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Post by cannyfradock on May 5, 2014 18:14:13 GMT
Darrell Great job you've done on the support walls. You could build a 12 story block of flats on top of those walls. Not sure what you mean by.. "I noticed someone mentioning that they watered the hearth during the week, is this a necessity and what does this do exactly and how many times"..... this may have referred to the dome concrete slab?....when a concrete slab is poured, poly membrane is often laid on top to stop the water evaporating too quickly from the slab. In dry hot weather sometimes concrete is "hosed down" the day after to give it extra strength...I'm not sure what your comment refers to. Terry
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Post by darrellme on May 5, 2014 19:57:24 GMT
Cheers, I was thinking I could move into it should the wife throw me out of the house haha.
That was it exactly, its the top slab, i.e. the hearth slab that I was referring to. I noticed someone had mentioned that they had been watering their slab of concrete, so I'm guessing that was the reason why so thanks for clearing that up, I'll probably do that then when I get the top slab poured, hopefully next weekend then give it a good soaking on the Monday.
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Post by darrellme on May 11, 2014 19:51:43 GMT
Didn't make as much progress as I was hoping to this weekend, 1) mainly due to my own stupidity in not realising that builders merchants (for the most part) appear to close on a half day on a Saturday, so couldn't pick up the cement mixer, and 2) framing the hearth and cutting the ply platform was trickier than I thought it would be, 3) realised after creating the first variation of the ply supporting platform for the hearth that I'd have to re-think it if I wanted to be able to remove the ply after the hearth has gone off. Had to make it from smaller pieces instead. So looks like I'm going to have to spend some of my lunch times doing little things finishing off so I'm ready to pour the hearth before the end of the week. Also took me a while to figure out how to get the stupid ratchet straps working properly, with much pinched skin later the hearth is now framed, ratchet strapped in, just need to finish the rebar, paint some diesel on the ply to stop the concrete bonding and tape the ply joints and I'm ready to go
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Post by darrellme on May 14, 2014 21:54:22 GMT
Well, that was a fun evening. Though hiring a mixer would make it easier and quicker to pour the hearth......I finished at 10.40pm headtorch donned and everything. A question though. I was just short of enough concrete/ballast to reach the top of the frame, would I be ok to complete that in the morning or something, will this affect the strength of the hearth or will the new cement not bond to the existing cement ?
Thanks, I hope that makes sense as I'm exhausted so it may not
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Post by darrellme on May 16, 2014 17:41:01 GMT
Well, finally managed to get the hearth finished, I added some more cement in the morning to the hearth, which was tricky due to the stones in the ballast, but finally managed it. The rebar standing proudly on the stands (can't remember their correct name) The hearth finally poured after a very late night and early morning to finish it off. Its not the smoothest of finishes but the idea is to use some tiles to match the slabs in the garden on the parts that aren't covered by the oven itself Need to order the firebricks, fibre board, etc so I guess its a call to Kilnlinings for me, hopefully get the stuff delivered before the bank holiday weekend so I can start on the fun bit D
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Post by darrellme on May 19, 2014 13:56:21 GMT
Hi Terry or anyone else obviously :-)
Quick question, I've ordered the firebricks etc from Kilnlinings but I've decided I'd rather try the homebrew than the premixed stuff, mainly because I don't know how good I'll be able to get any cuts on the bricks, or whether I can actually be bothered to cut them all, so, with that in mind, I know the ratio of the homebrew is 6:1:1:1: (sand, cement, hydrated lime and fireclay), but I was hoping for some advice on the amounts I'd need to buy to do the bricks and then coat the outside prior to putting on the insulation blanket. Also how much would you normally mix at one time, I guess I'm asking the working time of the homebrew (how long before it starts going off)
Many thanks
D
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Post by docfester on May 19, 2014 19:38:44 GMT
Hi Darrell,
A substantial build you have there, looking good.
I'm no expert but having just got to the final part of my build I can at least give you my info. I used the same HB mix ratio 6:1:1:1 as you intend and although I bought 2 bags of fireclay I still have 1 whole bag left. 1 x Hydrated lime which although is almost used up was in fact used on the brick base also and not sure on the cement.
