Another keg furnace

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

  1. Jason

    Jason Silver Banner Member

    I would think at those dimensions, a #10 is the biggest that should go in that furnace. It all comes down to having the space for your lifting tools to extend around the crucible and grab it. I would always plan for an oil burner and if you end up on propane, it just costs you a bit more in fuel. At least you'll have the space for a larger crucible. Don't agonize too hard over this, we all would have done things a bit different if we rebuilt our furnaces. I wouldn't build a rig for a #20 and then only use a #6, that's silly. I built for a #10 and use a #6 most of the time.
    My bore is 11" across and my #10 measures 6 1/2 across the top.
    Here is what it looks like with the tool sitting in there. I have about 1.5" of clearance on the sides. (yes, I think my furnace is about 5inches too tall. Not bad for my first build I think)

  2. oldironfarmer

    oldironfarmer Silver Banner Member

    If you can draw it and take a picture of the drawing it might help.

    If it's a lift off furnace why does it need a drain? (I'm learning)
  3. joe yard

    joe yard Silver

    That thing looks like an industrial accident. I am happy to say that as predicted the last exercise equipment my wife last brought home has been exercised.
    How thick are the sides of your furnace?

    On the drain. It is because the burner will be in a channel that would be the low spot if a full crucible failed in the furnace. I plan on the pith covering the drain hole. This will be at the bottom of a sump. The thought is if the sump floods it will float the pith exposing the drain. With the cart there is room to put a ketch pan with some sand just in case.

    Sorry for the lack of drawings and or pictures. I misplaced the camera at the shop the other day.

  4. Jason

    Jason Silver Banner Member

    About 2" Joe. Kaowool has a tendency to compact down a bit when ya start ramming mizzou.
  5. joe yard

    joe yard Silver

    So things have been coming along slowly to say the least. The furnace is taking a back seat to all the summer repairs I have neglected.

    I originally made the burner mold forum out of plastic and wood but decided that it just was not quite what I wanted. I then built one out of P.V.C and an inner tube but had problems holding dimensional shape. My third try is made out of Styrofoam with a plaster shell and sealer. It is by far the best but at this time a bit rough. After second guessing I cut the height down by 1 inch. I still have to put on the side tube part for the burner but it is close to being ready to cast in refractory. It will only be 3/4 inch thick on the bottom witch will make for a very hot bottom. I might end up setting it on an inch of wool.
    The refractory

    The refractory I bought off of E-Pay
    Castable Refractory Cement, 45% Alumina Low Cement Castable, Accomon-45,12.5 LBS
    $39.99 rated at 2822 F has particals the size of small pees and will not be suted for hot face.

    Another minor slow down. After the Kaowool and refractory that about shoots this months hobby budget! I will order Satanist in a couple weeks if I can find it. I just hate to pay $45 for the refractory and $55 for shipping!
    For now I hope that the 13 Lb. Is enough to cast t the burn chamber.
    On the barrel, I plan on putting 1 inch of wool around the bricks. This will fill in the walls then pouring a ½ inch thick lip on each end to keep every thing centered and give a good surface for sealing the top and bottom to the barrel.
    I got a new drawing pad the other day for the grand kids so I can play with it for 2 days before I give it up. I do hope it helps explain.
    In the picture where after casting is, It is suppose to say burnt out after casting.

    Joe keg lid.jpg keg rim.jpg

    Attached Files:

    Last edited: Jun 25, 2018
  6. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Joe, still not sure I completely follow the furnace features and dimensions you are describing, but just a couple comments.

    I'm not familiar with that particular refractory but 12.5 lbs is not much and it would take double that to cast just a cylinder that is 8.5" ID, 3/4" wall, and 12" tall. That doesn't include the floor, flange, or any material for the lid. With any waste at all, most people will use a 50lb bag of dense castable.

    Most dense castable refractories are at least 140lbs/ft3. That's about .081lb/in3. If you calculate the volume of everything you intend to cast in cubic inches and multiply by .081 that will give the weight of refractory required. Most people figure they will nee 20-25% more to have a successful cast.

    Having larger particles in the castable is normal. They are there to reduce shrinkage and increase strength just like the aggregate in concrete. It will still cast fine if you use the correct amount of water. If you haven't used castable refractory before I strongly urge you to read up on it first and consider using vibration to cast it in place. It is very difficult to mix and work at the recommended water content. I'd also recommend you break it into batches and only mix and cast each piece to insure you have the maximum available working time.........don't want to see you have a refractory casting fail.

