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Thread: Tobho's new furnace build!!!

  1. #1
    Senior Member Tobho Mott's Avatar
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    Tobho's new furnace build!!!

    Been working on a new furnace. I figure my 8" bore Gingery-style charcoal furnace works great, but I've been using it for lost foam aluminum casting for coming up on 2 years and so it's about time I built something a little bigger. With proper refractory and insulation and a tangential tuyere, to give me a bit more versatility and allow me to play around with a burner...

    I got a couple of 30 gallon steel drums which are about 18" diameter, so I have my outer shell.

    I got 3 50-lb bags of Unicast 70 dense castable refractory rated at 3200F, so I have my refractory.

    My 2600F rated ceramic blanket and insulating firebrick will have arrived at the pottery supply shop today, so I will soon have my insulation.

    I decided to follow the example others have set and start by building a cart for the furnace to sit on and get rolled around on. I used 1" square tubing for the frame and an unfolded sheet metal oven drawer that I hung onto when my yard-oven finally went off to the dump with its friend the yard-fridge to build the platform. Since I don't have the equipment or the know how to fabricate it by welding, I had to use a combination of nuts and bolts and pop rivets and brackets. It doesn't have wheels or a handle yet, and the bit of extra metal protruding off one side needs to get trimmed off, but I'll get to that soon enough. Here's the cart so far, I think it will work out well; I built it longer than the furnace will need so that I have some extra room on it so I can wheel some of my other gear out into the back yard with it..

    image.jpg image.jpg

    I also cut out some (3) legs for the furnace itself, and notched them so they can be welded flush to the sides of the barrel without the protruding rim of the bottom interfering. They will allow it to sit up above the cart so I can slide an ingot mold under the bottom drain in case of spills or attempts to direct melt larger scrap.

    image.jpg image.jpg

    Also cut out most of the pieces for the lid lift/swivel mechanism, other than a pedal and lever.

    image.jpg

    From top to bottom:
    - 1" pipe for the upright part that will be raised up when the pedal is depressed
    - 1-1/4" pipe hinge for the lid. I probably won't use the 3" nipple in the pic, I have a long piece I will use for all the 1-1/4" stuff but it's not in the pic.
    - 2" angle to connect the lid hinge to the lid via welding.
    - upper flange, will be bolted to the 1" pipe so it will push the lid hinge and angle upwards when the pedal is worked.
    - 2" angle to connect more 1-1/4" pipe to the furnace body to hold the 1" pipe steady.
    - lower flange will be bolted to the cart. The 1" pipe will pass through it and a hole in the cart to rest on the lever the pedal will raise so it will lift with it.

    A friend who is pretty interested in my hobby is getting in touch with his brother-in-law who owns a welding machine and will hopefully be interested in helping. If not, there's a guy just down the road who is pretty nice and has made a welded steel crucible for me before as well as the stand and grate for my 55 gallon wheel melter. Wish I could do it myself.

    I have built a moya waste oil burner, but so far I have only tested it on propane (to do 2 aluminum melts in a ring of old house bricks) which will be used to preheat the furnace. Old pic, not quite complete as the propane line wasn't installed yet when it was taken, but it is fully built now. I have a bucket max shop vac for a blower, and I still have my hair dryer that I use in my charcoal furnace, which worked well when I tried burning propane.

    image.jpg

    Ack! Upside down pic...

    Last but not least, I have some 14" wide duct tubing left over from making the shell of my charcoal furnace and a 12" sono tube to use as the forms for the castable hotface. Ie. it will have a 2" layer of ceramic fiber and 1" of castable surrounding. 12" bore. I plan to insulate the floor with the insulating firebrick underneath some castable for stability and the walls and lid with the ceramic blanket. I'm considering using one brick in the wall where the tuyere will pass through for a bit of extra stability there - a good idea or not?

    I think that's about all for now, I'll be working on it whenever I get a chance and will try to update regularly. Comments and suggestions are welcome, ideally when they arrive in time to stop me from making some stupid mistake!

    Jeff
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos

  2. #2
    Senior Member metalbynevin's Avatar
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    looks awesome so far, Jeff! I will look forward to seeing it when done
    "Nothing is foolproof to a sufficiently talented fool!"

    Lost foam cast aluminium - http://www.alloyavenue.com/vb/album.php?albumid=104

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  3. #3
    Senior Member caster's Avatar
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    Good work Jeff,

    When I refaced my furnace I used a 3" pvc pipe as the mold for the tuyere. I did not have my oil burner built nor knew what I was going to use for a burn tube but I thought 3" would give me flexibility. For my propane burner it was easy, I cut a 1 1/2" hole in a piece of sheet metal and placed it over the tuyere attached with magnets. This closed the hole so the burner fit well. When I built my oil burner it was 2 1/2" diameter. I thought that slack in the tuyere would not matter but I had flames and hot gases shoot out of the hole. I took some 16 gauge sheet metal, figured out the circumference of the burner added 1/4" and cut a 6" x C+1/4" rectangle, folded it over the burner and welded it into a 6" tube. Its tough to weld thin stock without burning through it, I used the lowest power setting, the lowest wire feed, tacked then welded 1/4" at a time so as not to over heat the metal. This was a near perfect fit for the burner. I used 3000F furnace cement to secure the tube in the tuyere. It made a big difference both in eliminating the escaping flames and how the flame formed in the furnace. If you know your burner size you may want to have your welder friend make a tuyere tube for you as well.

    Interestingly the escaping gases made the burner holder too hot to touch but the burner tube was cool to the touch. The blower and compressed air kept the burner cool.

