Another keg furnace

Discussion in 'Furnaces and their construction' started by joe yard, Feb 16, 2018.

  1. joe yard

    joe yard Silver

    I am new to the form but have been learning quite a bit reading the post.
    I am not new to foundry work entirely. I have had a bit of green sand experience.
    I need a furnace that can cast bronze. I have accumulated the items in the condition pictured. The keg is very nicely cut. There are 3 rather unprofessional tabs for ? buck riveted to the top, 120 degrees from each other.
    If the liner is centered in the keg it gives an annular spacing of 3 inch and an average of 3 inch on the top and bottom. At this time a picture is worth a thousand words. I have run some test on refractory that I will post later.
    The fuel plan at this time is a 3/4 inch residential NG line and I will be using a petroleum based fuel secondary also.
    So this is where I am and I would like ANY advice and or questions on how to proceed. I do not like to look back and question if I should have looked forward and questioned. foundry keg with liner.JPG foundry keg.JPG foundry liner.JPG
    Mark's castings likes this.
  2. Petee716

    Petee716 Silver Banner Member

    Welcome to the forum. So what does that give you for a bore diameter? It looks like someone went to a fair amount of trouble to make the bore components. Any idea what they're made of? It's nice that the keg is already squarely cut. I didn't find it terrible difficult to cut mine, but it was unpleasent. I cut the inner part of the lid out of mine and poured refractory in, backed by kaowool. The groove in the lid acts as a support for the refractory. My build is over at Alloy Avenue

    The keg is a great vessel for a furnace but working with the stainless (cutting, drilling holes, welding) was kind of a pain in the ass. I'd personally probably use something else next time, but the lack of rustiness is kinda nice.

  3. Jason

    Jason Silver Banner Member

    I have a love/hate relationship with stainless steel. I'm all for new ideas, but this 3/4" household pressure NG I wanna see! I hope you can pull it off... CAREFULLY
    I love NG because it's dirt cheap and light and go convenient, but when I fart with more PSI than what NG is delivered at, it can present problems getting it working right. Unless you already have a plan in place for your burner, you might want to visit my NG ribbon burner. THAT is the burner my next furnace will have no doubt about it. See it here, Remember a forge is just a furnace laying on it's side. Read over that and lets see what your thoughts are.

    Where you in the world Joe?
  4. joe yard

    joe yard Silver

    I came by the lining some years ago when I became the owner of a small shop in Lincoln In. I later bought the keg. It became available just a couple days ago. I had planed to put the lining and refractory in a large can of roughly the same size as the keg. I had one on hand at the shop. Luckily I ran into this keg at a very good price. I am still very much in the learning and planing stage. Being lucky enough to have found both lots of parts worked out quite nicely. The fit is ‘GOOD’ in the burn chamber 9 inch wide 13 inch tall, 3 inches of side walls in all directions. There are 2 things that concern me, the lining and the burner hole. At this time. It has a cut out at the top 2 inches deep 4 inches wide the burner hole begins 3. 5 inches from the bottom has a diameter of 4.5 inches then 5.5 inches to the top, the 2X4 inch cut out is centered over the burner. The burner hole has no taper, the bore is straight. The vent at the top has given me some thought to as how I might want to vent the lid for a lost heat reclaim setup.
    On the gas. I have no idea but thought that the gas was there to was as a preheater for the petroleum based fuels. If it will work predictable and consistently, producing a number 10 crucible of bronze in a reasonable amount of time. Using natural gas would be the most convenient. If it will not work properly. Then it will be propane. At this time I do no see a need for cast iron melt. I am wanting something that I can make controlled melts of a known alloy in bronze. It is for a bucket project that dun right, with luck. This will see the sun by spring. It will be tested outside but could easily end up inside before the fall. It is with the highest of hopes of my grand son, the skill and willingness of my son too help, and me! We will melt a little metal this year and have a lot of fun. It does not have to be fancy just efficient, safe and well designed.
  5. PatJ

    PatJ Silver Banner Member

    A Morgan Salamander-Super (the clay-graphite crucible I often use) measures 6.3" top outside diameter, 4.3" bottom outside diameter, and 7.9" tall.

    The crucible will sit on top of a plinth that may be 2"-3" above the floor of the furnace, with the centerline of the burner tube aligned with the top of the plinth.

    You should haven enough horizontal and vertical clearance with your inner chamber dimensions using a #10 crucible.

