Mikey98118

Frosty, The search for the "perfect forge" is like the search for "truth"; it's not a destination, but a journey. I like this journey, just as you like pounding iron; may we both be happy with our lot, and may others benefit from more choices. I get the occasional thrill from a new "Formula One bit of equipment every now and then. After fifteen years in ornamental iron, artwork lost all romance for me, but learning and inventing is still a kick alter fifty

Why use exterior baffle plates or walls of brick, instead of partially enclosing the forge front and back openings? There isn't any such thing as an optimum hole size from an exhaust vent. Too large and you waste energy; too small and you apply back pressure against the burner. If you figured out some mathematical formula to come up with the right vent size for a given burner, you'd still be out of luck, because most burners have a turn long down range. If the burner and vent hole match at one setting the hole is either too large or too small at every other setting. Fortunately, there isn't any need to make an exhaust vent; just use a variable distance baffle plate made from a high alumina kiln shelf (or stack of bricks) instead, and you can adjust your forge exhaust opening to perfectly match any burner size or setting. an exterior baffle also permits recovery of radiant heat that would otherwise be lost, reduction in noise (as sound waves don't turn corners very well), and hot exhaust gases are directed up and away from the smith. You might ask "if this system is so perfect why isn't everybody using it already?" I would answer "for the simple reason that most people feel that good enough is good enough; and they are right...so far is that goes. On the other hand, when you are building a forge from scratch this isn't more work; it's just a different design path.

One othher specific: You want to buy a 3 pound coffee can that has a peel off plastic seal on its top side, beause, under that plastic seal is a 1/2" wide rim, which will stiffen up the can quite a bit.

Loved the photos of the hinge; they really were worth a thousand words.

Mister Tim, You need something to reflect IR back into the forge and slow down hot gas exhaust a bit; even just brick in front of the openings.

Nate, You want to aim the burner at a hard refractory surface, whether castable refractory, a hard refractory brick, or a high alumina kiln shelf, or at minimum a mortar coating. Any decent burner wil; quickly destroy ceramic fiber, if you allow direct flame impingement on it.

They are totally right about needing a regulator, but you could also have gotten some very unpredictable back pressure effects from possible steam formation, which will continue until all water is boiled out of the rigidized ceramic fiber.

Of course, you could just use the washer for a choke and simplify everything...duh

Once you build or buy a burner, you'll want to install it in a forge or furnace, which brings us to burner ports. Some people just drill a hole in the steel shell and form a matching hole in the refractory, but this doesn't provide support for the burner or any way to fine tune its aim within the equipment, so others attach a short length of pipe or heavy wall tube, and use six thumb screws, in two rows of three screws each, to trap and aim the burner. So much for the obvious. Now let's discuss control of secondary air, and cooling of the burner. Even single combustion wave burners can benefit from external cooling air, if the burners penetrate extra thick refractory and insulating layers (more than 2") or are vary small 1/4" or less, because internal cooling from the cold incoming propane could be overcome during very long heats, under these conditions. Most burners have at least primary and secondary flame envelopes, so some builders deliberately leave their burner ports unsealed during operation, because secondary air induction (now powered by the flame) is needed for complete combustion. Unfortunately, this nearly always leads to an overabundance of a good thing, because the flame becomes an even more powerful induction "motor" than a burner's gas jet makes. It takes energy to heat air, so extra secondary air becomes a drag on performance within the equipment; typically a 20% heat reduction. Fortunately, we don't have an if/or choice to make. It is just as easy to control incoming air through the burner port as incoming air through the burner. First, add another choke at the end of the burner port's tube; mount a washer brazed to a ring with thumb screw on the burner; once the burner is installed, it can be slid up against the portal tube's end to seal the port when needed, and moved away from the opening to varied distances, as desired to control secondary air flow. Is this more work? Obviously; should you expend the additional effort? Also obviously. But what about single combustion wave burners? Better to have a way to cool down the burner when needed, than to depend on luck. If your burner suddenly starts back firing you won't care about temporarily losing some furnace efficiency, so use the same burner port changes for them too. Also if a Mikey burner isn't perfectly made, and perfectly tuned, you will need a very little bit of secondary air for complete combustion in a forge or casting furnace; better to have it than risk even trace amounts of carbon monoxide in your shop.

