Oven on wheels

[wotavidone]

Re: Oven on wheels

The two arch bricks are 400 apart, a bit less than 4 bricks wide, and I was going to cut the two outer ones to slide in. Just discovered the brick won't fit in my saw for the long cut, so I just cut two bricks off and laid em crossways in clay. They come just to the front of the arch bricks. Its all tarped up now, so I can't quickly take a photo, but they will be captured by two ordinary bricks mortared with the real stuff later. Its testing me!!
It should all work out eventually, I suppose if it was easy, anyone could do it.
That clay is surprisingly good at holding stuff where you put it though.
The vermicrete came up as rough as rough, but a 1/4 inch skim of clay sorted it out. Any biggish holes just filled with clay.
I'm not even that concerned about it getting wet once its done. I think it'd pretty much have to fill the floor up first, which is quite a bit of water.

[cobblerdave]

Re: Oven on wheels

Gudday
sorry for flogginfg the same horse ......trap the brick in front otherwise heat will expand you hearth bricks the resulting gapes will pack down with ash in the end moving the front out....? Regardless how tight your saw cuts ..contain the hearth is what I would aim for.

Regard dave

[david s]

Re: Oven on wheels

"I can see what they say about drying the floor. There must be a gallon or two of water in there"

That's about right. For every 20 litres of vermiculite it will take around 6 litres of water. Just ask yourself how long it would take to boil dry a container of 6 litres of water. Now that you have covered it the weather won't do much to dry it, so expect your drying out to be slow.

[wotavidone]

Re: Oven on wheels

Gudday
sorry for flogginfg the same horse ......trap the brick in front otherwise heat will expand you hearth bricks the resulting gapes will pack down with ash in the end moving the front out....? Regardless how tight your saw cuts ..contain the hearth is what I would aim for.

Regard dave

Trust me, it will be done!

they will be captured by two ordinary bricks mortared with the real stuff later.

[wotavidone]

Re: Oven on wheels

Got an arch now. Seems to stand up by itself OK. I've covered it wit a damp sheet, and giving it a day to set up properly.

[wotavidone]

Re: Oven on wheels

Got the first ring of bricks on now. Unfortunately it was dark o'clock when I got home from work, so photos aren't as good as I'd like.

[cobblerdave]

Re: Oven on wheels

Gudday
Looking Good....like the angle on the first two chains thats different!

Regards Dave

[wotavidone]

Re: Oven on wheels

Different?
I suppose it looks like its curving over quick, but I guess thats because the first lot are full bricks standing vertical. I'm only looking at 375 mm internal height, and that first chain rises about 100mm above the floor already. Its all because I can never make a decision and stick to it. I was going to just have that first vertical ring of brick, then mould a dome from the home brew mortar. But then I decided to keep going in brick.
I do worry about the stability of two inch thick bricks mortared edge to edge. All very good while its all stuck together with nice unmolested mortar, what happens after the big scarey fire has weakened the mortar?
I just read the posts of the guy who built the geodesic dome, and he reckons he wouldn't go that thin (2 inches) again. Still, he had gazillions of joints.
I believe I will add an inch of mortar render over the outside of the dome for mass and stability. And I still have a bit of time to ponder the wisdom of that layer having some reo in it.

[cobblerdave]

Re: Oven on wheels

Gudday
What did you settle on as your mortar mix?...and whilst I'm asking, what is the mix for the dome proper?

Regards Dave

[wotavidone]