I mixed a bucketful of HB at a time, basically one of the above mixes and this allowed me to use it up at the pace I work at. I found that if the HB starts to dry in the bucket you can actually add small amounts of water which seems to re-activate but working time of around 1 hr seems normal. You will find the right consistency for you after a few batches and its good stuff whoever came up with the mix is a saviour.
Keep posting the progress.
Pete
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Post by cannyfradock on May 19, 2014 20:29:55 GMT
Hi Darrell
That's some great first-hand feedback from Docfester. Good call btw in NOT buying the ready mixed fire-cement......exactly as you said....if the joints or perps are larger than about 4 or 5mm the stuff will never harden.
I only build ovens as a hobby but when I do it's usually for communities or groups so any invited guests get a trowel shoved in their hand and get told to "muck-in".....so I half fill a domestic cement mixer of the homebrew by volume of ratio.....then it's head down and arse up and start laying. As far as quantities go...I use the same as Docfester....I usually have 1/2 a bag of fire-clay left over from 2 bags. After about an hour any homebrew that's left over ...I also add a little water to refresh the mix, then parge up the outside with it.
If you are on your own...or maybe with 1 helper I would follow Docfesters advice......it's spot on.
Terry
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Post by darrellme on May 20, 2014 12:28:11 GMT
Awesome stuff, thanks for the info guys, much appreciated. The other thing I was wondering was either forms or I.T tool. I'd like to use the I.T tool so that I can make sure that the internal is cleaned as I go, and although it looks pretty easy in terms the tool itself, there's no real details in how to create one so I thought I'd pick the brains of those more experienced. From my reckoning the dome height is going to be half the width of the dome, therefore the dome is 36" so the height will be 18". So if I measure the length of the tool as 18" (minus the thickness of the ply that its attached to. In terms of the bracket/l-shape on the end am I right in presuming that it should sit comfortably on the edge of the first row of bricks, and if this is the case then every subsequent row of bricks will be at the correct distance ? Does that even make sense haha
Cheers peeps
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Post by cannyfradock on May 20, 2014 13:36:44 GMT
Darrell
Your calculations sound spot on to me. I would also like to hear any tips from members who have rigged up an I.T....as I must also use one for the first time....on the 31st May. There are some good photo's of making an I.T....posted somewhere on the forum. If I find them, I'll post them...or if you find any please post them.
As the arch/dome transition sometimes is slightly outside of the perfect circle I was thinking of fixing an L bracket on the end of the pivitol arm with groove/slit cut into both the end of the arm AND the L bracket. I would fix these together with a butterfly nut, making the arm easily adjustable in length...if needed. (just my thoughts)
Terry
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Post by darrellme on May 20, 2014 17:12:10 GMT
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Post by docfester on May 21, 2014 6:32:12 GMT
To be honest the Indespensible Tool I made was basically a hinge, wooden base, length of timber with a block on the end and that was it. The FB links above do seem overly complicated for what is essentially a measuring stick. Seen the same method using something as simple as a piece of string or metal rod. Just need to find the middle of the oven and fix the hinge pivot to a piece of wood directly above that. Measure out to the oven wall (soldier bricks) and fix a block to the end where the timber rests against the brick. I marked the timber base and oven floor so everything would line up each time the I.T. was removed for pointing. Hope that helps Pete
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Post by darrellme on May 21, 2014 7:23:33 GMT
Cool, cheers docfester, you're right some of them do seem overly complicated and some down right ingenious.
A quick question to Terry or someone else. I've just put a straight edge on the hearth and it appears to dip slightly in the middle, possible because the stupid thing is so big that I couldn't get to the middle very easily. Is it worth mixing up a little more cement and putting it on the hearth before I start with the dome ? would that work or should I not worry too much about it ?
Thanks
D
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alun
valid member
Posts: 55
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Post by alun on May 21, 2014 9:21:23 GMT
What docfester said. There is so much info out there on the internet now (especially FB). Sometimes I really think people overcomplicate things. Unless you are a perfectionist the margin of error in which you can work is actually pretty big. I spent far too long thinking about things rather than just getting on with the build!
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Post by darrellme on May 21, 2014 17:30:59 GMT
Haha, sounds like me all over Alun
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