phi1
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Post by phi1 on Dec 4, 2014 14:39:27 GMT
This is my exploratory excavation into my rockery. (can't believe how much spoil this small excavation produced) It looks positive as it is a solid chalk base (South Downs) I hope to salvage the shrubs and then open up to about 1.5 m square and cast a concrete base with rebar inside to about 100mm thick. Can't see much being done before Christmas as it hasn't stopped raining and I have some family commitments
I will post as I progress
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phi1
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Post by phi1 on Feb 13, 2015 13:57:50 GMT
I have a sliding mitre saw with a 250mm blade with a 30mm spinal hole tipped wood blade. The only blade that might cut fire bricks or other bricks for the dome is Bosch Professional for Ceramic Diamond Tile Saw Angle Grinder Blade. All other suitable blades i.e. masonry blades have a smaller spindle hole (25mm ish) it costs about £25 which seems reasonable I spoke to the supplier who said it would be ok but might wear out quickly, as it is a one off project that will be fine. Any comments or help from the forum before I buy the blade? Thanks
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phi1
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Post by phi1 on Feb 13, 2015 14:04:47 GMT
I have now dug a bit more chalk out to accommodate a 1.5m square base.
Shuttering in place with some old re bar, hope to borrow a concrete mixer next week to cast the base.
Next stage is to source thermalite blocks and start cutting firebricks for the base of the oven. I got some surplus firebricks for the base from a member of the forum at 50% less than from a building merchant :-)
Will post photos of next stage in March as we are going away from the cold for a couple of weeks.
I will check the buy/sell thread when I get back otherwise it's off to Jewsons - Do we still get a discount there? Anybody know the current A/C number?
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Post by cannyfradock on Feb 15, 2015 14:08:43 GMT
Hello Phil......welcome to the forum. I recently (ish) built an oven in a similar location to yours ukwoodfiredovenforum.proboards.com/thread/1230/pompeii-build-abersychan-wales (on a bank) so I'll try to answer a few of your questions and pass on a few tips. Because the oven will be built on solid ground I made sure that there was a polythene membrane under AND around the base of the oven. I was lucky enough to have natural stone at hand to clad the oven but I believe the oven itself will be quite similar....90CM interior.If you haven't put membrane under the concrete, then you can still put it under the insulation layer. Many members have used cheap masonry blades (including me) for cutting their fire-bricks.....the main thing is to soak the fire-bricks before hand. If you only intend using the fire-bricks bought from the member on the hearth only, then the next best thing to fire-bricks for the dome is storage heater fire-bricks which pop up quite often...and cheap on E-Bay. Don't forget that they are very heavy so calculate the weight before travelling to collect. Next best thing that I know is the old imperial red clay bricks which are often seen on Victorian/Edwardian properties and can be often found in skips. Members have also used class B engineering bricks. Not sure on the Jewson account as I've been away from the forum for a while. One of our members was trying to get a better deal for us but I'm not sure how that's going. The account number is WOOP 248. The account is still live. Best bet is to ask at your local Jewsons for a printed quote on what you want (quoting the A/C number) and see what you can get. All the best with your build... Terry
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phi1
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Post by phi1 on Feb 16, 2015 10:07:12 GMT
Terry Thank you for you advice. Really useful advice about the membrane, I will dismantle the shuttering and put a membrane in place. (I was hoping to pour the base this week and leave while I am away for a couple of weeks). I got 70 fire bricks at the moment which I was going to use on the base over thermalite blocks. In an ideal world I would like to build the dome with firebricks otherwise I will use old clay bricks. Re the saw, I would like to angle cut each brick to accommodate the dome so they fit together nicely, Its not just my OCD I think it will improve the thermal insulation. Phil
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rokdok
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Post by rokdok on Feb 16, 2015 21:43:41 GMT
Hi Phil, Good luck with the build. I'm sure the blade you've got will be fine. I used an evolution mitre saw and checked the spindle diameter and you're right - it was 25.4 mm. Main thing is that it is a diamond blade. Soak your bricks well before cutting - it not only cuts down the dust but also reduces markedly the wear on the blade. Best Wishes, Paul
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Post by cobblerdave on Feb 17, 2015 5:25:22 GMT
G'day phil One thing you'll find cutting with a diamond blade, dry particularly, is that the edge will glaze up. You'll think it blunt but it's not. To deglaze and bring fresh diamond to the cutting surface all you have to do it to cut into something hard. A piece of hard rock or a piece of concrete will do. Regards dave
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Post by kstronach on Feb 17, 2015 12:48:44 GMT
Cutting in to sandstone is the best thing to bring your blade back. Good luck with your build
Keith
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Post by cannyfradock on Feb 17, 2015 17:29:50 GMT
Phil
The forum (s) have been going since 2009 and many people over this time have used the old reclaimed clay reds for the dome and all have said that they work well with no spalling (brick face spitting and flaking). You sound like you have enough fire-bricks for the hearth and the first ring course. That sounds perfect as all your hearth will have the "massed" heat needed to make the oven work efficiently. Clay bricks on top of this will work fine.
