New 36" Pompeii in Bondi

[cobblerdave]

G'day
Wozza I've gone though a couple of "updates" of forums and this one is no better.
In our time zone they are using the time to upgrade and reset and I bet there fighting the Bots that threaten the site with spam!
On the joints that are threatening to line up.
Start your build at the back and the joints that threaten to line up will start on the sides.
Consider 1/3 and 2/3 bricks rather than 1/2s they seem to work better
Regards dave

[cobblerdave]

G'day again
Lost a full reply so I'm going to do this in bits.
Inverted Vs are too high up in the oven to see when flashed up anywayand
Your dome when complete owes it strength to the contact of the rows of brick rather than the mortars on the sides of the bricks.
Your fighting gravity now but when it's complete the dome has gravity to make it strong. That mortar on the side of the bricks does nothing to make one dome strong it keeps the brick orientated in the correct position only.
Regards dave

[cobblerdave]

G'day
Again I'll battle on.
Mortar. As you build the mortar is the glue that holds the structure up?
But the completed dome it gravity that makes it strong And that mortar now becomes the gasket that keeps the brick units in correct orientation to make the dome strong.
Like I said a gasket, a gasket that has to flex independent of the bricks, the dome units.
The Forno homebrew is a bit strong on the cement bits for light duty fire brick. It a bit better on med to heavy duty and definite a no for chimney bricks or commons.
So it's a bit safer to use 5 parts of sand to the 1-1-1 of those cementious parts
Regards dave

[cobblerdave]

"It's looking good. Can smell those pizzas already. I was going to ask how difficult it was to move around but you've already answered that.

I like the arch as well. Probably because it looks a lot the one that I just made and I was worried about the structural integrity as it was rather 'flat'. But if yours is OK, then it gives me more confidence that min"

G'day Wozza
Seen your comment above. Your oven mouth entrance is not too flat or weak an arch. As it's the entranceway it tied back into the dome and it's a integral part of it, it's strong as.
If you entrance follows the same profile it will still be strong. Most oven entrances are really small structures and don't suffer the same amount of weight and stresses. Theres a lot of other ovens that would have failed if this were a problem.
I Built a big deep entrance. A lot bigger than most and then loaded it up with a brick chimney. In the end I thought it prudent to buttress. Not because its a normal entrance
Your oven like all the others should not have any problems.
Regards dave

[Wozza]

Thanks Dave. Given me some confidence.

The arch already has a very slight 'crack' as in a slight separation between one brick and the mortar between it and the next. I was going to post a piccie but it's too small a detail to actually see. So, WTF, I'll ignore that.

Up to the fifth course and out of bricks. Just at the point where the dome meets the arch. So off to the supplier tomorrow to get everything that I hope I'll need to finish the thing.

Been using Home Brew for the last two courses and quite happy with it. But that lime screws your skin up. I was packing mortar in using my fingertips and they are pretty sore tonight. Looks like I'll have a shitload left as well so I'll have to think of how to get rid of it. Unless it's used in rendering the outside of the dome on top of the insulation.

[cobblerdave]

G'day Wozza
Break out the vinegar from mums pantry and soak your hands in it. It will not repair the damage from the lime and cement burns.
But it will take away the sting and terrible itch!
Regards Dave

[Wozza]

Onwards and upwards to the 5^th course.

I headed west early Monday to pick up the rest of the bricks and the insulation. I think I have everything I now need to finish.

That inverted V one gets on uncut bricks is obviously getting a little larger the higher I go. I have some of the high temp mortar left that I?d bought with the first lot of materials and I think I?ll use that to grout the first few courses (as opposed to Home Brew). From now on up I?m going to cut the bricks to avoid that V. That was yesterday?s job.

It took a little while to work out what angle I needed to cut each brick and where it should be cut. Just trimming the face wasn?t enough as I had to take some meat off the brick on the sides so that they?d fit alongside each other. A few trial and error attempts (trim a little here, shave a little there) got two bricks to fit together quite nicely, so I saved one as a template and marked up another 15 exactly the same.

