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Post by oblertone on Nov 19, 2016 7:11:56 GMT
Well that's not going anywhere is it ! Excellent start, keep up the commentary in the spring.
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Post by chas on Nov 19, 2016 9:07:44 GMT
So, finally finished the rendering, ended up being a little 'rustic' in places - I've learned (too late) that adding softsand to the render mix can help with a smooth finish and masonary filler (bit like wood putty, but for concrete) is good stuff and can fill in uneven patches. Am now downing tools for the worst of winter with the plan to build the clay oven in late Feb / March. You say 'rustic' we say 'Artisan'. Well done, keep us posted! Chas
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Post by dave36 on Dec 25, 2016 20:46:24 GMT
Santa Claus brought me some bricks and a circular saw to cut them with... thanks Nixie - have borrowed your hearth design...
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Post by 5leafclover on Dec 30, 2016 12:20:42 GMT
Exciting times!
Keep the pictures coming. Your plinth is looking great.
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Post by dave36 on Jan 4, 2017 8:59:40 GMT
Bricks now cut to size for the hearth. Tough work on the diamond blade, after a bit of trial and mostly error, soaking the bricks for 3-5mins immediately precutting seemed to do the trick (stopped the blade spitting out glowing chunks of itself). BTW - whilst a bit pricey (£100), an evolution rage 3 sliding compound miter saw makes this a lot easier and more accurate (if you look carefully at pic you will be able to spot the bricks bricks split with hammer and bolster) it will just about cut a 64mm deep firebrick and the slide function makes cutting angles relatively easy.
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Post by downunderdave on Jan 4, 2017 10:34:03 GMT
Bricks now cut to size for the hearth. Tough work on the diamond blade, after a bit of trial and mostly error, soaking the bricks for 3-5mins immediately precutting seemed to do the trick (stopped the blade spitting out glowing chunks of itself). BTW - whilst a bit pricey (£100), an evolution rage 3 sliding compound miter saw makes this a lot easier and more accurate (if you look carefully at pic you will be able to spot the bricks bricks split with hammer and bolster) it will just about cut a 64mm deep firebrick and the slide function makes cutting angles relatively easy. While I'm all for adapting tools for purposes for which they were not designed, you need to be aware that a compound saw designed for cutting wood may not be a suitable solution. Brick dust is essentially tiny shards of fired clay which can be extremely hazardous to the silia in your lungs. Do a search on brick dust hazard to learn of the dangers, because it may affect your family and neighbours. Wetting the bricks prior to cutting will reduce the dust but not eliminate it. A purpose built wet brick saw will reduce the dust problem to a minimum, but a decent respirator, not just a dust mask (useless) is wise. Some home builders have arranged water feeds to the blades of their compound saws in an effort to reduce the dust, but unfortunately, as the saws are not designed to be operated with water there is then an electrical safety issue. In addition the cooling intake around the brushes and commutator allows the dust in and can decommission the motor. Where possible use the bolster to cut the bricks in half. It won't matter if the rough end sticks out to the outside because this will be covered by blanket anyway. i'm not saying don't use it, but be aware. Good luck. Dave
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Post by dave36 on Feb 2, 2017 22:52:17 GMT
Bit of an update. Got itchy feet waiting for the weather so bought a gazebo with sides to keep the rain off. Have now cut and fitted the ('solar' grade- better insulation) breeze blocks (see pic) that will sit under the ceramic fibre board...
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Post by dave36 on Feb 2, 2017 23:10:38 GMT
Question for the gurus- have cutted and glued (heat resistant WFO sealant) the 'key stone' to my brick arch door. I also braced with metal strips, then in goes a short chimney piece to which I can insert the actual flue when using the oven (I wanted this two piece design so could take off chimney and cover oven when not in use / over winter). Ceramic fibre blanket wrapped round the short flue length and WFO cement (2cm depth) at top and bottom to stop the blanket being set alight (bottom) and getting wet (top, note top will also get a coat of K-rend). Two photos attached. The exam question - metal expands / contracts more than brick. The metal strips (screwed to the arch bricks) are insulated away from the main heat of the oven (and any flames coming towards the flue) - but - is the distance and insulation enough or do I risk the metal contracting / expanding enough to put stresses on the arch leading to mortar cracking etc. Oven is 80cm diameter, clay build, flue in the right place (just butting the dome, at front). Sorry, bit of a techie question! Am relaxed about taking metal strips out - the sealant is a reasonable glue and if I get the arch right, there should be natural gravitional compression on the keystone, but part of me quite likes the meta strips (I assume I won't quite get a perfect keystone right fit). Thanks!
