Starting build with 30 gallon barrel

Discussion in 'Furnaces and their construction' started by Bentation Funkiloglio, May 23, 2020.

  1. Melterskelter

    Melterskelter Gold Banner Member

    Just buy it and save it for your next furnace. ;-) There will be a next one. No furnace lasts forever with iron!

    Denis.
     
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  2. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I think it would be a great discussion....and probably worth it's own new thread. If heating was uniform, segments really shouldn't fair any better than monoliths......but if heating is not uniform.....not so.

    Best,
    Kelly
     
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  3. Petee716

    Petee716 Gold Banner Member

    Agreed. I've unexpectedly found myself needing to replace my plinth and pedestal as well as recline my floor because of a crucible failure. I'm glad I have a supply of Bluram. If it's an option, I have some mizzou that might be enough to get you by. I dont know if youd have compatibility issues. I'd be glad to be rid of it though so I can use the bucket for something else.lol!

    Pete
     
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  4. @Petee716,
    Just weighed my remaining refractory and have 5 3/4 lbs left which is more that
    I thought. Will be a tad on the thin side but can probably get by with that amount.

    However, if you really want to free up that bucket space, let me know how juch shipping will cost and I'll have a buddy PayPal some money to you. I don't trust the Internet, so don't have my own account. :)
     
  5. So, what do you all think about the following plan for furnace lid build? See highly technical drawing and associated comments. Any/all feedback appreciated!

    Furnace lid build visual.
    artflow_202006031528.jpg
    Description:

    Turns out that I have a couple old 12 inch diameter gold pans that have a nice and useful shape. So ...

    1. Cut bottom off of one of the two gold pans

    2. Make annulus form that will fit into the opening in gold pan caused by step 1. See pic. The outer wall of that form will need to be a 3/4 inches shorter than the inner wall.

    3. Create a 3/4 inch cardboard gasket. Not shown in pic. This gasket will be placed between the two gold pans to create and seal a 3/4 inch cavity between the pans when one is placed on top of the other as shown in pic.

    4. Place golds pans together with gasket in between them. Gold pan with bottom removed is on the top. Gasket runs along the outer most perimeter of pans. Note, oil up gold pan surfaces as release agent.

    5. Pour refractory into cavity created by putting the two gold pans together. Refractory is poured through the hole in top pan. Need to leave space for next step, so do not fill cavity completely

    6. Place annulus form into opening in top pan ensuring that is securely attached. The form's inner wall must go all the way down to upper side of bottom pan. Since the outer wall of form is a bit shorter than inner wall, the cylinder created by form will be connected to the rest of the lid.

    7. Pour refractory into annulus form. When dry, this will create a hollow cylinder attached to a domed lid.

    8. Allow refractory to dry for 24 hours.

    9. After drying, remove bottom pan and gasket. The other parts of the form will not be removed in one piece, probably.

    If all goes well and I didn't miss something, then I should end up with a domed lid for furnace with a refractory chimney that reaches the top of the lid's metal shell.

    I haven't yet decided best way to secure refractory to metal shell.

    What could possibly go wrong? :)
     
  6. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Your forms not releasing from tenaciously bonded castable refractory........You need to experiment with parting compounds. I use a couple coats of paste/carnauba wax. If the surfaces of the mold are smooth, this usually works well. Others have used Petroleum Jelly with success. Better come up with a high integrity manner to keep your pans sealed and held in position.

    Best,
    Kelly
     
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  7. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    You may also want to give it more than 24hrs before demolding.

    Though the refractory is supposed to kick simply from the reaction initiated with water (and it does), the tendency to have wetter than intended mixtures, air tight molds, and cooler temperatures can significantly extend curing times for reasonable green state strength. Doing a great job molding, mixing and casting can be followed by a big let down when you discover you did a perfect job molding and casting only to break the green part when you demold. Gentle heat can make a big difference in initial cure speed and green strength. a 100w incandescent bulb inside the mold can really help.

    If ambient temp is warm, say >80F that may not be necessary.

    I've cast some pretty thin structures and sometimes pulled one side of the mold and then let it sit for another day.