Then it was a G clamp to fix the brick to the steps on the deck and go to work with the angle grinder. Two careful cuts on the front face, turn the brick and two on the top, then turn again and two on the bottom. Plastic bottle handy to splash the cuts with water every so often. The size of the angle grinder meant that the cuts weren?t all the way through, so it was a minute or so with a hammer and chisel to finish off. Yeah, a brick saw would have been handy but I?m working with what I?ve got. And they all turned out OK. Quite pleased. Took about 5 minutes per brick.

Those 15 will take me around the dome on the 6^th course to the arch. Then I?ve a lot of tricky cutting and shaving to match the dome to the arch. I had thought of trimming the arch in situ to suit the bricks as I?d seen one guy do. But it?s a flattish arch and only 115mm deep so I?m wary of doing that. If I?d left the arch bricks as 230mm and formed a sturdier entrance I might have done it. But I think I?ll trim the brick to fit the arch instead.

Not yet decided on what type of support I?ll use for the top courses. Inflatable ball? Sand mould? Wooden or polystyrene arches? Bits of stick? Prayer? On the fifth course, the bricks definitely wanted to move forward for the first few minutes after placing so I worked out a cheap and cheerful fix for them. I had 3 or 4 small angle brackets lying around, so I tied a length of string to one end and a weight to the other end of the string, then hooked the bracket over the inside top edge of the brick and let the weight hang over the outside of the dome. Seemed to work at this level. Yet to see if it does on the next.

Hell, it?s starting to look like a pizza oven. I can see places where I could have done better, but everyone is quite impressed so far. Even family discussions on how it should be finished. Thinking of an off white finish with a red dragon mosaic on one side at the moment and perhaps a Fleur de Lys on the other(Welsh heritage you see). But plenty of work to go before I get to that?.

And thanks the tip re the tip re the vinegar, Dave. Maybe as it's an Italian style oven I'll try the white wine variety...

[Greenman]

Howdy Wassa - Lookin' good. I used a similar angle clip with the string and half brick, some stick work, the IT and a few words that may not be found in a standard prayer book! I used some perforated galvanised bracing strap to make my 'clips' and once you get a few bricks along the mortar has gripped enough to remove the clip and move it on. I used wooden wedges to keep the right angle on the brick and filled the resultant holes with home brew mortar once that ring has been finished.

Some have also put a couple of shallow cuts on the tops of the bricks to give something to grip to. The common issue with using a sand mould or a ball is the difficulty in cleaning the face of the bricks on those courses. I found that wetting the bricks (another contentious practice) and getting the mortar to the right consistency helped a lot.

Good luck with the rest of the dome, the more you do the easier it seems to get.

Cheers ........... Steve

[Wozza]

Steve, thanks for that.

I've been soaking the bricks as well. I've seen some advice that says just wet them and other advice that says soak them. I've got a large heavy duty plastic container half full of water and 7 or 8 go in for every batch of mortar. They bubble and fizz for 2 or 3 minutes, then I'm good to go. The bricks are so absorbent that using them dry you can almost hear them sucking the moisture out of the mortar. The Home Brew sticks OK if I mix it right.

You can see my cheap and cheerful clips on the right of the piccie of the oven above. I may make 3 or 4 more - I'm sure I have some angle pieces somewhere.

Just checked on my Complettion Date. Aka grandson's birthday. Lots of people expecting pizza! It means I have 3 weekends to finish the dome, one to wrap it with insulation and render, then 3 weeks for curing and shake down trials. Should be OK, especially as I don't work on Mondays. So 6 three day weekends to go...less any time my wife deems required for other business.

Plan is for the little guy to tap in the keystone to finish the dome and then he gets the privilege of lighting the first fire when we're ready to go.

