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Post by khylen on Apr 25, 2017 22:14:07 GMT
Hi All So like many others, I am finally getting around to it and building the oven that has been in my head for a while! I have had the tree trunk now for about a year so thought it really was about time I got myself into gear! I have dug in the tree trunk slightly and placed membrane under it to stop any water soaking in. I am not too worried about the tree trunk rotting out, I think the tree trunk will probably out last my DIY build! I have storage heater bricks for the oven floor and reclaimed house bricks for the dome. But too be honest I am contemplating just investing in fire bricks for the whole thing. I would hate to go to all this effort, only to end up with flaky bits of red brick as a pizza topping! The tree trunk turned out not to be level after I spend a long time levelling my hole, hence the concrete on top to make it level. I could have went at it with the chainsaw but didnt want to mess that up and make it shorter and worse so went for this option instead. Another moisture barrier certainly won't harm! My next task will be to make a concrete 'disc' that will sit on top of the tree trunk. This will be about 5 inches thick (re-enforced with bar) and be the exact size of the finished oven. Im either going to go for a 36 or 42 internal, maybe even a 38 or 40? The tree trunk is roughly 1m in diameter, so my concrete disc should not over hang that much if I go with a 36". The main over hang will be the oven landing but I think this will be ok. I have used a concrete calculator and I think I need roughly 350kg of concrete for my disc. A few questions if any one had advice would be great! - Should I buy ready mixed bags (13 25kg bags in total i think) of concrete for my disc, or buy bulk dumpy bags of sand and aggregate and mix it my self? I was worried there would be a lot of waste from dumpy bags, or could I use the left over for my home brew?
- What would the finished diameter (in total inc ceramic blanket and render) of my oven be? I will need this to make my disc as really don't want any space left on my disc when my oven is finished, I want the finished oven to be flush with my disc.
Many thanks for any input in advance! Khylen
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Post by chas on Apr 26, 2017 7:43:48 GMT
Hi All - Should I buy ready mixed bags (13 25kg bags in total i think) of concrete for my disc, or buy bulk dumpy bags of sand and aggregate and mix it my self? I was worried there would be a lot of waste from dumpy bags, or could I use the left over for my home brew?
- What would the finished diameter (in total inc ceramic blanket and render) of my oven be? I will need this to make my disc as really don't want any space left on my disc when my oven is finished, I want the finished oven to be flush with my disc.
Many thanks for any input in advance! Khylen Hi and welcome Khylen. Nice backdrop, heroic timber! Last time I bought some, you broke even on bagged ballast (sand and stones) at 10x ie after 10 you might as well have bought big bag. Factor in 'ready mix' cement content v a couple of bags of OPC and, even though there will be some left over, the bulk bag may be better value. Nothing with cement in it will be much use above the disc of concrete, and neither will anything with stones in it - so don't reckon on using surplus ready mix there - you'll be into soft sand and perhaps lime mortar putty for the oven build. If you arrange bricks lengthways to form your initial circle, and if you plan on using half-bricks for the dome, then the surplus 'ledge' outside easily accommodates the insulation and render finish. So, add 2x 9" to your chosen internal dia. to get the external. You'll be having a slightly unconventional doorway within the circumference, and encounter a more challenging chimney build, but it's doable and the finished product well worth the effort. Keep us posted! Chas
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Post by khylen on Apr 27, 2017 15:16:00 GMT
Thanks for the info Chas it's much appreciated!
I've just ordered a dumpy bag of ballast. Think your right and better to have a bit too much than not enough, especially if it saves me a bit of cash! Hopefully it will turn up tomorrow so I can start over the weekend.
Great idea for laying the bricks flat, if I do go for a 42" internal, that would take my disc to 60" diameter? I think that is doable.
When casting my disc, I hope to try and factor in an oven landing to it also. This will then make it a lot easier to build my chimney etc, just like a 'normal' build as such.
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Post by khylen on May 9, 2017 21:04:27 GMT
Started template for my concrete disc to sit on top of my tree trunk. Will reinforce with bar as there will be a fair over hang when the disc sits on the tree trunk. Ive given myself 9" around the internal oven diameter. This should hopefully be enough for 50mm ceramic blanket and then vermiculite and render. Do you think my oven landing is big enough, or too big even? The oven opening is 19" wide.
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Post by oblertone on May 10, 2017 8:33:01 GMT
Your opening is about 50% of your internal width and so should be fine; as to the landing area, is it big enough to support a flue outside the dome, if so it'll work.
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Post by khylen on May 23, 2017 21:21:12 GMT
Made concrete disc for the top of my tree trunk at the weekend. Went for a 5-1 ballast cement mix, re-enforced with bar, 6" deep. Ended up sizing down and have went for a 36 internal as I was a bit worried about the overhang of the disc from the tree trunk. Going to give it a few weeks before moving it on top of the tree trunk just to ensure it is at full strength.
