plane_crazzy Posted April 10, 2013 Share Posted April 10, 2013 I am about to embark on building my first gas forge and was hoping for a little input before I began cutting things I cant put back together. I know it is longer than most would recommend but I usually end up doing alot of long bends and twists so I think the extra length is warranted. I am going to encase the whole thing in 10ga sheet metal and bolt it together with angle iron so I can take it apart if needed. Reading through topics on here I have convinced myself that a central straight down burner is best but I was curious about exact placement. With it being this long I know I need two burners but their exact placement is still to be decided. Also I was wondering if anyone had tried running one similar to this on one burner for smaller items but used a piece of proper size brick to block the back half of the forge? I also have hard brick I am going to slide in angle iron on the ends for doors there. Any input is much appreciated. Edit: Apparently pictures are not loading properly. Here is a link to it on imgur http://i.imgur.com/2sOzhzo.jpg Quote Link to comment Share on other sites More sharing options...
SoCal Dave Posted April 10, 2013 Share Posted April 10, 2013 I have a three burner Mankel forge and it is 20 inches long. You might consider three burners and not just two for that length. I don't think two burners will have enough fire power for your planned 18 inch chamber. I have twisted 12 inches of 3/4 inch bar and think that 12 inches is about the limit for my forge. As you have indicated, you need to turn off the gas and block off the hole to the unused burners if using one burner. Mankel forges have a blower which definitely helps. I use a one burner NC forge for small items and leave the mankel for larger projects. You can see my 12 inch twist in Member's Projects under Table Legs. Each 12 section was done as separate heating. The entire leg is 36 inches, which started out at 37 inches before the twists. Good luck. Quote Link to comment Share on other sites More sharing options...
plane_crazzy Posted April 10, 2013 Author Share Posted April 10, 2013 What size burners would you go with if using three? Quote Link to comment Share on other sites More sharing options...
SoCal Dave Posted April 10, 2013 Share Posted April 10, 2013 Crazzy: I have not designed or made my own forge, but there are some burners that many people have used and recommend. Without the third burner, I think you will not have enough heat for you large forge chamber and will cause it to take forever to heat your material. I have been very pleased with my three burner when trying to heat long pieces. I didn't notice if you have a small hole in the rear of the chamber for a pass through in your design. I found it useful to be able to pass steel through the entire chamber and through an opening when heating an inner section. But, I would not undersize the burners because you are using three. If anything, you will heat up your chamber and the material faster. Quote Link to comment Share on other sites More sharing options...
plane_crazzy Posted April 11, 2013 Author Share Posted April 11, 2013 The entire end is open, but I will have hard brick on a track that I can slide them apart for a pass through or together to keep the heat in. I appreciate all your input Dave. Thank you Quote Link to comment Share on other sites More sharing options...
Dave Hammer Posted April 11, 2013 Share Posted April 11, 2013 From the looks of your design, you are going to use brick to make your forge. I assume you are using soft firebrick (IFB) for the sides and top. I would recommend you use soft firebrick for the ends also (the forge will heat up faster if you do). It appears you may be considering using thin hard brick for the floor. That is fine, but I also recommend using a layer of soft brick under the hard brick if you do. The hard brick will need to be heated pretty much all the way through (to forging temperature) before anything you lay on it will be heated to forging temperature. That heat will be conducted to the table below. I recommend using soft brick on a metal surface under the thin hard brick. If you are not going to be forge welding in this forge, I would recommend using the soft fire brick for the floor of the forge rather than the thin hard brick. If fact, you could find some hard brick that is only 1/2 inch thick to use as a small platter when you want to forge weld (I don't know where to tell you to buy this, but I know it is available). Since your burn chamber (as drawn) is less than 500 cubic inches, two 3/4 inch venturi burners should heat your forge just fine. I would put them about four inches from each end of the forge. I use what I call a free form forge when I need a large forge for my projects (normally, I use a small round forge). If you are curious, I have a video on YouTube, showing how I construct it. My Youtube channel is djhammerd. Just look for the "Free Form Forge" video. If you design your burner setup so you can shut off one burner, you can easily use 1/2 of your burn chamber for the active forge. Just cut (or file) a soft firebrick down enough so you can slide it in from one end. Even with a little space around it (enough to allow you to slide it in), it will work perfectly. Good luck with your project. Quote Link to comment Share on other sites More sharing options...
EtownAndrew Posted April 11, 2013 Share Posted April 11, 2013 It appears that your brick gas forge will be similar to mine. I use one 3/4" burner in it but could use two when doing longer work that I want all heated up at once. Often I am working several inches at a time so one burner in the middle works fine. I can heat up somewhat longer work like an 8" long knife. I block off one end and end up moving the piece back and forth some to get it all heated. An advantage of the loose stacked brick forge is that you can rearrange it to suit different projects. Another advantage of a propane forge in general is you can turn it on to do some quick work and then shut it off if you need to stop suddenly. The disadvantage is the size. As soon as you put a couple bends in a rod it may no longer fit. I started out with this propane forge and then later built a coal forge. I now use the coal forge more often since I don't have issues with fitting the work I am doing into the chamber. I initially bought a case of insulated fire brick that I used. They have gradually all broken. I keep using them until they get down to being in about four pieces that I can't get to stay in a brick shape. Hard fire brick is much more durable but takes longer to heat up. It's also about half the cost. I really really messed up some insulated fire brick by trying to do some forge welding. The borax sunk into the porous insulated fire brick and I couldn't clean them up. Certainly use hard fire bricks for the bottom bricks to take the abuse. I started making mud bricks as replacements that are shown in the picture. Also I got tired of getting on my hands and knees and built a high table to raise the brick forge and allow me to easily see into it. Quote Link to comment Share on other sites More sharing options...
plane_crazzy Posted April 12, 2013 Author Share Posted April 12, 2013 how much heat you have sink through to the table Andrew? I was looking at my design and the angle iron that will hold it all together. Should I be worried about using zinc threaded rod? It will be about 2-3 outside the sheet metal frame but I want to be sure I dont need stainless steel rod for it before I buy it. Quote Link to comment Share on other sites More sharing options...
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