    Best,
    Kelly
     
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  8. @Al2O3, good call on the mold. Based on your comments, I see that I'll need to sand ridges and fill depressions found in gold pans. Might look for alternative objects if it turns out to be easier. I'm pretty sure that we have an old wok sitting around here somewhere. The wife won't mind ...as long as I also buy her a new one.
     
  9. Made a great mold using 12 inch frying pan lid for shape. Unfortunately, over-vibrated which made area around opening too thin. Most of material moved down around edge.

    Live and learn.

    Hoping that my local peeps will be able to sell me some plastic refractory, so I can get started with heat curing this weekend!
     
  10. Been heat curing furnace refractory. I am so incredibly happy that I mixed the mizzou as dry as possible, vibrated it into place, and then let it dry out for over a week. Lid is the exception and have to redo, since I ran short on refractory.

    Put the plinth in furnace as a canary. It's in path of flame and probably gets most heat, earliest. If it started to crack, then I'd have backed off on the heat up before problems arose with furnace walls or floor. That was the plan, at least.

    Bottom line, perfect. Not a crack.

    As an experiment, I put the partly finished lid into heat as well. It had only a couple days to dry out. Lot more water was still in refractory and got a couple small cracks.

    Can't thank you all enough for your great advice!
     
    Last edited: Jun 7, 2020
  11. Apologies, I have another very noob question. Please let me know when Ive hit my yearly quota:)

    I'm having a difficult time getting lid into desired shape.

    Would a lid made from 2600 F ceramic blanket be adequately durable for iron work if furnace facing material was covered in 1/8 inch itc-100 ht?
     
  12. Melterskelter

    Melterskelter Gold Banner Member

    My best guess is that your experience would be similar to mine using Satanite over 2600 wool. It worked pretty well for the first ten or so cycles with only slight maitanence. Then it got worse. BUT, you might fare better with 20 to 30 Deg doming and no chimney to deal with. Iron punishes wool/Satanite and then you also have the gravity factor that lids must defy. My side walls of Satanite/wool has held up better. But the recent wool experiences are what is spurring the segmented plastic approach. Wool I expect to be well protected by plastic refractory. We shall see. The lid so far seems very durable.

    Denis
     
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  13. Hrmmm, yeah. I guess that I’m not too surprised that a thin coat of itc over fiber wouldn’t be terribly resilient. However, thought that I’d ask in the event my concerns were not well founded.

    One of the difficulties that I was having was creating a thin dome, inch or less thickness, with plastic refractory. Had 2 failures where refractory cracked and then fell apart. I better understand why you decided to make a segmented lid now that I’ve been messing around with it myself.

    Just started heat curing my third attempt. Glad that I bought 2 boxes of plastic refractory!

    I added more heft for this attempt. Also, an old stainless steal serving bowl (as dome form) allowed me to create a nice dome shape. Down side is that it will not be light. Added 8 anchor points to ensure that dome stays put.

    I still want a 6 inch chimney. Maybe worth trying itc over fiber for chimney.

    this is what third attempt looks like.

    835FFCC4-938A-43EC-8A70-182D6E911145.jpeg
     
  14. So far, going pretty well. Stainless steel serving bowl is out. Continuing to heat cure slowly.

    B0EB196A-C699-4359-AA2D-5A53CCC50FBC.jpeg
     
  15. And, here we go. A self-supporting dome for furnace lid. Hopefully, it will remain in one piece while it cools down.

    B26D5C02-BE85-490D-9E52-AB4FA9179EC8.jpeg
     
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  16. Tobho Mott

    Tobho Mott Gold Banner Member

    Looks good to me. That blue ram stuff seems like a good alternative to casting refractory shapes like this in 2-sided forms.

    I took advantage of one of the ribs in my 18" oil drum to lock my (cast) U-profiled non domed lid hotface inside the steel, with some kinked 1/8" stainless rod lengths hashtagging across the refractory to help hold any big chunks together in the event of cracking... Hopefully a little more than they promote such cracking. I never saw any cracking in the lid that I can recall through several years of admittedly casual use, but it's been a while since I got down on the ground to take a peek at its underside.

    Jeff
     
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  17. Yeah, it's really sturdy once heat cured. Seems to be harder, more rugged than mizzou. Don't know if this translates to longer operating life.

