rivets, so I think I'll try to continue the theme. I've got an Idea kicking around in my head of using 2  pieces of bent sheet metal riveted together and some bailing wire to affix the burners to the shell. Once the forge has another day to cure, I'll mock it up to see if it'll work.

OUCH, the essential craftsman forge and burner is straight out of a book from 30+ years ago.

I had higher hopes for NARB but it mostly makes even heat rather than HIGH heat. Save it for heat treating.

You'll want something better than baling wire to mount the burners. They don't need to be (welded solid) mounts but they do need to resist movement or falling off. Having a lit torch rolling around on the bench  is a B A D N E S S THING.

Below is a club, clinic burner and forge build. The firebrick is Morgan K-26 insulating firebrick. it's powered by a 1/2" T burner with thread protector step flares. The door baffles would've been K-26 but they were special order and like al projects planned by committee there were a lot of WTFs? in the finished forges.

Just for reference the volume was around 170 cu" and the forge in the picture has burning for less than 5 minutes. I don't recall but the cost was about $100 including the propane regulator and hose. The club got a great break when we bought 30.

We kiln washed them with a zirconium ceramic product located and purchased by the same guy who got the regs.

Frosty The Lucky.

For all I complain about it now, that brick box probably wasn't at fault, I think I built it around 2019? So I didn't have any of the fancy new k26 bricks, just the old fashioned high alumina soft bricks. Knowing what I know now, a well built 3/4 burner should have absolutely been able to bring it to heat. I'm going to blame poor burner design. It looked broadly similar to one of yours, Frosty, but instead of using a... well. I could go on but I figure I'll spare us both the time. 

As for the NARB forge, I think if I replaced the firebrick floor, I might be able to squeeze some more performance out of it. But for what it is, it works fine for the moment.

The bailing wire... I feel like perhaps I could have worded my idea better. The bailing wire could be replaced with a small hose clamp if I cut a slot instead of a hole. The bracket will be held to the forge with 6 pop rivets.

I've drawn a picture for the general idea, hope it makes sense.

Like I said, if it doesn't feel sturdy enough, I'll do something else. 

Plain light firebrick is NOT high alumina, that's why flux dissolves it like hot water on a sugar cube and they break up after a couple firings. The old ones are rated for about 1,500f. My old too large shop forge literally melted them.

Morgan Thermal Ceramics has been around for maybe a century and the K-26 has been industry standard for a couple decades, they're actually THINK I have a few in a box in the shop if you want.

Lose the firebrick on the forge floor. PERIOD! All a firebrick in a propane forge does is take up a gallon of propane to heat to forging temperature and make a nasty gooey mess if you get a borax based welding flux in it. 

That's a pretty fancy burner mount, I kind of like it even though I'd use my old stand buys. Tinkering and messing with metal just because is very Blacksmitherly

Frosty The Lucky.

The bricks I bought claimed to be rated for 2500f with alumina in the refractory, and they seemed to hold up okay against Flux- not that I used much because the forge didn't get quite hot enough to do anything that needed the stuff. The real problem I've had with these bricks is they just fall apart after a while.

I have been planning on replacing the floor in that forge since I read through Forges 101, just didn't have the wool. I bought extra when I started this build with that in mind. And yeah. It takes a LONG time to heat up. 

Thanks for the offer of the bricks, but ever since I saw somone (Another FrankenBurner?) mention making their own with some wool and kastolite I've been itching to try it. But if that doesn't work out I'll take you up on that offer if it's still open.

Who claimed they were rated to 2,500f and having "alumina" in them doesn't mean much of anything. High alumina has very little chemistry in common with standard fire brick. Even though they're fragile they don't break up with thermal cycling. 

Next time try a furnace supply / repair service. If they don't sell them they will know who does. I'm thinking you got snookered or the guy you bought them from just didn't know.

You're changing too many things instead of fixing one at  a time. The length of time and number of steps increase exponentially building, trouble shooting, etc. problem solving in general. 

Frosty The Lucky.