    There are several good keg furnace builds on the net.
    Mine is here:

    I started out by looking at a variety of furnace styles, and then combining/customizing what I thought were the best ideas from each of the various designs.

    If you don't want to use the upper hole in your lining, you could close it up with refractory.
    If you ever need to replace the lining, you can always use hard fire bricks stood up on end in a circular shape.
  6. Jason

    Jason Silver Banner Member

    NG can be used for preheat. But so can diesel. I am running a kwicky burner and in my recent #6 bronze pour, I did the entire melt (3 crucibles worth) completely on diesel. (jet-A, but close enough) Diesel doesn't require preheat where motor oil or veggie oil will need a pretty hot furnace to start with. In my last melt, I forget to switch over to the used motor oil. It happens some times. Any blown venturi style burner should get plenty hot on just diesel to melt aluminum and bronze. Mine will. You don't have any desire to melt cast iron, so no biggie there. You've probably heard this before, but 1st thing to always buy is your crucible. You build the furnace around that. For diesel/oil burners, allow a good 2" clearance all the way around the crucible. For propane only furnaces, only enough space for the lifting tool is necessary. I see many furnaces on YT that have way too much interior space and running propane. (bigstackd) This is what wastes energy and takes longer to melt a pot of metal. A keg is a big animal and most keg builds I see have too big a bore and are too tall to melt metal quickly without draining a propane tank. After you have your crucible, get cracking on your burner once you nail down a fuel source. If you have a compressor and not afraid to use it, I recommend going with a Kwicky, just my opinion. It's cheap and easy to build and doesnt require any special machining and the hardest part necessary is a little soldiering. Not too bad right? If you want easy, idiot proof and don't care about $$$ burning propane, there are a 1000 propane burner designs. Keep in mind, a blower helps big time and keeps melts happening quickly. I melt a full #6 crucible of bronze about 13lbs of metal in about 20mins. Not shabby and costs me zero in fuel because I burn sump jet fuel. By law it can't go back in an airplane, so I drain off the water and burn the free fuel.

    If you ONLY want to run a furnace on 100% NG, this will take some brain power. I've done all the hard work as you can see in that forge build at AA. This will require some welding and careful use of a castable refractory like Mizzou. Look around here, you'll find some great ideas on a refractory cement shell that is lowered inside a tank. The left over space can be filled with sand, clay or cat shit. These work really well and require less refractory but take more work building the necessary forms to create the shell. Speaking of Refractory cement. Do this right, do it ONCE and spend the money on the proper stuff. You didn't mention where you are located. Hopefully you are near a large US city where you can buy Mizzou or Kast-o-lite. Both are excellent materials that will last for years and years of trouble free melting. Going cheap on some home made refractory brew will only haunt you after the first melt. Hope some of this helps you out. If you haven't seen the tour of my setup, it's the first 10mins of part 4. Here is a link.
    Last edited: Feb 16, 2018
  7. joe yard

    joe yard Silver

    The furnace lining is factory molded light refractory brick. It has a sn. but no mfg. It was from the cold war days and most likely the property of the Haines- Stellite Co. They manufactured mostly tooling along with hard facing metals.
    Sadly today they are a shadow of what they once were.

    The video is the best on something close to the scale I want to build. I did not plan on melting the bronze with the natural gas alone but also injecting the oil when the chamber was glowing.
    I must say and admit I skimmed. I was very impressed with your burner set up. I will look further into it afer some sleep.
  8. Petee716

    Petee716 Silver Banner Member

    You still have some options on your construction but now is a good time to decide on whether you'll actually be melting with gas or not. Preheating with gas won't be an issue, but melting with gas will. If you melt with NG or propane you will need to back up your bore assembly with insulation. Whether you decide to use insulating refractory or ceramic fiber, you'll need something. Otherwise you'll waste a lot of fuel and hard earned $. If you're going to use waste oil it won't matter so much. Free oil burns hot, is free, and doesn't cost anything. My furnaces are all solid. I use diesel or propane to get hot, then switch to oil.
    It's hard to tell how well your prefabbed bore will perform. If it's just soft firebrick it will probably start to erode pretty quickly around the area of the target wall. Furnace bores take quite a bit of punishment from flame impingement and lifting-tool abrasion. The good news is that it can always be patched and repaired. There are protective coatings that can be applied as well such as ITC-200 and Satanite, but I don't know much about them other than what other folks have shared.
    Your cast-in air hole (tuyere (tweer)) won't need to be much more than 2.5 inches or so, so there's plenty of room to angle you're air tube form and just mud in the excess diameter with refractory. The "refractory" you see at local big boxes and fireplace shops isn't the same as what we're talking about. That stuff might be ok to mortar your sectional joints but it is not an adequate substitute for real refractories like what Harbison Walker and others offer. Kastolite-30 and mizzou are a couple of the more popular ones. I'm guessing your location in your profile is your zip code. If so that puts you between Indpls, Southbend, etc. There should be industrial suppliers nearby.

