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Saving my exercise ball project

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  • Fishman
    replied
    Interested to see how this works out for you!

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  • BristolWFO
    replied
    Update time! Progress has been very minimal past few weeks. Trying to pack, move to a new house, and we have a newborn. Things should settle down in August.

    I was able to parge the dome interior with the Insul Stick. Pretty nice stuff once you get used to it. It didn't seem to want to attach to the vermicrete but giving it a good smear with a gloved hand it went on nice. I was applying small batches but ended up mixing the whole 20lb pail and dumping it in and spending time smoothing it out best I could. I tried to get slightly more thickness on the dome top and sides and back. It's about 3/4" in those areas and about 1/2" up near the door. It dried pretty hard and should add strength to the dome. It's smoother than it looks, the overhead lighting makes trowel edges look worse than they are..

    Next up is moving the dome and base to the new house which thankfully is only about 15 minutes away. Need to cut the floor firebrick and then get the dome onto the base over there.

    So far so good!
    Attached Files

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  • BristolWFO
    replied
    Couple more updates.

    Formed up the dome base and filled with perlcrete. Something weird happened with that mix it came out super crumbly. So I mixed up some thin cement and poured it over and it soaked in through all the gaps. Then parged over it to kind of seal it. Came out fine.

    Got the dome flipped over and going to be lining it with refractory probably later today. After that cut the fire brick for the floor and get those set in sand. Then the dome can go on the base.

    Planning to taper the chimney opening for smoke flow. And I plan to make the chimney hole larger it's a bit too small.
    Attached Files
    Last edited by BristolWFO; 06-26-2020, 07:57 AM.

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  • BristolWFO
    replied
    Quick update - haven't had much time to work on the oven, got a lot going on. I was able to get the stand top done. 1/2" backer board on the bottom and 3.5" of vermicrete on top of that. Next will be a base for the dome to sit on and open in the middle for the firebrick. I'm going to keep the firebrick "loose" so broken ones can be replaced if it happens. The InsulStick came yesterday and ceramic blanket due today. I went with 1/2" blanket, I'm not looking to go crazy and it was cheaper. I may have enough to double it up and will if I can. But being the dome is vermicrete I think that's decent insulation. Then need to figure out what to render with.
    Attached Files

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  • BristolWFO
    replied
    I understand and agree, however as I mentioned when I started this stand I was renting a home. So I could not build anything permanent or anything I'd be fine with leaving behind. So the stand will do for a while until it gets to its new home in a couple months.

    I was wondering about stability but the stand is rock solid and is larger than it might appear. Its 4 feet by 3.5 feet. Not going to tip over even if a wheel pops off. The casters are rated for 330lbs each so I'm pretty confident I'm way under 1300lbs total. If I calculate up all the material weights the oven and base are in the 350lb range. Larger wheels will only serve to raise the center of gravity. I may add some cable cross bracing with turnbuckles if I feel it needs it.

    You cant see in the picture but the horizontal cross beams on top are also supported inside by Simpson joist hangers. Not just the 2 screws you see on the outside. According to the mfg load tables they are rated at 200lbs load each end. I have 6 on there. The checked in ones are loose to be slid out and replaced with a long beam to move the entire top.

    I dont plan on wheeling this thing all over the place, it will sit on one spot until moved to the new house where I'll make a permanent stand for it. Hence the knockouts to be able to lift and move the oven off the wood stand. Until then it will be stored in a garage out of the elements.

    I'll keep posting updates for anyone who's following along!
    Last edited by BristolWFO; 06-03-2020, 12:24 PM.

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  • david s
    replied
    Timber is generally not recommended as a material for an oven stand as it moves with moisture. Any movement will be transferred to the heavy brittle material it supports. If the stand is out in the weather this problem is far worse. I have no idea what size oven you plan to sit on top of the stand. Have you calculated or estimated its weight? They nearly always turn out to be heavier than you’d think. Movement of a timber stand, especially one that is mobile, can be reduced by the addition of diagonals. Small wheels also increase the danger of movement or at worst collapse because of the high centre of gravity if the wheel strikes a bump. Your horizontal beams appear to be only held in place by a couple of screws, or in the case of the ones checked in reduce the beam thickness by half.
    On rereading your thread I see you’ve already cast a lightweight dome, so maybe you’ll get away with your stand, but at least change to large wheels for safety and add diagonals for strength.
    Last edited by david s; 06-03-2020, 12:01 PM.