I admire you for wanting to take the time to cut the dome bricks....or trapazoid cuts as they are known. I've built about a dozen brick Pompeii ovens and quite a few more in Clay but I've always been lazy and used half bricks cut with a hammer and bolster,(typical lazy bricky) only using the angle grinder to cut the top corner off the back of the internal arch to make the dome arch transition a little easier. I also cut the halves in half and... then quarters for the final few courses of the dome.
If you stay in the ball park "rules" of Pompeii oven building i.e....dome height = half the diameter and the internal arch height 63% of the dome height, then you will have an oven that performs to it's full potential.
Terry
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phi1
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Post by phi1 on Mar 7, 2015 9:19:01 GMT
Sand base and membrane now in place (thanks Terry)
Re assembling the shuttering today, if weather holds will cast the slab tomorrow.
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phi1
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Post by phi1 on Mar 8, 2015 16:55:36 GMT
Cast the base this weekend. DIY and a new skill for me, first couple of mixes (ballast 6:1) too wet but got it sorted. Filled the shuttering, used all the ballast I had ordered and left with 300mm x 500mm x 100mm deep unfilled area at the back, off to Wicks this morning couple of extra bags of ballast job done, mixer cleaned, patio washed down. It looks ok even though the hole was filled in after 12 hours I have covered the base with a tarp as rain is forecast for tonight, will remove the shuttering next weekend and post a photograph. Next planned stage is to put a layer of thermo blocks or celcon blocks as an insulating layer, any observations or comments? Off for a hot bath and Radox now, not as fit as I thought
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phi1
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Post by phi1 on Mar 15, 2015 18:34:13 GMT
Base sorted and have started to cut the firebricks for the base of the oven Decided to use reclaimed clay bricks for the dome rather than fire bricks mainly due to cost. I am really confused about what mortar to use Fire cement seems ideal providing the joints are fairly even and generally less than 5mm. From most photos I have looked at the joints are a V rather than cut every brick on 4 sides. Next choice seems to be builders sand, portland cement, lime and fire clay Then there is the same as above but using fire brick grog. Any clarification would be greatly appreciated as I would like to plan one specialist order due to the high delivery costs as there are no agents within reasonable distance in East Sussex where I can collect materials. Thanks Phil
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Post by cobblerdave on Mar 15, 2015 21:38:20 GMT
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Post by chas on Mar 15, 2015 22:00:38 GMT
Phil, Travis Perkins stock lime putty in tubs. Mixed at about 1 part putty to 1.5 sand, it's an easy mix, easy use, classic mortar well suited to soft reds. It doesn't set 'hard' hard - but as the acres of Victorian brickwork on display testifies, it makes walls with soft reds, and appears to stand up to the heat pretty well. You don't need a mortar that's harder than the bricks its cementing. My dome's stuck together with potters clay, which isn't exactly hard either... had you considered clay? It's easier to use and requires no former for the dome while in progress - you stick the bricks (or half bricks more like) together with the clay. Magical.
Chas
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phi1
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Post by phi1 on Mar 16, 2015 9:26:04 GMT
Thanks Dave and Chas Your advice helps as always I used to be indecisive but now I'm not sure
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