  9. joe yard

    joe yard Silver

    I do not intend to melt with the gas. It will be used just to pre heat waist oil. It should have adequate insulation as it will have the refractory lining 1 inch = 1 inches in all directions from the burn chamber of some kind of refractory.
    Short answers tonight but I was hit hard with the flue today and just had a tooth puled.
  10. DavidF

    DavidF Administrator Staff Member Banner Member

    Damn man, going to be a rough night for ya... We will keep the fire lit for your recovery :)
  11. joe yard

    joe yard Silver

    I am back, well sort of. I am on my feet again but not even looking at picking up anything heavier than a knife and fork. This flue this year is a nasty one.
    In my last post I stated that the liner will be 1 inch around the burn chamber. I wanted to say. The hot face liner is 1 inch thick and will be backed by 2 inches of some kind of insulation between it and the keg wall for a total of 3 inches. I know it is not realistic in a furnace of this size but I would like to have a side wall outside temperature of not over 150 F.
  12. Jason

    Jason Silver Banner Member

    You'll probably be over your self imposed limit of 150 with just 2 inches of insulation. The external temp of your shell is directly related to the thickness of your wallet.:(
    You are going to burn oil. A little bit of heat loss will be acceptable when your fuel is free. My setup is 1" mizzou backed up with almost 2" of kaowool. Melt times are fast and the outside of the furnace gets at least a couple hundred degrees. This is pretty much the norm and works well.

    I had a short round with the flu a couple of weeks ago.. The joint pain was unbelievable and the rapid hot/cold swings were the worst I've ever seen.
    Drink your OJ, climb on the couch and look through this. Hobbyist's Guide to Casting Metal--2nd Edition (print).pdf
    Rtsquirrel likes this.
  13. joe yard

    joe yard Silver

    As the days pass I am feeling much better!. I was outside the house for a couple of hours today. I suspect that early next week I will be creeping back on the project. Petee has suggested a 2 ½ inch tuyere hole. I will take his advice on that.
    Before I put the lid in the lathe to cut the vent hole. What would be the suggested size of this hole?
    My health and endurance are both sub par so progress will be slow.
  14. Jason

    Jason Silver Banner Member

    2 1/2" tuyere is a good size. you can always neck it down if you need to. Exhaust holes should be minimum 3inches.. 4 is better. Oil burners like large holes and propane can be a little smaller. Again, you can always neck it down with a refractory ring. I would do 4. :)
  15. Petee716

    Petee716 Silver Banner Member

    Forming the lining for the lid will take some thought. As I mentioned above, I cut the inner dome of the lid out and formed refractory in it. A link to my build is in post #2.
    Fishbonz didn't cut his out, he used just kaowool suspended from above and coated with satanite. Both methods work.

    I agree with Jason on the 4" exhaust. Not only for good combustion but so you can lower material into the hot furnace without opening the lid.
  16. joe yard

    joe yard Silver

    Thanks to every one on the forum! I think I am conceiving a better idea of what I would like on this one. Petr I watched you’re video but I missed the lid construction. It is said that to copy some ones design is to flatter them. When this furnace is finished. I it will be more a compliment to those of you who have helped design it than the builder. This will be at a snails pace so finalizing parts of the design will be put of until the time for that particular part. For now 2 ½ inch tuyere hole 4 inch vent, cut and raise the dome 2 inches. My location is Logansport In. 46947 My user name is my real name and also my email address. Just add @
  17. joe yard

