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Post by martyn on Jan 19, 2021 14:21:55 GMT -8
I have almost finished this large wood fired oven, I was lucky to have a nice budget for this one!
100mm of ceramic fibre board under the oven and 900lts of vermiculite surrounding the dome.
Once up to temperature it takes four day to return to ambient temperature .
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Post by josephcrawley on Jan 19, 2021 16:32:35 GMT -8
That's a very very nice looking oven!
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Post by Dan (Upstate NY, USA) on Jan 19, 2021 19:01:18 GMT -8
I was a mason's assistant to my grandfather as a 15 year old. He has since passed away but he would be tickled pink with the structural details of this build.
Should outlast us all if it is a non freezing climate...
You get a date & signature in there somewhere?
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fuegos
Full Member
not out of the woods yet
Posts: 177
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Post by fuegos on Jan 20, 2021 7:57:16 GMT -8
Nice work Martyn , it's good to see a round build , less monolithic. Is that your stonework to the right of the oven , the wall ? Did you use lime mortar ?
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Post by martyn on Jan 20, 2021 9:23:21 GMT -8
Yes lime mortar for the granite work and lime with a little cement added for the brick work.
I still have to do the lime cement capping on the roof.
The wall is freshly built but not by me.
i made the doors from an old oak bed, i think it was at least one hundred years old and it did not like the outside moisture!
i had to rebuild them but they seem stable at the moment.
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fuegos
Full Member
not out of the woods yet
Posts: 177
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Post by fuegos on Jan 21, 2021 3:01:31 GMT -8
" lime with a little cement added for the brick work" interesting .I've used a bit of lime in a cement mortar as a plasticizer but not the other way round .What's the idea behind that ? Does it help the lime cure ?
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Post by martyn on Jan 21, 2021 7:03:54 GMT -8
Yes one part lime one part cement for four parts course sand for brick work, it drys a lot faster than plain lime and the cement also makes it set a lot harder.
When I build brick arches or any form of decorative brickwork I like to sand it with a diamond sanding blade in a 4’’ grinder, round the edges and form a nice radius but with plain lime mortar, it is not strong enough to hold the coarse grit in place and it just wont sand smooth.
The cement is just enough to hold the grains in place after about a week, the lime on its own would take months to get hard enough if ever!
I dont want the mortar to look too different from the stone work mortar, that is mixed one part lime two parts course sand.
When I made the round chimney i used one cement one lime four fine sand with two parts water one part PVA.... that makes a very strong morta!
I make my own domes as well... or at least I have been doing so for many years but my mold finely gave in as is no more!
So I had to buy the dome for this oven build, it is no where near as good as the ones I made ... so my next project is to build a new mold...
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fuegos
Full Member
not out of the woods yet
Posts: 177
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Post by fuegos on Jan 21, 2021 11:22:14 GMT -8
great stuff Martyn , thanks for the tips .Lime mortar is tricky here in this part of Spain - temperatures in the high 20s from as early mid march & we can have frost from mid octubre to early march.....I Did a 3:1 render on my oven build & it's cured pretty well apart from 3 expansion joints (cracks) o think this is due more to the fact that i didn't build a proper double skin .What do you make the moulds from ? ply ?
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Post by martyn on Jan 21, 2021 13:25:39 GMT -8
No I made the mold from foam fibreglass, it was a time consuming and labour intensive job, that one lasted for around 20 cast over the last five years.
The main problem is that refectory cement sticks like you know what and I had to force the components apart several times and they eventually got too worn out !
I could repair it (again) but I feel I could make a better one .....
Basically I made a form for ridged foam in the shape of a finished dome and then fiberglased over the foam.
Then I hacked out all the foam and spent weeks sanding the inside then cutting it into sections ....it took many weeks of work!
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fuegos
Full Member
not out of the woods yet
Posts: 177
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Post by fuegos on Jan 22, 2021 2:25:09 GMT -8
On concrete pours we used a mineral oil based product with "plastic" covered shuttering ply but eventually the smooth surface becomes abraded & the concrete sticks like something to a blanket.... Diesel was also an old school favourite and a quarter of the price of the fancy Sika stuff. How about lining the mold with paper or aluminium foil ?
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Post by martyn on Jan 22, 2021 7:28:07 GMT -8
Refactory cement seems to stick to anything, far more so than ordinary cement but yes perhaps lining it with something would work. Thanks for showing an interest ....  |
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Post by pigbuttons on Jan 29, 2021 5:05:16 GMT -8
Late to the conversation here but want to share a little. Aluminum foil is a bad idea as it reacts with the chemicals in almost everything with cementisious ingredients. If there is a chemical reaction going on Aluminum wants in on it.
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Post by pigbuttons on Jan 29, 2021 5:11:28 GMT -8
No I made the mold from foam fibreglass, it was a time consuming and labour intensive job, that one lasted for around 20 cast over the last five years. The main problem is that refectory cement sticks like you know what and I had to force the components apart several times and they eventually got too worn out ! I could repair it (again) but I feel I could make a better one ..... Basically I made a form for ridged foam in the shape of a finished dome and then fiberglased over the foam. Then I hacked out all the foam and spent weeks sanding the inside then cutting it into sections ....it took many weeks of work! Not my area of wide knowledge but How about one of those big exercise balls as a mould for the fiberglass. Cut a hole in a sheet of plywood large enough for the ball to protrude to the size you want and use a ratchet strap or two crosswise to hold it in place. Coat the exposed ball with paste wax or shoe polish, lay the fiberglass mat down and tape it to the plywood. Add resin to suit. When cured you just let he air out of the ball and you should be good to go. |
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Post by martyn on Jan 29, 2021 7:53:44 GMT -8
Hi pigbuttons, thanks for your interest.
That would be a good starting point but the mould is actually a very complex thing as it uses mutable take apart components that all have to fit and lock together so that the ovens are actually formed in components.
A one piece oven would just crack on the first burn and be to heavy to move, even the interlocking components have to have 5mm clearances around all the edges.
There are a couple of issue with the ball method one is they are not actually consistently round and they are covered in dimples but many people use them for casting smaller DIY ovens.
The truth is I am semi retired now and I am concentrating on other aspects of life so I probably won’t build another mold.
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