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Post by khylen on Jul 30, 2017 6:13:29 GMT
Finally got the concrete disc ontop of the tree trunk. At first I wasn't too pleased as the concrete disc does dwarf the tree trunk but I'm sure it will look the part in the end. There is a fair over hang on the concrete disc but I'm fairly confident it should hold...?? The concrete disc is unfortunately not level. I'm in 2 minds weather to take the disc of go at the trunk again with the chainsaw, or lift the disc up and wedge the disc, or just use a grog or cement mix to level the silicate board the whole dome will rest on? Thanks, khylen.
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Post by chas on Jul 30, 2017 7:43:58 GMT
Finally got the concrete disc ontop of the tree trunk. At first I wasn't too pleased as the concrete disc does dwarf the tree trunk but I'm sure it will look the part in the end. There is a fair over hang on the concrete disc but I'm fairly confident it should hold...?? The concrete disc is unfortunately not level. I'm in 2 minds weather to take the disc of go at the trunk again with the chainsaw, or lift the disc up and wedge the disc, or just use a grog or cement mix to level the silicate board the whole dome will rest on? Thanks, khylen. Khylen, this continues to be one of the hero builds. Relax. You're displaying early signs of the anxiety that strikes many builders here. So what if it's not level. By the time there's a dome on there - and you'll be able to compensate during the building of that - no one will care, or know. Time to repost the old ultimate "you think you've got problems" image, reassuring to us all:
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Post by downunderdave on Jul 30, 2017 12:46:14 GMT
Khylen, do you have insulation between the concrete slab and the first course of dome bricks? Secondly it appears that you won't have room for dome insulation and outer shell. You may want to consider making the oven a smaller diameter to enable you to accomodate this.
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Post by khylen on Jul 30, 2017 15:26:14 GMT
Love the picture Chas and I'm sure your right! I think I may just level the silicate board that the whole oven will rest on and as long as that's level then I think I will be fine! As you say, once there is a huge dome on there it will no doubt not matter!
Thanks DownunderDave, I appreciate the advice. The bricks in the picture are just ones I have placed there to see how it looks, I couldn't resist! I bought 200 old red bricks but I'm now not going to use them and I'm going to splash out on some fire bricks to use instead. I will be using calcium cilicate board, 50mm, to sit the whole oven on. From what I've read it should take the whole weight of the oven and I can build the whole thing straight ontop of it, if I have understood that correctly? I thought 50mm would be better than 25mm as it is on a wooden base!
The internal width of the oven will be 36". In the picture it is 36" and I hope to just use half bricks for the first course and all courses, giving me half a bricks room, or 4", for ceramic blanket, vermiculite and render, if I have worked that out correctly?
Many thanks, Khylen.
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Post by simonh on Jul 30, 2017 19:46:24 GMT
This looks like a very cool build
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Post by oblertone on Jul 31, 2017 8:09:47 GMT
Halfbricks are definitely the way forward; and for what it's worth, my reclaimed 200yr old bricks are still doing sterling service three years down the line.
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Post by khylen on Aug 3, 2017 10:24:23 GMT
Half bricks it is! I've been thinking and I will actually use my red bricks for the outside arch, vent and chimney, as this will all be exposed to the elements. I will not have enough room for a second layer of face bricks to cover, if I was to use fire bricks for these, so that should save me a few bricks!
I'm going to make my kilnlinings order in the next few weeks (once I'm back from Bali, where I'm currently writing this, whilst sat in a hammock on the beach, beer in hand, with only wood fired ovens on my brain!!). As I'm only using fire bricks for the oven floor, dome and inner arch, how many do you think will suffice? I know FB recommends 120 for the dome and 60 for the floor (36" internal). I've read many a build thread and read that some have used only 150, inc using them for the vent and both arches. I don't want to under order but like wise don't want to over order!
I will also probably go with either 65mm or 75mm Calcil board. I have read 50mm will suffice: but as it's one of the things that can't be changed later; I'm using a wooden base; I have not used any vermiculite or thermal blocks in my concrete disc; and one of my biggest hopes is that I can use the oven to slow cook on a Monday night after a Saturday night firing, then I'm thinking the more the better!?!
Thanks, Khylen.
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Post by khylen on Sept 29, 2017 14:24:30 GMT
Bricks ordered, arriving Wednesday from kilinlings! Looks like this is going to be a winter build, best get the gazebo out with some serious anchorage!
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Post by crammy on Oct 2, 2017 9:38:36 GMT
Mine started out as a summer build but, i then split up with the Mrs a couple of months ago and lost major interest in it. Ive sorted my head out now and started working on it again. I had lent my descent gazebo to someone but cant remember who and everyone i have asked says it wasnt them. I got a cheap one from argos to do the job and its useless. i have tied id down, put extra rope on it and held it down with 8-10 bricks in each corner. I have also tied it to a fence post. The trouble with this cheap thing is it hasnt got a roof vent to let trapped air out like my other one. I came home from work and it had taken off, hence adding additional weight
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