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Post by wotavidone on Jun 22, 2014 1:03:58 GMT
Started helping a mate build a 36 inch brick oven in his shed. Steel tank stand with a concrete slab poured on top. Underfloor insulation is Hebel aerated concrete. I think this is the equivalent of the thermalite blocks often used in the UK. Mortar is 4 parts sand, 1 cement, 1.5 lime, 0.5 clay. Bricks are fired clay pavers. As far as fire bricks go, my choices are to steal them from my workplace or pay 4 or 5 dollars each for them. So naturally 9 x 4 x 2 inch pavers, at 75 cents each, look pretty good. We had access to a local supplier's "odds and sods" pile, so we picked through and found some nice looking pavers. About 4 varieties. We applied a little test. When we cut one variety in half, the inside of the cream paver was black and unfired looking. When I heated one of these to 450c on a butane stove then allowed it to cool, it didn't survive a drop from shoulder height onto a pile of waste concrete, it shattered into pieces. The other varieties came through unscathed, striking sparks off the rocks and barely chipping. So we called them good enough and started laying bricks. We bedded the Hebel blocks in a 3:1 sand cement screed and put the first ring of bricks on top with the 4:1:1.5:0.5 We have an arch, a floor bedded on a 3:2 mixture of sand and clay, and 5 rings of bricks. Since we had a mix of colours, we decided to get creative. The row of red brick will be followed by a row of alternating red and cream, then another row of reds. Then back to the creams. 4 days of part time work so far (there's lunch, beers, a little session out in the scrub with his yamaha sports quad, etc. All work and no play, as they say....)
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Post by cobblerdave on Jun 22, 2014 5:08:12 GMT
G'day Mick That's looking pretty good. Wow that arch is a bit thinner than id expect. But being tied into the dome should be quite strong enough. Be interested to see how this turns out. And yes I did see that little 1/4 brick in pic one to keep the mortar bonds from lining up, well done, no one will ever know. Regards Dave
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Post by wotavidone on Jun 22, 2014 8:01:23 GMT
Trust you to spot the skinny arch Dave. Each brick is a half brick with the corner cut off, just like the last two ovens. As well, we are using half bricks on the flat, so we need a little more area to mate up to. I made a few mistakes with the geometry, and my mate is a bit imprecise on the saw. It's got a bit of play in the mechanism. To be honest, I'm less than happy with the keystone. He managed to trim quite a bit more off that one than I was happy with. I'm thinking I might lay a few more courses so it's all bonded together, refit the arch mould, and take that brick out and redo it, with a bit bigger piece. What do you reckon? Love to hear from anyone on the forum with an opinion.
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Post by cobblerdave on Jun 22, 2014 20:16:39 GMT
G'day Mick It's the inner arch and will end up black with smoke anyway. I wouldn't bother myself and your mates cuts will improve in time for the outer arch I'm sure cause that's the one people will see. Regards Dave
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rokdok
WFO Team Player
Posts: 130
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Post by rokdok on Jun 22, 2014 20:27:34 GMT
Good evening Mick. Your arch looks cute its litheness beguiles its strength . As Dave said it's neither a structural problem nor an aesthetic one- it's going to be hidden by the external arch anyway. It would be a crime to waste good drinking time in taking it apart and rebuilding it. Cheers RokDok
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Post by wotavidone on Jun 22, 2014 23:01:02 GMT
Thanks chaps. Up close it looks fine, it's only the strength that bothers me. If you reckon the strength is not an issue, I will carry on. I am going to make a big effort to ensure there is a full running bond in that area, to the extent that, if the arch was not there the dome bricks would not fall down anyway.
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Post by wotavidone on Jun 23, 2014 12:06:04 GMT
Day 5 - took myself and the wife to the doctor's in the morning and made it to my mate's place just after midday. My mate is a tidy operator, when I got there, Saturday's work had all been trimmed, pointed, wiped over, etc. Tools were cleaned, floor swept, spillage cleaned out of the oven, etc. Got about 2.5 rings done. Had the usual hassles avoiding the dreaded tear drop where the dome meets the arch. I think we have it OK. Reckon the row with the alternating colours looks alright.
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Post by cannyfradock on Jun 23, 2014 14:07:51 GMT
Hello WTA
What a fascinating build!!.....I really like the way you have formed your inner arch. I've built quite a few Pompeii's but have always used a dome former. I must try using a central pivitol jig on my next build as I only ever guess the cuts to the back of my inner arch.....they always work but it sometimes takes a bit extra effort and the use of 1 and 2" bricks to bring the dome rings back to a 3" brick layer. Using a jig also affords you the time to clean the interior. (I normally remove the dome formers the same day....as soon as the first full ring is made over the transition, but on my last build I had to do it the day after and it was really difficult cleaning and pointing that area.)
Interesting choice of differing colours on the dome structure. You Will of course see these when the dome/oven is fully fired as one of my favourite parts of the build is to fully fire the oven and watch the descending line of soot slowly disappear down from the top of the dome .....leaving the interior soot free.