Ah, I'm not changing much of anything at the moment. The bricks I got were from the Jungle River site years ago. They still sell them but since then I've found a spot in Minneapolis that has had everything I needed on hand.  I don't think they carry Morgan Thermal Ceramics, but they might have something comparable, or know someone who does.

I'm going to finish up this current forge build before hunting for new projects. My NARB forge isn't getting a new floor until this new forge is burning nice and HOT with the kinks worked out.

You might even say the NARB forge is on the back burner for now. Ha!

Morgan's high heat insulating bricks came out just a few years ago, and they were a revelation when the did. However, you can find their equivalent in high thermal rated insulating bricks from several sources these days. Look into bricks being used for pizza ovens, to find what you need locally.

It's been a few days, the kastolite has cured nicely and it's time to move this project along. I'm going to do more showing than telling here because who wants to listen to me ramble when there are pictures to look at? 

What is a forge without a heat source? Just a weird box. The first thing was to build a mount for the burners.

Next I had to give it some support so it would quit rocking around on my bench. These rails have a little tab that was bent round on the bottom side to form feet. No pictures of that done, sorry.

These rails are both feet and a support for the hearth front and rear. The hearth is some of what is left of my old brick pile forge.

And here she is after driving out all the moisture.

No pictures of the flames in a cold forge yet. This was the first firing, so there was a lot of orange from the refractory until it warmed up.

A couple things I noticed:

The burners do not burn evenly. That is to say, the far one in the pictures far out performs the near one, like its getting more gas. Any advise for evening them out? Maybe just getting them both tuned right will do it?

Speaking of, I know it's darn near impossible to see in a hot forge, but I'm pretty sure they're either running lean or inducing a lot of air around the ports. Those flames looked pretty purple to me. I'll take some pics tomorrow in a cold forge.

A second note, never mind my 'doors' I've got real ones planned.

I'm pretty excited, I tell you what!  My fancy Infra-red thermometer said 2440⁰F and it's not even properly tuned yet!

 

 

Your thermometer is in the ballpark; I figured the forge to be about 2450 ⁰F just from its high yellow incandescence, before I even read what you wrote about temperature readings.

As to the worry about too much secondary air; that will strictly depend on how much larger the burner portal diameters are than the flame retention nozzle diameters. However, I don't think the forge would be heating anywhere near as well as it obviously is doing, if secondary air was a problem.

As to fine tuning your burners; those are Frosty burners, and therefore I will bow his expertise about anything regarding them.

Mikey, thanks for the reassurance on the secondary air, I definitely agree with your assessment on that, now that I've run it some more. The burners have about 1/16 most of the way around maybe up to 1/8 in spots. I actually might stuff a small amount of wool around them because I was seeing some small flames shooting back towards the inducers and I can't imagine that's good.

I did some tuning and answered the uneven burner question, they burn much closer now. Still different, but I doubt I'll ever get them identical, seeing as they are hand made, and the ports are slightly different.

This is after my preliminary tuning:

This is after the kiln wash was applied and the forge warmed up just a bit:

Just for fun, I held some bailing wire in the burner flame and melted it off, so that's cool... or Hot rather.

It goes against my grain to suggest that you move your burner nozzles closer to the forge interior. We all spend considerable time advising people to push them deeper; not shallower. However, You may want to try moving them closer to the interior openings, just to see if there is some interference with their flames from irregularities in the shapes of the burner openings. You can always move them back deeper. If the flames improve, does this mean they were too deep? Maybe, but it is more likely that the openings should be improved by sanding. Just a thought.

As too the problem of heating from interior atmosphere, it comes up fairly frequently, and must be tinkered with, case by case. I would love to tell you what is going on for sure and certain. Alas, Mikey don't know (gasp!) 

Twenty-six years thinking about this subject, and still there are things I just don't know...

Maybe Frosty does.

It has been about a week and I have finished my doors and some additional experiments. I noticed that a lot of the doors on internet forge builds follow either one of two routes: the first being a mobile baffle of some sort. The simplest of this style is a simple fire brick that can be move out of the way, while the most complicated involves some sort of captured refractory and a lift mechanism involving cables and counterweight.

