My IFB/fibre-blanket furnace build.

Discussion in 'Furnaces and their construction' started by OMM, Sep 20, 2019.

  1. OMM

    OMM Silver Banner Member

    This is somewhat a continuation of my Kwiky thread.

    I started out with 40 light (3500°F) density IFB’s ( 2 1/2” x 4 1/2” x 9”) and one roll of fibre blanket (2” x 24” x 150” 2300°F).

    I want to build a decagon (10 sided figure). I want everything easily replaced And somewhat capsulized.

    My goal is to keep everything....
    - portable (keeping weight somewhat down and mobile)
    - one man operation
    - keep operational costs to a minimum
    - somewhat rugged
    - furnace being smaller than (24” x 24” x 24”)
    - crucible size, I didn’t care about.
    - burner I wanted simplified and as small as it can be... i’m OK with having two burners.
    - only 1=>15 amp circuit that provides electrical power. So disconnecting one common extension cord would shut down everything.
    - very little, screwing around with mortar, Applicable refractory cement....
    - minimal waste, with minimal work requirement for replacement parts
    - primary heating source being diesel for pre-heat and WMO/WVO being primary heat source

    It became a long list of requirements.

    The simplest, became junk 24” barrel cart. With handle.
    - some stainless 22 gauge steel offcuts for the lid. (I had to plasma cut them)
    - I fit some 12 gauge base with the plasma cutter as well.


    The lids will get drilled as an assembly, and toe clamp the lid IFB’s. I will mortar the lid IFB’s, And add the high temperature fibre wool to the top and sides of the lid.

    The sides and the bottom of the furnace will be lined with IFB’s and lined with the 2” fibre wool as well. The outer shell will be finished with 22 gauge stainless steel.

    All the IFB bricks will be held in place with hose clamps.

    ( yes I, I did drag my big 2200lbs. sander into the driveway for fitting, but files are somewhat too large for this post. )



    The stainless steel straps/hose clamps have a maximum diameter of 17 3/8”

    This is my build!
  2. OMM

    OMM Silver Banner Member

  3. PatJ

    PatJ Silver Banner Member

    Gosh that is a boss-hog of a sander you have there !!!

    Nice brick work.
    I need a sander like that.

  4. Peedee

    Peedee Silver

    I WANT that sander! (Not that I need it I just WANT it!) Looking forward to the rest of the build.
  5. Jason

    Jason Gold Banner Member

    Oh my F that thing is over 5ft tall! What happened to the mortuary brick?
  6. OMM

    OMM Silver Banner Member

    The sander? Yeah it is 54 inches tall( you are seeing it a extra 4” off the ground, pallet truck). It is 64 inches long from end to end, and 30 inches wide.

    The IFB’s? they are leftovers from the new install. I guess you missed a few posts on the kwiky thread.

    The exhaust hole will be just slightly shy of 4”. Any good reason to be bigger? I figure, I can always reduce the size easily if it’s 4 inches or smaller with just an IFB.

    Mark's castings likes this.
  7. Jason

    Jason Gold Banner Member

    4inches is good. Perfect size.
  8. OMM

    OMM Silver Banner Member

    You’re gonna laugh. That is going to be my drain hole size Too. I’m just going to fit it with a brick or fibre blanket. 2 inches of fibre blanket is going to be below the main IFB floor. So my minimum size for plinth, Will have to be bigger.

    When finished, there will literally be four pieces that can come apart by just lifting.
  9. Jason

    Jason Gold Banner Member

    I plugged my drain hole. That's a hole other can of worms around here.
  10. OMM

    OMM Silver Banner Member

    It’s not so much a drain hole, as it part of the design. I wanted the lid to be exactly the same design as the base.

    I only wanted two shapes of brick. But, trying to use up my offcuts somewhat resulted in three.

    I figure the top of the furnace and the bricks that take direct hit from the torch will degrade the fastest. There is nothing I can do at the top, but with smaller crucibles, and I think I can add in a small sacrificial hot/burn face. The top and bottom I might be able to flip.
  11. Jason

    Jason Gold Banner Member

    I had to do that with my furnace, the Mizzou was little thin on the opposite side of the burner and I didnt like the glow I was getting. So I gooped on a few handfuls of strategically placed Mizzou, worked like a champ. Promoted spin and protects the most vulnerable part of the furnace.
  12. OMM

    OMM Silver Banner Member

    I think one of the other oil guys here showed a picture of them reducing the diameter of the Hot face by just loosely setting in bricks. I thought it was brilliant. After seeing the swirl experiment pictures with metal creeping up the inside of the furnace, I came to the conclusion a small sacrificial face might extend the life of a furnace.
  13. OMM

    OMM Silver Banner Member

    Initially, I’m not gonna mortar any of the bricks except for the top ones. I was warned against it by at least one or two people here and the person I got the brick from. The person I got the brick from is guessing that I will have a positive pressure inside the furnace... This will extend to hot gas leaks through the IFB’s. He figures all have about 2 to 3 inches water column pressure inside the furnace. This is where I came to the conclusion of not lining the outside of the IFB’s with rockwool insulation and going with fibre-wool. Rockwool might be able to handle 1200°F, but the fibre-wool can handle 2300°F.