Great build.......Please keep the comments and pics-a-comin.
Terry
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Post by wotavidone on Jun 25, 2014 10:46:57 GMT
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Post by wotavidone on Jun 28, 2014 4:29:30 GMT
Day 7 progress photos Another couple of courses done.
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Post by wotavidone on Jun 28, 2014 4:44:08 GMT
Day 8. Crushed and sieved some more clay in the morning and went to the builders supply yard and got some more bricks (clay pavers). Made it out to my mate's place just before lunch and we put the last three courses and the keystone in. Cleaned it all up and took some photos. Unfortunately the light is nearly gone by 5 pm in June, so all the photos have been under flood light and I'm only using a camera phone so the quality is not the best. But here it is, closed dome. Of course, looking through the photos, I don't have one with the keystone in place. Ah well, I'm going back to build the outer arch and the flue, etc., so I'll get some then. Poor mate is torn - he loves the look of the outside of the dome and he'd love to leave the bricks so he can see them, but he also gets the whole insulation thing. Decisions, decisions. I suppose, if I was a real glutton for punishment, I could show him a picture or two of cobblerdave's oven. That genius built his whole insulated igloo, then went back and created an outer dome of brick, so his has all exposed bricks on the outside. It looks amazing, looks like an ordinary brick dome, but has a whole layer of insulation hidden between the two brick shells. Just search for cobblerdave's build on the Forno Bravo forum.
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Post by cobblerdave on Jun 28, 2014 6:41:01 GMT
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Post by cobblerdave on Jun 28, 2014 7:14:38 GMT
G'day again Mick The reason for bricking over my igloo was not just I like the look, it was also for the waterproofing. Is a big mass that takes the water a long time to soak through and its not going to crack like a thin cement render shell. I always had a crack behind the chimney which was silasticed. From you pics you have 150 mm (6 in) from the dome to the edge. 100mm (4in)of pearcrete insulation then use the pavers on there edge 50 mm (2in)..... perfect!. To get the pavers looking neat score a neat line with a diamond blade on an angle grinder then snape with the brick bulster. Gives you a new use for those rejected pavers than being budgie poo collectors..... When you tell people that you have a brick wood fired oven you really have a brick oven.
Regards Dave
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Post by wotavidone on Jun 29, 2014 3:54:15 GMT
It's a good thing my mate has resisted learning about the internet all these years Dave, or he'd be reading this and getting ideas. We left enough room for 4 inches of perlite and a layer of render, and I guess we could stretch it to a 50 mm thin brick shell, but I dunno if I'm willing to do that much work. I'm just pleased it's all looking OK at present. Looks like the arch is solid enough for holding up the bit of dome that bears on it. Latest problem is laying hands on some flue work. Local heating suppliers generally only carry 6 inch. 9 inch can be obtained - for $100 per length ordered in. I'm hoping we can obtain some 6 inch cheap and do a "double barrel" design.
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Post by wotavidone on Jul 7, 2014 12:25:20 GMT
After building an outer arch, we had a few days off from the oven while my mate obtained a couple lengths of 8 inch single wall flue. He also got our builder mate (owner of the brick saw) to knock up a stainless steel plenum chamber/adaptor box, to mate the 12 inch by 5 inch opening in the bricks to the 8 inch round flue. As welders go, he makes a very good carpenter. However, the adaptor is functional, and after a clean up with a sanding disk in the angle grinder actually looks OK, we think. I was happy, as I was assuming I'd have to make the transition with bricks - not something I was looking forward to. The outer arch was made with old red bricks - a nod to my mate's desire for a certain level of "rusticness". Until we laid them last week, these bricks were doing duty as "pavers" - had to clean the moss off before we laid them. They were so saturated that nearly a week later they are still wet. The other thing was, no two of these third hand bricks were the same size! It's amazing how easy "rustic" was to achieve under those circumstances. I didn't mind, the bricks are old and third-hand but they will probably work. In any case, it's the outer arch. If it doesn't work out, it's any easy fix. The arch is a fair bit bigger radius than the inner arch. This is because a previous mate reckons that's one thing he'd do different if he built another - he only made his outer arch, which is one and a half bricks deep, an inch wider than the inner arch, and he reckons it restricts him a bit when he's loading the oven. So we made sure this arch, which is about one and a quarter bricks deep, wider so that it's easier to feed the oven from an angle. The oven is now in usable condition. He wants to dry it out and use it before we insulate over the dome. I don't think it'll do any harm. The mortar has set like a rock and has absolutely no shrinkage cracks visible. Over a week since the dome was completed, the inner surface of the dome is covered in condensation every morning. I think this is good - keeping the mortar damp for a couple weeks should ensure the lime carbonates well before the oven is fired. Total time is 11 part days to get from an empty stand to an oven with a flue. My mate's happy, and I'm convinced I'm never working on another oven.
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