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  • BristolWFO
    replied
    Update - I ordered the Insul Stick, waiting for that to arrive. Been working on a stand for the oven. When I started it I needed it to be on wheels since I rent a house and cant make something permanent. But last week I have a down payment on a house so the wheels will help me move it to its new more permanent home!

    If you look at the top deck supports there are 2 untreated 2x4s sitting in notches. Those are not secured and will be able to be slid out and replaced with longer 2x4s to act as handles for 4 guys to lift and move the whole top. I've built an upper wall and will be filling with vermicrete soon.

    That's all for now!Click image for larger version

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  • david s
    replied
    No, I don't think you should on such a thin layer. You don't want any needles close to the surface and it will make application of the stuff that much more difficult.

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  • BristolWFO
    replied
    Thanks Petter and david s
    The supplier contacted the manufacturer of Insul Stick to check on it and they said that the contents are really no different than firebrick, regular brick, concrete and mortar. All containing silica which as you guys pointed out has the danger of inhaled dust and handling of the material when applying.

    Given that I think I will give it a try. Should I add melted extract needles as well for strength during heat & cool cycles?

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  • david s
    replied
    Yes the silica is locked in. Pretty much all refractory material, clay and concrete contain silica, but it’s only a problem if you inhale large amounts of it over a long period. Inhalation is the problem not ingestion, so it’s safe to use for an oven. Eg. Breathing clay dust indoors is bad, sanding fired clay indoors really bad especially for children. Dangerous activity is cutting or grinding, especially if done dry, as tiny shards of silica material damage the silica in the lungs.
    Last edited by david s; 05-28-2020, 02:27 PM.

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  • Petter
    replied
    Originally posted by UtahBeehiver View Post
    I read the MSDS and I am not sure I would want this material inside the dome where the food is cooking. I suggest you reach out to David S on parging the inside of a vcrete dome although I know from past post he believes that most applications will not work or fail.
    and BristolWFO,

    I believe the MSDS apply the non-cured product. Any hydraulic setting agent will be hazardous due to the reactivity and high pH if in content with water.

    Unterminated Si-O bonds in crystalline silica is what causes lung cancer if exposed over time. If in a mortar/casting, the silica is locked in and covered by the reaction products of the CAC and water.

    Have I gotten this wrong or can someone please explain?
    Last edited by Petter; 05-27-2020, 09:33 PM.

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  • BristolWFO
    replied
    You're right UtahBeehiver, that looks like some nasty stuff. I will pass on that!

    I was also looking at the "ITC-100HT Pint Ceramic Radiant Heat Reflection & Protective Refractory Coating". That goes on like a thick paint or a slip. Thinking maybe that would sort of seal the vermicrete and prevent spalling. It has good flexibility for expansion too. But it has a warning in its MSDS as well but not sure if that's for before curing only.

    Then insulate and render.

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  • david s
    replied
    There are many different castable available from many different manufacturers. You need a dense castable not an insulating one. The product you linked to might work, but anything applied in a thin layer is likely to crack, so make it as thick as you can. Also the substrate it’s applied to needs to be somewhat damp. Too wet won’t work, too dry won’t work. Cover it for at least two days to retain moisture while the stuff hydrated. Calcium aluminate based products cure in 24 hrs, but best to give it 48. Good luck, I hope you can save your casting.

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  • UtahBeehiver
    replied
    I read the MSDS and I am not sure I would want this material inside the dome where the food is cooking. I suggest you reach out to David S on parging the inside of a vcrete dome although I know from past post he believes that most applications will not work or fail.

    Leave a comment:


  • BristolWFO
    replied
    One company that sells refactories sent me this link as a possibility for a dome liner:

    http://www.heatstoprefractorymortar....?INSUL-STICK-5

    Not sure about it...

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