So, what can we do to tweak burner performance from a shorter tip? Try taking the gas pipe down to your local hardware store, and finding plastic tube that can be inserted in it, to improve laminar flow between pipe and gas jet, in order to get the same effect that Larry Zoeller did by switching from schedule #40 (about 14" I.D.) to schedule #80 (about 3/16" I.D.)1/8" pipe.

How much gas depends on what size the forge is, and how well it's built.

Doesn't really matter; it's still a good subject for the rest of us

"What's best is unimportant you really want something that works well, leave best for folk who like to eek the most possible from devices. Once they've sweated their hair off we can thank them and use their designs. Thank you Mikey. Your welcome Frosty; so that's why my hair is thinning!

"Wash the blanket with rigidizer and kiln wash AFTER you drill the burner ports or it can turn into a real mess." Nice point there, Frosty. Frosty, I recommend up to 1/4" of refractory, mortar, etc. as a hard coating (AKA hot-face) over rigidized ceramic fiber, and also plan to try using you "kiln wash" idea before doing it my preferred way on the next forge.

Their prices are right. After buying all those burner parts here, you might save twenty bucks doing all the construction work yourself. Svings on the forges would be a little bit higher on their forges.

Light Hammer, In the first place, that isn't a half bad flame for a burner running out in the open air. I would suggest replacing the tapered flame nozzle with a straight nozzle one size larger with a spacer between it and the mixing tube, but first, try moving your tapered nozzle back and forth on the mixing tube to see if performance changes for the better.

Hybrid pipe/refractory flame nozzles: You can build a flame nozzle that is a compromise between S.S. nozzles and refractory blocks. Using oversize thick tube or schedule #40 mild steel pipe to provide enough material to securely mount set screws in;. You can save a lot of money on materials cost when building nozzles for larger burners this way. You also gain the ability to use propylene and/or oxygen enrichment to increase flame temperatures far higher than any mere metallic nozzle could withstand. The refractory interior helps keep the metal shell from collapsing at top heat, while the shell holds the refractory nozzle on your burner, so that more than one nozzle diameter can be employed, while refractory wear and tear is easily repaired, or the hot-face replaced; unlike the case with refractory burner blocks. High heat castable refractories can be used as the hot-face layer, while ceramic fiber blanket can be placed between the hot-face and stainless steel shell; this blanket helps insulate the shell from the superheated refractory hot-face inner layer. The springy blanket also helps seal the nozzle, so that six screws can continue to be used to hold the nozzle assembly centered and parallel on the burner, rather than constructing a work intensive fitting on the nozzle’s rear. what makes this nozzle workable for direct exposure to the flame is additives like Rigidizer, and high heat mortars like Sairset, which can act as a hot-face surface and are easily repaired from flame damage.

Rigidizer is nothing more than fumed silica, which is a colloidal substance, witch means that it stays suspended in water, unless it's allowed to freeze. A little ordinary food coloring is added to enable you to see how far it has penetrated into the ceramic fiber layers. Purchased from a pottery supply, it's expensive, and costs a lot to ship, since it comes already mixed into water. Purchased online it is cheap and sells for a song, because it is feather light; buy fumed silica, a plastic jug, and swipe some of the wife's food coloring; mix up you own Rigidizer, and save a pile of money. Perlite also costs very little, when bought by the bagful from the garden department of large hardware stores

Existing tin cans make nice cheap furnace shells, with built in bottoms, which makes them pretty irresistible for first time builders of portable forges and furnaces. When someone mentions making a shell from light sheet metal and pop riveting it together for more convenient diameters, most of us just shrug off the suggestion. But recently I stumbled across double wall chimney inserts that are filled with...you guessed it; ceramic fiber. Naturally they are too expensive to be very tempting, but they got me to thinking... Two different diameters of sheet metal pop riveted together could be filled with Perlite that is glued together with Rigidizer, making a highly insulating and quite rigid furnace shell for a minor monetary output. And since such cylinders can be made into larger diameters than the usual shell sources, they could also contain an extra layer of insulation and still have plenty of room left inside for hot-face and insulation layers. Of course the builder doesn't need to use a tubular shape; this kind of shell would also lend itself nicely to oval body forges...light sheet metal can easily be cut tp any desired shape for front and rear faces. By making the outline and then a larger outline 1/2" beyond and parallel to it room can be left to cut in tab shapes with a rotary tool, which can then be bent 90 degrees, and later drilled, with the part in place, holes can be drilled through end piece and outer shell wall beneath; they can be pop riveted in place, making the shell quite a rigid form to add the insulation into; afterward this form is little heavier than a simple tin can, but much tougher. Burner ports can be attached to the finished form by employing a hole saw, to drill through both walls at the desired angle, forming four drilled tabs on one end of the tube, shoving the tube through the holes from inside the shell, drilling matching holes through it, and employing pop rivets or sheet metal screws to hold them in place. With the tubes penetrating two separated sheet metal walls, the burners will also be held rigidly in position.