    I think this material would be perfect for making slabs, bricks, etc. that are joined together with high temperature refractory mortar.

    I don't think that this variety of plastic refractory would be good if precision is important. It's chunky and must be rammed into place with a decent amount of force.

    My experience suggests that this refractory is really sensitive to uneven heating, which could complicate the construction of complex monolithic shapes. I had to take some special precautions to ensure even, slow heating. I didn't heat refractory directly at first. Instead, I placed it on top of sheet metal and heated the metal. Did this for probably about 80% of curing time.

    All in all, pretty good stuff once you get used to it.
     
  18. Melterskelter

    Melterskelter Gold Banner Member

    I am a bit surprised to hear you are experiencing difficulty with uneven heating. The reason I say that is, so far as I know, there is no heating schedule for this refractory as opposed to castable. In fact I made a couple small repairs to my furnace floor and wall using Blu-Ram just to see how it would tolerate abrupt heating. So, I simply pressed it into place and 10 minutes later lit my furnace full force and did a 2-hour iron melt. It suffered no evident ill effects. Similarly I smashed out a deck-of-cards-size piece of it and turned my Mapp gas torch on it wide open. It it was red in 5 minutes or so and as hard as stoneware and extremely strong. I could not break the 1/2” thick slab holding it in my hands between fingers on one side and both thumbs in the middle on the other.

    That strength and toughness was what encouraged me to begin making the mold for my segmental furnace walls 14” dia and 19” high and segmental floor. I think the walls will only be 1/2” thick and the floor not much more than that. The mold for the walls is 2/3 complete. I will start a thread on that build soon. Right now I am too busy thinkin and buildin Though I am trying to grab a few pics along the way.

    Anyway, please let us know what you have seen with uneven heating.

    Denis
     
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  19. @Melterskelter, WRT uneven heating issues, main concern/problem was cracking leading to structural failure. I think that this was the reason that my first two attempts failed.

    While the refractory that I’m using is very, very similar to Blu-Ram, it is made by a different company. This could be the difference.

    My refractory came with a heat up schedule printed on box. Something like increase heat by 75F up to 200F. Hold at this temp for one hr per inch thickness. Then, increase heat again to 500F and hold for 1hr per inch thickness. Then, do same for 1000F.

    I didn’t really follow the above schedule. I just focused on uniform, slow heating.

    Shape design might be a slightly more probable cause for performance differences. From your comments in a past posts, sounds like you are creating more or less uniform shapes. You then use these as parts in a larger project.

    I created one large monolithic shape with variable thickness throughout. The larger size and varying thickness makes uniform heating more difficult. Non-uniform heating might be problematic WRT material shrinking/expansion during heat curing.

    I think that the potential for spalling would be my only concern if I was patching with material or creating a relatively compact, uniform shape. In such a case my experience would probably be more similar to yours.
     
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  20. Petee716

    Petee716 Gold Banner Member

    I found the instructions for the product Ben used, which appears to be essentially the same as Blu-Ram hs, and saw that the dryout schedule resembled that of castable but we have to bear in mind that normal installation of this material is measured in multiple inches and sometimes feet so even though the porosity of the material lends to rapid drying, thicker applications warrant more careful drying. Part of those instructions even recommend combing the surface as opposed to troweling or slicking so as to not obstruct the outward flow of moisture. I was given the same advise with the blu-ram. As an aside those same instructions also recommended using an aluminum ram head instead of steel so the material doesn't stick to the head.
    I recently made a new pedestal and also a 8" diameter x 1" thick disk out of ram and chose to dry them out before firing them. It just seemed prudent. I wanted to try to make sure the disk remained flat, which it did. By the same token I've re-lined my furnace floor once before with it and directly fired it with no negative effects.
    As a side note this stuff is ready to use right out of the box with no additions but the supply I have is beyond its recommended shelf life so it can get a bit stiff. It still moves ok under force but I spray a tiny bit of water when necessary especially when I'm filling cavities. I'm sure there are good reasons not to overdo it with the added moisture but I've had no negative results so far.
    Nice job on the lid Ben.

    Pete
     

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