    I know, I’ve been told to mortar everything more than once.
  14. joe yard

    joe yard Silver

    The furnace is looking very nice and moving right along. I especially like the top and bottom being interchangeable.
    That sander is a beast. How many Hp, is it? I think at that weight it would find a permanent place in the shop.
    I have a furnace under construction that has taken way to long. It has fallen victim to the too many other things needing worked on excuse. Translation, I am lazy.
    It also uses a top, bottom and barrel although the top and bottom are very different.
    It has much the same construction as you are building. I started with a commercially made insulating fire brick liner. Then wrapped in 2500 degree wool blanket.
    If I ever build a totally different furnace... The things I would do different would to be first of all build bigger and now that I see your design I think I might want a 4pc furnace with a matching top and bottom, burn chamber and barrel.
    I can not say for certain that a separate dense cast refractory burn chamber will last longer but it was easy to form. I could have used a light cast refractory with a hot face but I had this.
    It is backed by wool. This will be the high maintenance part of the furnace. It would be a big plus if a replacement chamber could be cast and shelved for when needed.
    My burn chamber is convex and is around 2 inches larger in diameter than the barrel. My thought is to have a wide path right under a flat topped mushroom shaped pith. The flame will exit around the edge of the pith in a rather restricted gap between the pith and side wall of the barrel. It is yet to be seen how well this will work on the first try.

    Tobho Mott likes this.
  15. OMM

    OMM Silver Banner Member

    Joe, 4 hp for the disk (8 pole 850ish RPM)and 1.5 hp for the bobbin sander, three phase, 550 V,

    I rescued it out of a local federal penitentiary (woodworking shop) auction. They were closing down the penitentiary. And I picked it up for just over $1200CAD, (maybe 900 USD)
    joe yard likes this.
  16. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I mentioned before, but mortar or no mortar doesn't seem to be a big deal if your bricks are fit well. Do you have the manufacturer of your IFB and a spec sheet. I'd be interested to know their composition. There is another reason to consider quoting your IFB and resistance to fluxes, combustion gases, and metal contact. Most of the common IFB is poor in this regard compared to other refractory.

    You will get spills and splatters from metals and fluxes with use. The guys who build forges often use fluxes and a lot of the coatings on interior forges are there for this reason and durability. The Satanite mortar you often see referenced here has good resistance and bubble alumina even more so. ITC 100 is a popular coating too.

    I used a dilute mortar to coat the interior surface of my original IFB/wool furnace. Beside gas/flux/molten metal resistance, the coating also makes the brick surface considerably more durable. Over many heat cycles it may flake in areas because of the shrinking in initial curing and the constant working between the materials through heat cycle.......but very easy to patch and repair. It'd just maintenance and to be expected with a foundry furnace. Here's an example of the interface stress coatings can induced.

    Dilute Mortar on IFB Warpage.jpg

    Damage caused by flame impingement can be a combination of the heat and gas. That said, I think OIF has a boat load of melts on his IFB brick. I can't recall for sure but he may have coated some areas and just mortared the surface of seems to seal cracks in the lid. I do seem to recall Melterskelter applying bubble alumina to his furnace IFB lid and vent.

  17. OMM

    OMM Silver Banner Member

    this is the best I can do. This was what was on the box. I assume off shore.
  18. Jason

    Jason Gold Banner Member

    That box reeks of offshore cheapness.
  19. OMM

    OMM Silver Banner Member

    Today I welded up the base with the off cuts from the plasma cut to add some strength.

    I added some high temperature red paint (only good to 900°F, But hopefully the paint doesn’t see this).
    Dropped in the base plate.
    Dropped in the fibre wool.
    Dropped on the base IFB’s
  20. OMM

    OMM Silver Banner Member

    Maybe, but I don’t look a gifted horse in the mouth.
    At least I believe the wool New York and refractory mortar was made in Ohio.

    Last edited: Sep 22, 2019
    Jason likes this.

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