It is only mentioned in the updated version due out next year, but I've modified my original advise about employing 4-1/2" angle grinders for all the work, to include hand held rotary tools for cutting out the air openings. In 2004 these tools and their accessories were just too expensive for most of the starving artists the book was dedicated to; today this isn't true. If you feel that both tools are too great an expense, choose the rotary tool over the angle grinder. Also Dremel's 1-1/2" spring loaded EZ mandrel, unlike much of their overpriced stuff, is worth every penny on this kind of work.

Frosty, Your advice about cleaning the cylinder is good; I should have been more specific in my description, because I assumed the very same thing; what an eye opener it was to find that some (not all) old cylinders where pretty clean, while some (not all) fairly new cylinders were filthy. The worst mess I ever saw was at the bottom of a Blue Rhino cylinder...how did this come to pass? because of the D.O.T. requirement for amti-overflow valves to be installed in propane cylinders, there were fairly recent examples available, and my propane dealer was more than happy to give me all the reject cylinders I wanted. That should read "anti."

You are right, Charles: Unfortunately, it doesn't take people long to figure out how inefficient that positioning is, and they are inevitably tempted to push the torch tip part way into the hole. A workable compromise would be to add a burner holding exterior pipe with a rotating choke, so that secondary air can be controlled; best of both worlds, but don't hold your breath waiting for people to do it

Frosty, Good alternative. I know these jets are standard parts, but not where to look for them; it would be nice to have that information. since I'm seeing them on more air-fuel torches all the time; any clue?

Finally, Luer-lock needles are superior to MIG tips in smaller burners (3/8" and under) because they are too thin fo enterfere with laminar air flow past them. JPTV, A lot more research has been done since that book was published: you have perfect access to its author, but I can't answer questions that you don't ask.

For the people who don't believe they can find the recommended MIG tip: You can also employ a Luer-lock dispenser needle, with the recommended orifice size, on a Luer-lock adapter (AKA a plug; this is the needle to connection fitting you need); they come in both nickle plated brass (economical) and stainless steel ($$$). McMaster Carr carries them, as does Vita Needle, and other online sources. The adapters come in various popular thread sizes, including 1/8" male pipe thread. By swhitching out the 1/4-28 tap for a 1/8" pipe thread tap, you can run the needed thread directly into standard schedule #40 1/8" pipe that is available at your local hardware store. Look up the actual orifice diameter of the recommended MIG tip; not its call-out size, which is listed for the welding wire diameter each tip is supposed to run. Warning: Do not use Luer-lock needles or adapters with plastic bases; they might melt, and turn your forge into a flamethrower! An .023" MIG contact tip feeds that size wire in a MIG gun, but its actual orifice size (AKA inside diameter) is .031"; this isn't the optimal orifice for a burner made with 1/2" schedule #40 pipe; just the smallest size MIG tip available. The optimal orifice is .028". Needles are usually listed by gauge size, which is nearly useless to you, because gauge size has to do with their outside diameters, but needles come in heavy, medium, and thin wall versions. So, look for the inside diameter before buying. Where two different MIG tip sizes are listed in the book, this means that one is a touch too small, and the other a touch too large. Look up the actual orifice size for them on page 22, split the difference, and look for that inside diameter, or as close as you can get to it, in your dispenser needle. Those of you who did find the right size and length MIG tips, can also use the optimal orifice size by inserting a dispenser needle into a MIG tip with close to the right size hole to match the needle's outside diameter, by bending a curve into the needle, and then cutting off the protruding portion of needle; next, use very fine sandpaper, a bit of spit, and a circular motion to remove any internal burr from grinding the needle apart; torch tip cleaners will also work for this job, but are more difficult to employ.