  7. joe yard

    joe yard Silver

    Thanks for the reply Kelly. You are absolutely right in that I do not have near enough refractory. In the beginning I had intended on just using the liner I had and patching the holes with the trimmings from cutting down the 14 inch liner.
    Now I find that I have decided to expand the liner I.D. to 10.5 inches after coating with Satanite.
    The filling of the spaces between the original liner to expand it took 4.24 Lb and although I probably would have enough to pour the top and bottom ring on the barrel of the liner to .5 inch. I have decided to just use what is left to pour around the disk of light refractory I already have for the lid. Filling in the space between the light refractory and the edge should pour out at around 1 inch and be fairly durable.
    I will have to order more refractory for the bottom portion around the burn chamber and rim around the top and bottom of the barrel. What would you suggest I buy this time for refractory?
    The 2 pictures are of the sides of the liner “barrel” and the lid. The barrel is mostly finished other than the planed rims to be poured on each end filing in the gap between the liner and keg along with a 1 inch wrap of wool. The final dimensions of this assembly “barrel” will be approx. 13 inch tall 10.5 I.D. fit to fill keg width.
    The burn chamber.
    The bottom with the burn chamber cast around the Styrofoam bowl will be 4.5 IMG_2387.JPG IMG_2388.JPG inch deep with the hollow chamber taking up 3.6 inch of that depth leaving room for .9 inch of refractory underneath. The bottom with of the burn chamber cast around the styrofoam bowl diameter is 10 inches the top is 10.5. The widest part of the chamber is 12 inches around the middle.
    As you can tell I am not very skilled at explaining a 3 dimensional object, nor am I very skilled with a camera / video or paint programs. That’s pretty bad for someone who made a living in maintenance and electronics repair.
    Can you pleas explain what part I am not explaining well and I will try to do better. I know it is a bit confusing. The project is modified often and sometimes without clarification.
    Again thanks!
  8. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    What's always the killer when buying refractory is shipping cost.

    Looks to me like you are close to Indianapolis. I guarantee there is someone that has and/or sells castable refractory in's just finding them. I came up with a few hits searching "Indianapolis Refractory Suppliers". Businesses that service/reline industrial furnaces are also good candidates. I would contact them and tell them you'd like to purchase a 55# bag of the highest service temperature dense castable refractory and see what they have. I suggest this because I could throw out a bunch of different brands/types of castable, but if they don't use that type you're SOL. Many people find that those businesses sweep more castable up off the floor after a job than you want and often have open half bags that they just give to people that stop in asking. Put a post here and over at AA asking if anyone has a castable refractory source in Indy.

    I use Castmax 28 (2800F continuous duty dense castable) because that's what my local supplier uses and always has on hand and it's $35 for 55lb bag and on my way home from work. Suits me fine. A lot of people want 3000F and up refractory but most will never need it. If you had a high power oil burner and were routinely melting/casting iron, might be a different story.

    Think I'm beginning to see what you're up to with you last couple phoots and looks like you a re pretty well into the build. Keep posting pictures and I'll hum along.

  9. joe yard

    joe yard Silver

    Thanks again Kelly!
    I an about 70 miles from Indianapolis but I seldom make it out of town other than to go to the shop. I have had several seizures in the last few years, nothing life threatening and usually with a couple of seconds notice but they do cause total loss of conscious. So for the safety of others I do not drive except in an emergency and then only as far as required to get help or another driver. I will pay the $55 shipping if I must but I will complain about it!
    I was glad you gave me the advice on looking up the curing of the refractory. I had seen several forum post on the slow razing of the temperature after the initial drying time but had forgot about keeping things at a very high humidity for the first couple days. I wrapped the barrel in wool tonight and placed it under a trash can with a bowl of water that will be in the partial sun for this time. It looks like it will be a couple of weeks before I can get the new refractory. This should give me some time to work on the cart and other parts of the furnace.
    I finished the final shape of the burn chamber. I was lucky to find a plastic cup that i partially filed with plaster and attached to the doughnut. It is 2.7 tapering up to 3.2 inches. A 2 inch water pipe is just under 2.4 inches so there will be plenty of clearance.
    One last question for the night. Where would be the best place to put the thermal couple? I am thinking through the side and ½ way through the refractory brick? Would this be advisable?
    I will post a couple of pictures of tonight efforts. Again thanks to all that have helped along the way!