    joe yard Silver

    I did make it out to the shop today. Although it is not a lot of progress under the circumstances I am very happy. I was a bit surprised at how non concentric a bear keg really is. I cut the dome out in such a way that there is a small lip left around the original keg to help retain the refractory placement. This now gives me an extra 2 inches of room above the crucible. Due to the inside diameter of the burn chamber. I would think it best to use this space for insulation and refractory rather than chamber space but I would like the opinion of those with more knowledge on the subject than myself. The refractory material and supplier is still undetermined at this time. I have several months before that becomes a major concern. The burner will be in the planning soon and I have been looking at some options along with the advice given. I do have an ample compressed air supply along with a few selections for blowers from small to large commercial models. I might be off base but I did find a small positive displacement gear pump that I might be able to use as a metering pump to help regulate fuel flow, when the time comes.
    I am not one to rush a project like this. I learned as a young man that I am quit capable of fixing many things ignorance being one of them. There will be many things to build buy or scrounge before this project is finished. The furnace is only a very small part of the process.
    Joe foundry keg lid.jpg
  18. joe yard

    joe yard Silver

    I have made some however minimal progress.
    I drilled a pattern of 8 sets of “ 2 each, 1/4 inch holes spaced ½ inch apart” evenly around the rim just under the handles on the lid. I then did a basket weave with 1/16 stainless tig rod around the perimeter leaving an approximate 8 inch octagon hole in the middle of the woven pattern. I have also cut the tuyere hole.
    I plan on welding the dome on the very top soon.
    The more I look at this project and study on it. The less forward it becomes. I have came to the conclusion that the tuyere hole on the lining is in to high a position for this application so I have decided to plug the original tuyere hole in the liner with refractory and reshape the rectangular cut out on the end to be used for the new tuyere.
    The other thing is the more I look at how the lid will be on a pivot lift. If I might not want to cut the bottom of the keg out and also have a provision for lifting the side wall? I would then have a top that pivoted to a side, attached to a side wall “tube” that lifted 24-32 inches and a stationary bottom attached to the frame.
    This would eliminate the need of lifting tongs and allow me to pick the crucible up directly with the crucible pouring assembly.
    Please let me know what you think!

  19. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    As someone who owns and uses a lift off (body) furnace, though I like it and am very happy with it, it is a significant complication to a furnace build and expense. I had many reasons for adopting that approach but building and using tongs is much simpler than a lift off bronze duty service furnace. IMO at that service temp and up you need a hot face and that makes the body and lid heavy. You still need a lid to access and recharge the melt.

    You might try searching Raku Kiln, or top hat furnace, top hat kiln. They are typically a light weight wire cage with refractory wool attached and in many instances you could lift the body with one hand. I don't think they would be durable enough for bronze use but fine for aluminum.

  20. joe yard

    joe yard Silver

    Thank you for the quick reply Kelly.

    At this time I am still in the design and parts accumulation stage more than the build stage although that is changing. Early building has started. I want to weigh all of my options. I am more concerned with safety and ease of use after the build. Rather than the time or complexity of the build. Any design to lift the shell and top will have a hoist incorporated. The thought a furnace that lifted straight up might prove safer and easier to use in that I will not have to lift the crucible with lifting tongs. I have no experience with this type of set up. I would like your opinion along with others. Is it is superior? If so what the prose and cons?

    I know most start with the furnace and build from that. With my material resources piled in sheds along with unknown storage boxes and bins. The final configuration will be strongly influenced by what I can sort or find in the coming months.

    A minimal introduction might help. I have been in poor health limiting my shop time and endurance for several years. Any strenuous activity is kept at a very minimum. This is not to say I don’t get things accomplished. They just take a lot longer and are more thought out to avoid lost labor. I have a 35 year old son whole is very talented and willing to help along with an 11 year old grand son who loves all shop related projects.

    The shop is in a bit of disrepair due to recent events but well suited for most metal projects with 75% of the building being climate controlled. The remaining 25% is metal pole barn style with a cement floor. This is the hot room and will be were the foundry will eventually be. Equipment on hand, lathes, mill, torches, grinders, press, welders and most of the things we dream of when we are young. All of it is old! The larger lath and the mill are large enough to chuck up a bear keg. Coupled with 40 years of some mighty fine junk yard scrounging. We have a lot of odds without ends. The resources are there. Unfortunately I am not the man I once was.

    The budget. THIN!

    If the General opinion is that one type is superior to the other. That is most likely the type I will build.

    I find myself now wanting to add a small foundry. I do have a bucket list project that will require a foundry. This makes for the opportune time. I have no real schedule for this project although I would like things up and running smoothly by late August or early September.

    As always any suggestion or advice is greatly welcomed!


Share This Page