Re: Oven on wheels

Good day Dave
The mortar is the homebrew- 3 sand, 1 clay, 1 portland cement and 1 hydrated lime.
Its very funny stuff to work with, very quick early grab, but quite delicate for the next few days. After a week it's like a rock.
I have been religiously keeping it damp until I get full strength from the portland cement. I have a theory that this will minimise cracking from clay shrinkage.
In the first ring, the vertical bricks, I had a few "moments". When I finally closed the ring with a trimmed brick at the back, I didn't trim quite enough, and when trying to tap the brick in I dislodged a previous section. It came out as two bricks stuck together - sorta like an opened book. I mortared it back in the same with the trwo bricks still joined together. So it is fairly strong. One other joint in that bottom ring gave me trouble. I don't know why, but the mortar simply did not stick to the brick on one side. So I chiseled that one out and grouted it back up with ordinary mortar - 3 sand, 1 portland cement, 1 lime. That one has no evidence of cracking whatsoever now.
Of course it might behave different when heated. I look on that one as a sort of performance trial.
By the way the clay is ordinary clay, not high alumina "fire clay"
I have local oven builders telling me I don't need any, here on the forum it has to be "fire clay" though some people seem confused as to whether that fire clay should be fired or unfired when it goes into the mortar, and a local bloke who grew up making bricks for a living with his father telling me that ordinary red bricks and ordinary mortar with PC and Lime didn't fall to bits when they built brick kilns out of it, so why would it do so in a pizza oven?

[wotavidone]

Re: Oven on wheels

P.S. unless I run into serious difficulties, the dome will be all brick.
I'm turning into a klutz on this job though. I've been working after dark a bit. I have been, for me at least, quite diligent about having a cleanup when I down tools for the evening. I'm not working in a massive wide open space, and the last thing I need is to trip on a brick offcut or something.
And its easier to a good job when the tools are clean and easy to find and there is no old mortar and chips of lying about, etc.
To get the height to work comfortably I have been standing on a ply wood box that is very sturdy and has quite an area, so it's pretty safe. The other night, I tripped over that box while cleaning up so that I wouldn't trip over anything.

The pain in my shin where I raked it down the edge of the box was excruciating. I was rolling around on the lawn clutching my leg and "cussin' up a storm" as they say. It hasn't completely gone away yet, and my leg keeps swelling up over the top of my work sock.
To add insult to injury, as I went arse over tit, I put my hand through the 4 bricks I'd just finished laying 10 minutes before the accident/stupidity, and had to relay them the next night.

[wotavidone]

Re: Oven on wheels

I have finally got another course of bricks done. I relaid these several times. Around the back, I ended up with very poor joins, and a mismatch of sizes and angles. So I recut 4 bricks and did that again. At the front, where the ring joins the arch I got a bit of the teardrop happening.
I knew that I could bridge the two gaps either side of the peak of the arch with mortar when I laid the next chain, but I felt the gap would be too big.
After much puzzling and trying different things, I decided the best thing to do would be to lay two small wedge shaped pieces to bring it all back to near enough to round for the next chain to lay on.
So, inelegant as it is, I'm ready to lay the next chain. I just have to rustle up the enthusiasm.
I took time out to drive down the coast yesterday. Took the youngest boy with me, and we made a full day of it, visiting a farm museum, taking the dirt tracks home, exploring a couple out of the way towns, especially their pubs , thank goodness for light beer, etc. Turned a bitumen road 220 km round trip into at least 300 km. I was trying to show him that there are way more interesting things in the world than video games and lap-tops.
I think it worked, but I'm kinda flat today.

[cobblerdave]

Re: Oven on wheels

Gudday
Its looking better and better the clay pavers work well it should give you a fast heating oven to.
Dont worry about the "repair pieces" to fix the teardrop effect......no one will ever see them....unless you would be willing to get on your back and slide you head into the oven it would never be seen. I've a 42in and most people are pushing to get a good enough angle to see the top of the inside of the dome when you try to discribe the keystone at the top of the dome.

Regards Dave

[wotavidone]

Re: Oven on wheels

Thanks for the encouragement Dave. So you don't think it'll fall down then?

[cobblerdave]

Re: Oven on wheels

Gudday Mick
I'm a simple man and I like things simple....your have a dome under construction there and a dome is strong because of gravity thats why it resists falling down so well. If you neeed any encouragement go back and have a look at some of those old roman ovens photos which survived a few thousand years.
Anyway you have passed the entrance height now and thats the hard bit I recon so now put up a sand mold cut you paves smaller and the keystone will be in before you know it

Regards Dave