prburner

If you go with the threaded rod clamping method, put an old automotive valve spring between the clamping bar and each tightening nut on the threaded rod. As the bricks expand, the springs compress. As they cool the springs keep the roof tight. This is how we made flat roofs for pottery kilns back in the day. Lasted longer than any other method we tried.

Hello kraythe, The thump and low rumble sound you hear means the burner is backburning. All combustion should take place from the face of the burner outward. But when the combustion rate of the fuel mix is greater than the outflow speed of the burner, the fuel mix then burns down inside the burner orifices. If you look at the last picture in your post you can see that the orifices are still glowing red inside, a sure sign that combustion was taking place inside the burner. Backburning will greatly reduce the life of the burner. You are right about rethinking your choice of castable. Kast-o-lite 30 is an insulating castable. It does not have good mechanical strength ("some minor breaking around one jet" after 20 minutes use is a clue). Much better to use a hard refractory castable. Choose one rated for at least 3000 degrees and designed for repeated heating/cooling cycles. Regards, Tom

I would not recommend a flat roof. Go with an arched roof. If it is supported on the edges, even if it cracks it won't fall in. I would also go thicker than 1". 1 1/2" minimum There are photos of how I build forms for Kastolite 30 roofs on Facebook. http://www.facebook....77315?sk=photos Look at photos of "small forge 1" Tom

Here is another take on the variable size forge. Mount the burner to a table base and stack up the bricks any way you want. Burner and plumbing stays put. You can use pottery kiln shelves for a roof on larger forges. Tom

ToolSteel, email me at sales(at)prburner.com Tom

These guys are about 15 miles away in Veneta. http://www.nwironworks.com Look under refractory supplies. The brand they carry is called Cerablanket. Ask for Vince. Regards, Tom

Hello ToolSteel, Sorry about the late response, just got back from vacation. I don't have written instructions, but do have lots more photos. If you (or anyone else here) decide you want to try and build a forge like this one, I could email more detailed photos. Regards, Tom

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I, like monstermetal, have also fooled around with a top mounted ribbon burner on an adjustable size forge. I was never happy with the results. Too complicated and not as versitle as I would have liked. Have been happy with my "brick pile" forge with a side mounted burner. The burner is fixed at one end of a table made from a castable refractory material. I stack up loose bricks for walls and use kiln shelves (covered with fiber blanket) for a roof. Easy to adjust size and heats up quick. Table size 27" x 22". Pine Ridge LP190 burner.

Charlotte, I too have some issues with the Hammer's Blow type design. My main concern is the way the cast block is attached to the steel shell. Cast refractories shrink some when fired, and if fired hotter on one side than the other, they are also prone to cracking. With the burner block attached directly to the plenum, a crack in the burner block or leak at the block/shell interface could allow combustables to migrate into areas of the forge other than the combustion chamber. Since this part of the burner is buried in the forge wall, there is no way to visually inspect it. I like Brad's design because a hard firebrick is evenly pre-fired so there will be no further shrinkage, and it is much less prone to cracking. As long as there is no warping of the steel shell, a good quality high temperature mortar should provide an adequate seal. I use a steel plate to isolate the plenum from the burner block. The only way combustibles can leave the plenum is through the metering tubes. See cutaway model of burner below. Brad, What type of drill bit do you use? Any problems with cracking the brick when drilling that many holes in it? Tricks or tips? Regards, Tom

Brad, Nice job on the burner! You have put a lot of thought into it. In the past I have built several IFB (Insulating Fire Brick) burners. Even the G28's don't have the lifespan of a burner block cast from a high quality refractory, but since your design makes it so easy to replace that becomes much less of a factor. A tapered hole won't have much effect. What will help with flame retention and stability is a stepped diameter orifice like I use. The first part of the orifice is smaller in diameter. This is the metering orifice and it supplies a consistant amount of fuel mix at a relatively high speed. The second larger diameter part is the delivery orifice. Here the fuel mix expands and slows down just before leaves the burner. This helps the flame retain on the block face, and gives better flame stability over a wider turn up/turn down ratio. The trick, of course, is in balancing the relationship between both the lengths and the diameters of the two orifices. Whether or not you could get it done in the thickness of an IFB I'm not sure, but bit might be worth fooling with. Charlotte, "a little leak might not make any real difference" unless it leaks out into and behind the fiber blanket forge wall. Being a manufacturer I tend to see design in terms of liability. You will have to forgive me, it comes with the territory :grin: Regards, Tom

Brad, I'm guessing that the nozzel is an insulating fire brick (IFB) with holes drilled in it ? How do you seal it to the steel shell to prevent leakage? Are you still using the expanded metal baffle? Regards, Tom

Frosty, I can't agree with your idea of having the outflow of the burner exceed the supply pipe. It takes a certain amount of backpressure to evenly pressurize the plenum to the point that all the delivery orifices will burn evenly. This required backpressure is also the reason that a naturally aspirated system will not give satisfactory results. The keys to an efficient ribbon burner are an evenly pressurized plenum and accurate metering of the fuel/air mix into the delivery orifices. If you study the flame characteristics of most homemade burners and compare them to the photo on my site you will see what I mean. Charlotte, I had never seen a chip forge in action until the CBA Conference last month. I think a ribbon burner would work well for that application and have been rolling some ideas around in my head. I agree, side draft will be the first thing I will try. Someone bought a burner from me at the Conference to use in building a chip forge. He said he would keep me informed as to his progress. I will pass any info along. Brad, Using the expanded metal as a diffuser is ingenious. Looking forward to seeing your new version. Regards, Tom

Thanks for the welcome Frosty. Actually, I met James Johnson (Anyang USA) at the CBA Conference a few weeks back. He sugested I join your group. Figured I'd lurk until a ribbon burner question came up - didn' take long. To answer some of your original questions about "rules of thumb" : As you figured, the number of and placement of orifice holes is important. Too few holes and the burner block will not keep itself cool and you will have backburning problems at high temperatures. Too many holes and the structure of the block will be weakened. Either way you will have a short burner life. I use a 13 to 1 ratio. That is, the area of the burner face that is solid is 13 times the area that is orifice. Example : one 5/16" orifice for every 1 square inch of burner face. As to placement of the blower output in the plenum. This, of course, becomes more important as plenum size increases. The pipe you see entering the plenum on my burners runs the entire length of the box. It is perforated in such a way as to distribute the fuel/air mix along the length of the burner, evenly pressurize the plenum, and at the same time create a vortex inside the plenum to further mix the fuel and air. Even with a properly baffled delivery system, if your blower output is in the 1" to 3" WC pressure range you are limited to a maximum plenum size of around 180 cubic inches. So yes, your friend will need more than one burner. Charlotte, A properly designed and installed ribbon burner uses the flow of fuel and air to defend itself from the heat of the forge. All metal parts should remain cool to the touch even after hours of operation. Regards, Tom

More information here Pine Ridge Burners - Home Page Will be glad to answer questions. Regards, Tom