    Attached Files:

  10. oldironfarmer

    oldironfarmer Silver Banner Member

    Looks like your thermocouple has a stainless steel shield. In commercial furnaces those protrude through the hot face and measure the air temperature inside the furnace. If you og part way through the brick you are only measuring the temperature at that point which will be cooler than inside.
  11. Jason

    Jason Silver Banner Member

    Why measure that temperature at all? My furnace has one temperature. FRIGGEN WAY HOT. Not like this number will do you any good anyways. A kiln...okay... I measure that so I know when my shells are up to temp.
  12. joe yard

    joe yard Silver

    It is a K type so it could not take the internal chamber temperature. I just want it to adjust , somewhat monitor the burner efficiency by taking a wall temperature. The furnace will be on a role around cart, temperature monitoring is dirt cheep and I have a lot of room out of the way behind the heat shield. I just think for under $10 it could not hurt.
  13. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    In my PiD controlled electric, the TC is very useful if not essential because I use it for many things that require temperature control. It would probably be difficult to make a K type live very long if continuously exposed to a fuel fired furnace interior. I am still on the original TC after many hours of use but it is a high temp Inconel sheathed version installed in the furnace lid but even so I'm only running the furnace at 1800-1900F. The junction/interface with the TC wire is usually limited to lower temps.

    Installed within the wall of a fuel fired furnace it will probably only be useful to tell you where you're at in the warm up cycle which may be useful too but I suspect with use and experience, elapsed time may be just as instructive. I think in the long run you'd be happier building yourself a contact that is very useful tool for a home foundryman.

  14. joe yard

    joe yard Silver

    I was wondering if any one has used this refractory? SAIRBOND - 55 LB. BAG Refractory Mortar from HarbisonWalker International?

    SAIRBOND - 55 LB. BAG Refractory Mortar
    Be the first to review this item
    Price: $88.50 & FREE Shipping
    New (1) from $88.50 & FREE shipping.
    Specifications for this item
    Part Number 50005
    Measurement System Inch
    Brand Name SAIRBOND

    I will be ordering a 55 Lb. Bag soon and was wondering if it could be used thin as in 1/4 - 3/8 over insulating fire brick as a hot face?
    I will be casting the thicker parts of the furnace with it. The burn chamber and a couple of faces none of this will be thinner than an inch but if it will work. I would like to also use it as a thin hot face.

  15. Petee716

    Petee716 Silver Banner Member

    Ive not used it, but if given the option i would use mortar as mortar. Especially at that price. H-W has other products that are probably better suited as hotface if theyre available to you. Although Satanite is also a mortar and is being used successfully by some of our members, it is a high alumina mortar as opposed to sairbond which is fireclay based.
  16. oldironfarmer

    oldironfarmer Silver Banner Member

    It will work for a hot face and thin sections.

    I would not use it. It is a mortar and not suitable for heavy thicknesses. There are lots better products. Mizzou is common and good for making thick sections, but it is not a good insulator. Buy a little Satanite to use for a hot face, it is very easy to use and very forgiving. You really want the thick sections to be an insulating material. Sairbond and Sairset (pre-mixed) are for sticking bricks together and they do really well at that. They don't provide insulation. I think bricks laid loose work the best anyway. Expansion and contraction are going to crack something anyway, the seams between the bricks gives a place for that to happen. A hot face on top of 2,600F insulating brick makes a good furnace, and ceramic fiber behind that is even better. Satanite on ceramic fiber is probably the cheapest and best with a layer of insulating brick on the floor with Satanite on it. Thick Satanite is not good either. Paint it on in a few thin layers.

    Another good hot face is Greencast-94. 94% alumina. Also not a good insulator. But it is good to 3,500F and great for plinths and tuyeres. But it requires an extensive dryout procedure to avoid cracking and spalling.
  17. joe yard

    joe yard Silver

    Thanks for the advice! I am very close now on having things together as far as the basic shape. I did make it to the shop yesterday to mostly finish the lid but still have to cast the burn chamber and a few smaller parts.
    The heat made me a bit sick so I am taking it easy today.
  18. joe yard

    joe yard Silver

  19. oldironfarmer

    oldironfarmer Silver Banner Member

    Maybe it's only the bag.
  20. joe yard

    joe yard Silver

    After looking at the sight. I am more convinced that it is a scam! They sell everything from tape to toilet paper. All for around $20. They must have found that $20 is the magic number.

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