Thread: Forge insulation question

Originally Posted by Atchbo

Got the tank cut open and almost ready for the insulation. Thinking about locating the burner at 12 o'clock... Any major problems with this approach?

Probably not, though a lot of designs mount the burner at an angle close to the tangent of the inner diameter to promote a swirl effect and more evenly heat the walls of the forge. Remember to close the air ports of your burner when you shut down the forge to prevent it acting like a chimney and fowling the orifice.

Originally Posted by Atchbo

Got the tank cut open and almost ready for the insulation. Thinking about locating the burner at 12 o'clock... Any major problems with this approach?

Yes, heat rising up into, or around, the burner arrangement can have an effect on performance. For a venturi style burner, I'd recommend bringing the burner in from the side, at or below horizontal. There are also those who suggest that preheating things makes them operate better. My experience is more practical. If there is a problem with the burner, say a side flame/gas leak not so large as to be "interesting" you have to reach into the burning stuff to shut off the needle valves and snuff the problem. With a burner from below or to the side, all the fiery nonsense is rising away from you and you can approach the problem from a safer perspective. YMMV.

I'll locate a cutoff away from the burner itself, and will consider the lower-than-horizontal angle. Isn't that harder on the wall/insulation?

I will test fire the burner tomorrow, when my regulator and hose arrive. Might need a few more parts and tweaks just on the burner (haven't built the choke yet). I hesitate to build anything that is both metal and airtight behind/beside the gas nozzle. I may use a flap disc that rotates into/out of the way, but that is thin enough to give way in case of 'hiccups'.

I want to reinforce the bluesman's variable: some of these forge designs are assembled so that the burner blows straight across the diameter of the tube. This will produce localized hot spots and can wear out the liner earlier than necessary. I recommend aligning the burner so that it enters the forge on a tangent and swirls the flame around the inside. The forge heats faster and it reduces the hot spot problem and early replacement of the liner.

But, there are a bunch of ways that people build forges and they will all get metal hot for the most part.

I think I'll weld the burner holder tube at a tangent... I like the idea of the top-down burner beating against a fire brick rather than the forge lining (even at a tangent) but I don't like the chimney effect and potential fouling.

I also bought a K-type thermocouple ($5) so this could be a pretty sweet forge if all goes well.

I wonder how long that 5 dollar thermocouple will last. I'd recommend looking into a more durable piece of gear. Along these lines, but 18-24 inches: Super OMEGACLAD® Thermocouple Probes - Quick Disconnect Probes with Miniature Size Connectors They can handle a forge or liquid atmosphere a lot better than a dangly wire bit. A good thermometer or digital multimeter would be helpful too.

I've not had problems with the tuyere burning out the soft wool liner even with the tangent setup. The forge really works more on the principle of radiant heat not direct flame impingement. Once the whole liner has warmed up and turns a nice glowing color, there really isn't any direct flame any longer. More like a hot plasma...

Awesome points. Keep in mind that my present arrangement is a chiminea with brake drum for charcoal, or my gas 'forge' consisting of four firebricks with hole in the side for the Bernzomatic 8000. Both are located in my tiny single garage along with the Grizzly, homemade grinder, work bench, 'massive' 50 lb anvil, family storage and car.

The $5 Amazon thermocouple may well be a novelty but it's leagues ahead of what I have now. And I need to keep some powder dry for my apparent case of HAD.

I'll try to make some progress in the coming week and then check back.

Some progress. I am a sh!tty welder.




Ran out of mig wire half-way through. My stick welding skills are worse, especially with old rods.

Still haven't cut the hole for the burner or thermocouple (need a piece of pipe).

I made a hole through the back of the forge in case of long stock, and made a door to go over it. I will use fire brick on the door and might get braided wood stove gasket if I need to. Pics later.