    Good luck and keep the pictures coming,

    Caster

    p.s. when magnets get hot they stop being magnets. I should have known that, when hardening steel you heat it until it loses its ability to be magnetic.

  4. #4
    Senior Member Tobho Mott's Avatar
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    Nevin - thanks... me too!

    Caster - Yes, I am planning on having everything that needs welding ready to go so all the welding can be done at once, including a tube for the burner to fit into if I can't figure out a way to attach it otherwise..

    It's a 1" burner tube. I'm actually using a foot-long tube (ie. longer than the one pictured) as well as being made of black pipe rather than galvanized.

    The moya is an oil drip burner similar to Lionel's Hot Shot design which is used by Rasper here in a similar sized furnace with good results, so I really hope this will work well for me too. It was very easy to build; other than tapping a hole for the propane line to screw into, it was really just a matter of twisting threaded bits together and a little bit of hacksawing to make the drip tube end where the burner tube does. But I may make the tuyere big enough to fit a bigger burner just in case. Obviously I'd have to plug up the gap between them somehow. I haven't really completely thought that part through yet...

    Jeff
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos

  5. #5
    Senior Member cactusdreams's Avatar
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    Sweet! Go man, go!
    People who say it cannot be done should not interrupt those who are doing it.

  6. #6
    Administrator Site Admin
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    Yes, always make your tuyere big. Making it larger later on is hard. (Don't ask me how I know.)

    I just stuff some mud around the burner in the tuyere before I light it. (This ain't rocket science.)

    Richard
    When I die, Heaven can wait—I want to go to McMaster-Carr.

  7. #7
    Senior Member Tobho Mott's Avatar
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    LOL, I don't think I need to ask how you know, I bet I can guess it right on the first try!

    Using mud would never have occurred to me! Good tip, thanks. Someone recently posted in another thread about casting refractory bushings to do the job, but your way sounds a lot cheaper and easier.

    I do hope my burner will seem at least a bit rocket-like....

    Jeff
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos

  8. #8
    Senior Member Tobho Mott's Avatar
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    Added wheels. And only lost a tiny bit of skin off my knuckles this time. Count the scars on Tobho's hands and you will know how many projects Tobho has taken on. Don't know how well they will work out in the yard under load or how long they will hold out, but they once worked fine on my old bed, so I'll give them a shot for now and replace them later if need be. (Other parts of that same bed frame now make up the stand for my bulk melter, but I had to get that one welded rather than put together myself after ruining a couple of drill bits trying to drill holes for bolts in the rails I had cut to length with my grinder. I DIY what I can but there are limits.)

    The existing holes on the diagonal supports for the wheels happened to line up with the existing holes in the corner brackets. Convenient!

    image.jpg

    Didn't get much more done this weekend, had family visiting from out of town to entertain. Anyhow, I'll continue fumbling my way along as well as I can and keep posting as I go.

    I'm sure many of you can tell I haven't done much of this kind of work before. Casting has all these related skills that come into play and teaching them to myself as I go is a big part of why I enjoy this hobby.

    That, and just being able to go out in the backyard and melt some $#!& from time to time...

    Probably picking up the insulation this Wednesday on the way home from work. They have it in, but that is the soonest I can get there. I still have to finalize the design details of the furnace itself and measure and cut the barrel to size before I can start installing insulation and refractory anyhow. Plus get the welding done for the lid mechanism. Next couple of weeks sometime is looking promising for a trip to buddy's sister's place to happen for that part.

    Jeff
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos

  9. #9
    We gotta dig you up a welder man. Saves TONS of time being able to just tack stuff together for mockup. If you were closer, I'm sure I could dig one up for a song! Your setup looks good. Creative use of bed frame rollers!
    Jason
    Visit me: WWW.HandcraftedLanterns.com
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  10. #10
    Senior Member Tobho Mott's Avatar
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    Yeah, I'm checking kijiji and usedottawa.com now and then and keeping an eye out for sales. I really have no clear idea how much welder I need for stuff like attaching 2" angle to steel drums and 1-1/4" pipes or making cart frames out of 1" square tubing though. Or how to use one or even what kind to look into getting. I probably wouldn't need to use it that often or that much, so I guess cheap to get into and simple to use would be a big plus for me. As opposed to cost per inch of weld or however it would be measured. I will ask my friend's brother in law a bunch of questions about all that when I get a chance to drop by and do the welding, and hopefully I will get to try my hand at it myself as well.

    I'm also trying to save up to buy a generator, which doesn't help. Just sick of having a flood in my basement every time the power goes out for more than a couple minutes. The top of the motor for my oil furnace burner (home heating type, not foundry) was an inch underwater the weekend before last within minutes of the power going out during a huge storm when there were local tornado warnings. It usually doesn't fill up that fast, but the sump does kick on regularly all year long in my hundred year old basement. Luckily I am on the service plan with the oil company so the motor replacement should be covered. It was covered the last couple of times this happened... Usually it's just me but the neighbours had the FD out to pump out their basement too that day, so we got them to do ours as well as it would have taken the sump a day and half to empty it out most likely. luckily I don't keep anything valuable down there. I'll probably have to throw out a few boxes of the kids' old stuffed animals, that's about it. Thought they'd be safe up on 2 pallets but they got wet too... Just found out my son's friend's dad has an extra working generator that just needs a new pull cord, maybe I can get a good deal from him that will leave me a little something for the welder fund. Gotta worry about the wife's birthday first too though; dead men weld no lid-lifters!

    Feel free to make and discuss any suggestions about welding here meanwhile; it may be very helpful to me, and I'm not going to have anything more to update on the build until late tonight at the earliest anyhow, so I can drag this thing back on topic if need be when I have more to add.

    Thanks,

    Jeff
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos

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