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Post by downunderdave on Feb 2, 2017 23:46:44 GMT
Nice build. A couple of things, you don't need to worry about setting the blanket alight, it is fireproof, but should be sealed against any fibres coming loose. Steel has much the same expansion rate as concrete and brick, hence its popularity as a reinforcement for structural concrete. The problem is that it is way more conductive than either brick or concrete. This does not pose a problem at ambient temperatures or when the temperature rises or drops relatively slowly under normal weather conditions where both materials will be much the same temperature. For a kiln or oven the temperature rise is very rapid, around 300C/hr. if the steel is facing the fire then it will expand way faster than the surrounding refractory. If embedded in the refractory its expansion will still be more rapid but not as bad. This is why stainless steel needles are used as reinforcement in refractory. The increased surface area allows the refractory surrounding the needles to conduct the heat from them into itself. Steel placed outside the refractory will take longer to heat and therefore expand so this is the best solution if using steel and bricks. It is the usual method for using bracing around kilns Apologies for the long winded answer.
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Post by dave36 on Feb 20, 2017 9:15:03 GMT
Hurray, arch didn't collapse when the wood former was taken out! Onwards to the sand former...
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Post by dave36 on Feb 22, 2017 18:02:56 GMT
It's been a couple of decades since I built a sandcastle...see attached. This bit was (surprisingly) easy, albeit not in the photo, I am checking shape / size with a MDF template to ensure a (near) perfect hemisphere. Tip- fine spray with water every now and again tends to keep the soft sand together in shape.
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Post by dave36 on Feb 27, 2017 9:55:48 GMT
Wow That was a hard day , 10 hours and I had my neighbour helping too. Clay dome done, 80cm diameter, 8cm thick. Used about 70kg of pure terracotta and 140kg of soft sand and a little water. Picture below and a few tips: - I don't see how this could be done in a day with only one person, get some help! - we used a cement mixer, throwing smallish flakes of clay into as it revolved. Worked really well, only needed a 10-15min puddle after the initial mix up. - kebab sticks taped off at 8cm were helpful to check depth as build went on. - little 8x10cm bits of wood were helpful in forming bricks of consistent thickness. - tamp up the dome (slap with hand / wood) helps stop slumping. Tamp as much as your patience allows, helps get the air out. - we finished it off with a float to get a nice smooth surface. Doubt there's any real point in this but it was a rewarding 10mins. Good luck! D
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Post by dave36 on Mar 5, 2017 11:10:34 GMT
A small update. Am now taking out the sander former in 2-3 inch sections, with rows of tea lights to help dry the clay (moving along when inner shell hard). Seems to be working well, one crack on the arch that went all the way through, but now filled (albeit suspect I will be seeing it again when the temperatures pick up). Attached is a slightly pointless but pretty picture,
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Post by downunderdave on Mar 5, 2017 20:32:46 GMT
A small update. Am now taking out the sander former in 2-3 inch sections, with rows of tea lights to help dry the clay (moving along when inner shell hard). Seems to be working well, one crack on the arch that went all the way through, but now filled (albeit suspect I will be seeing it again when the temperatures pick up). Attached is a slightly pointless but pretty picture, Depending on conditions of course, but normally clay takes around one week/ inch of thickness to dry, so be patient.
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Post by dave36 on Mar 6, 2017 8:38:03 GMT
A small update. Am now taking out the sander former in 2-3 inch sections, with rows of tea lights to help dry the clay (moving along when inner shell hard). Seems to be working well, one crack on the arch that went all the way through, but now filled (albeit suspect I will be seeing it again when the temperatures pick up). Attached is a slightly pointless but pretty picture, Depending on conditions of course, but normally clay takes around one week/ inch of thickness to dry, so be patient. Thanks Dave, that's a useful stat to know, looks like I've got at least another couple of fairly dull weeks of tea lights and tiny fires to go...!
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