The second is a hinged door of some sort. There are several paths down this fork as well, those being the different ways of hinging a door along a different axis: The x-axis being more like an oven door or a tailgate on a car, the y-axis like a cabinet or house door, and the final z-axis, like a lift gate for a train crossing.

I like the simplicity of a mobile baffle like a fire brick, but I'm clumsy and have dropped multiple HOT fire bricks to shatter on the floor. So how do I make a mobile baffle that cannot be dropped on the floor? Simple: attach it to the forge shell as a door. I decided on the final option, the z-axis door, as that allows me to close the door on items in place on top of the hearth. Not to put too fine a point on it, here is a picture of the finished doors:

I didn't want any metal exposed directly to forge atmosphere except for what I am heating for a beating. So this is what I ended with, anchors cast into refractory, tacked to a hinge/handle arrangement.

These doors are not solid kastolite. I mentioned in a previous post being intrigued by the idea of making "fire bricks" with a core of ceramic wool, so that is what I did. I encapsulated a rigidized wool core with kastolite poured around it, leaving a hole poked through to the core for moisture to escape from. I have no interest in destroying my work by superheating steam in a closed structure.

Picture of my "mold":

I cut and taped a cereal box into shape and lined it with some plastic wrap to keep the kasolite contained. Not shown in this picture is the hole I poked in between the anchors for steam to escape, kept open with a coffe stir straw into the wool. I put these in a bag and left them to cure for most of a week warm and wet for the best strength.

And here is the hole in action venting steam:

Over all, I'm very happy with these doors. I didn't take any pictures of the "working" side of the hinge because it's dead simple, just a strip of steel bent into a barrel for the 7/16 rod to rotate in. They are adjustable for depth too, so I can make the opening between the doors and the forge bigger if I need to for the forge gasses to escape.

 

Now for the additional experiments mentioned at the top of the post. With my infrared thermometer I recorded a peak temperature of 2706⁰F. This not likely entirely accurate because the refractory index for ceramic is slightly different than what the thermometer is set for, but it should be close enough for this.

It turned one of my modified nozzles that Frosty disliked so much into a nice puddle on the floor in probably less than 5 minutes. It's cast iron, so the melting point is lower than pure iron because of the high carbon content, but I noticed the color of the forge turn towards white once it started melting. I think the reason for the temperature increase is because the forge was burning off the dissolved carbon in the part. If anyone has ideas about this I'd like to hear them, for curiosity sake if nothing else.

I've done a few successful forge welds but none without flux. The forge does have an oxidizing atmosphere that adjusting the burner jet does not seem to affect. The only change I noticed was a shortening of the flame compared to my control burner. Substituting a 0.8mm 3d printer nozzle made the flame rich to the point of safety concerns. So in this case, I'll keep with the 0.6mm jet adjusted how it was before I messed with it.

Mikey, the burners seem to behave best with the back of my coupling just inside the forge shell. With the burners further out from the forge interior, the flames seemed almost trapped in the ports, but too close and the burners would just blow the flames off the couplings. I sanded the ports a bit, but I didn't notice any improvement in burner characteristics.

The space around the burners does not seem to be inducing any air. I used some HVAC foil tape to temporarily block off any air bypassing the nozzle into the burner port and noticed no change in flame color or behavior.

 

Voltaire said, "perfect is the enemy of good" I have actually achieved everything I initially set out to do when I started, so anything more gained is just icing on the cake. That's not to say I won't keep tinkering, just that even if nothing I do makes it better, it's still pretty darn good.  So thanks to everyone that helped me get here, specifically a big thanks to Frosty for dealing with my silly burner mistakes, and Mikey for his freely shared knowledge on forge design.

Bfancy, your description of your burner depth in the ports sounds almost exactly like mine. Too far back and they burn inside the port, and it glows incandescent before the rest of the forge is up to temperature. Too close to the interior and they are burning out from the end of the port entry. I think I'm the same as you, where the atmosphere is just slightly oxidising but still very hot and I can forge weld with flux. 

I like your door, but may I offer one possible improvement. Where your hinge rod bends towards the door, if you were to attach an arm the other way, in a "T" configuration, with a similar weight to the door, you would have a counterweighted door that would balance and remain at whatever height you open it to, while still being very easy to move. 

Let me know if my description doesn't make sense and I could try a sketch for you.

Cheers,

Jono.

Ben, really nice job on the forge along with your conversational descriptions and pics. Noting your appreciation of Frosty's assistance, I'd say your forge rather unintentionally wound up being a nice tribute to him as he passed away the other day. Well done sir.

 

--Larry

On 1/17/2026 at 5:00 PM, BFancy said:

So thanks to everyone that helped me get here, specifically a big thanks to Frosty for dealing with my silly burner mistakes, and Mikey for his freely shared knowledge on forge design.

You're welcome. But how sad it is to here that Frosty is gone

The Z axis is a fine choice for a forge door; it is simple and effective.

 I'm assuming that your pair of Frosty burners are 1/2"?

Mikey

I didn't expect the kind of grief I'd feel for a man I hardly knew. I wish I could have known him better.

Mikey, my burners are a pair of 3/8 Frosty burners running with 0.6 mm 3d printer jet. I honestly expected to be able to turn them down much further than I can without them huffing. I have an idea about the normal Frosty T ratios that I might like to test once I have some time to tinker. I'll go into a bit more detail in a minute.

Hefty, what size burners are you running on your forge? If they are the same size as mine I've got an idea about that lean mixture. As for the counterweight on the doors, I believe I know exactly what you are talking about. I might mess about with that in the future, but for now, the doors are not very heavy, so lifting them is pretty easy with my poker.

Alright, the idea I've had is that the Frosty T burner plans use the 3/4" burner as an example and call for a 1" T with a 3/4" branch. The 1/2" inch burner uses 3/4" intakes. The smaller we go in size, the bigger the inducer intakes are in relation to the burner tube.

My burners use a 1/2 x 3/8 x 1/2 T inducer. They run pretty lean in the forge and I'd like to try using a 3/8 x 3/8 x 3/8 T and see how that affects the mixture in the forge, and if that let's me adjust mixture with the jet distance.

I travel for work and won't be able to tinker for probably the next month or so, but I would like to know everyone's thoughts on this.

On 1/7/2026 at 7:32 AM, BFancy said:

So far, I've built the new forge with just sheet metal and pop rivets, so I think I'll try to continue the theme. I've got an Idea kicking around in my head of using 2  pieces of bent sheet metal riveted together and some bailing wire to affix the burners to the shell. Once the forge has another day to cure, I'll mock it up to see if it'll work.

There is nothing wrong with that idea. You would be smart to look at how Diamondback Forges has changed their original design; the first one was good, but the new forge bodies are even better, and are well worth imitating. Also, you would be ahead to replace the choice of pop-rivets with machine screws, to hold the new forge body parts; screws are more work, but allow you easy access for internal changes and/or repairs...just a thought.

20 hours ago, BFancy said:

My burners use a 1/2 x 3/8 x 1/2 T inducer. They run pretty lean in the forge and I'd like to try using a 3/8 x 3/8 x 3/8 T and see how that affects the mixture in the forge, and if that let's me adjust mixture with the jet distance.

This is the opposite of my original problem. I originally had 3/4x3/4x3/4 tees (all I could get at the time) and it was running richer than I realised and robbing me of potential heat, meaning I was always turning them way up and using up gas. I switched to the specified 1x3/4x1 and now they seem just a little too lean, but one more so than the other and not enough to prevent forge welding. The forge now gets way hotter than it used to, and at way lower pressures.

I'm aware this increases the risk of CO, but I forge under an awning just outside my shed and with both of the doors of the shed open, and I get a good cross breeze for ventilation. The pros of this change still well outweigh the cons for me, but I may still tinker a little as I go.

On most burner designs the main variable between running rich or lean is the gas opening diameter versus mixing tube's inside diameter, and the distance between the end of the gas jet and the forward ends of the mixing tube in Mikey burners, or of the distance to the exit side of air funnels in other designs, matter less. However with Frosty "T" burners the distance between the end of the MIG contact tip and the opening of the air/gas exit is every bit as critical as gas orifice size.