[cobblerdave]

G'day
Wetting the bricks performs an important function when doing a dry cut oven and that is washing the dry dust from the brick surface. If you don't the mortar wets the dust on the surface it and it becomes slippery. So much for the mortar sticking.
How's that back yard looking? A single cut raises a lot of dust doesn't it
Regards dave

[Wozza]

How's that back yard looking? A single cut raises a lot of dust doesn't it
Regards dave

Looked like a very large bag of light brown talcum powder had exploded next to the deck. Took a while to hose it all down. I'm in the living room typing this and I just ran my finger across the glass coffee table and, yep, very skinny layer of brick dust. Surprised that SWMBO hasn't noticed.

I did a kitchen extension a year back when she was overseas. At one point my son and I used an industrial sized angle grinder to cut a clean edge out of a doorway size hole in a brick wall. Christ, even with the attached vacuum going full blast there was brick duct on every square millimetre of everything in every room throughout the house. I'm sure I was the cause of some spectacular sunsets over the next few days.

[Wozza]

Another couple of courses today to take it past the arch. Bit trickier than I thought it was going to be, but all good. I was going to start another but it's now too steep for the bricks to stick. I tried the angle clip and string trick but that didn't work and it was way too much trouble to cut individual support sticks so...it's the sand mould to finish.

I had some thick ply lying around, so 10 minutes later I had circle cut out and did a test fit. Trimmed it a couple of times and it fits well. I'll grout some of the gaps before I build the sand mould next week and with a bit of luck I might be able to finish the dome.

I could have got a bit further this weekend but the next door neighbours had a kids party and that angle grinder makes a hell of a lot of noise so I had to pass on cutting any bricks.

[Wozza]

Just me talking out loud while I'm having a beer and waiting for the meatballs to cook...

Just read a post from a couple of years back. By Dave as it turned out. Suggesting that when making a sand dome for the last 3 courses or so to throw in a few empty PET bottles to bulk out the area so you don't need so much sand. I would have probably thought of that myself. But after I had finished. Great idea, Dave. Can't wait to tell the Italian guy in work who has a couple of tonnes of sand delievered to make the mould for his barrel shaped oven. Maybe Ll he needed was a a couple of bags.

I'll grout any gaps before I form the mould, but the brick cutting seems to be working ok and there's no too many and those are pretty skinny. May use the last of my super-duty mortar mixed with some crushed brick to bulk it out.

Not sure how long to leave the mould in place, although I've read one post where the guy did the last two courses, fitted the keystone and dig out the sand immediately. Jeez, not sure I have the confidence for that, although the physics says it'll be fine. I can see I'll have to do Brendan's reverse breech birth thing and get in there at some point to finish off. I don't mind pointing a few gaps but I'm not looking forward to removing a lot of excess, rock solid mortar.

Sourced my Vermiculite for the render over the top of the insulation. Place on Anzac Parade that does a lot of hydroponics. Get a 100 kg bag on Saturday and I think, from what I've worked out, that a 5:1 mix with cement will require 30kg of cement. So another couple of bags and I'm good. Oh, and chicken mesh to hold the insulation in place. And lots of wire to hold the chicken mesh.

[cobblerdave]

G'day wazza
Your Italian mate can save himself a bit more shoveling without getting himself a cola habit with a couple of upturned foam broccoli boxes. If they don't fit cut the ends off and cut down with a serrated knife and tape back together.
For your top dome. Cut yourself 2 profile pieces out of thin ply. Cut some slots in them and fit them together as a cross. Makes it easy to keep the hieght and shape right as you form you sand mold.
Drop the sand ASAP it will allow you to clean the excess mortar off the brick face. Repoint later.
Everything comes in tubes these days except mortar it seems. Take a tube of gape filler, it's both cheap and water based. Cut the end off as normal, use a piece of dowel pushed up the tip to push the end out. Clean out the contents, wash clean, fill full of mortar, replace the end.
Fit your mortar tube into a $5 burnings gun and you have one of the easiest ways to repoint I've come across.
Not my ideas I'm only smart enough to recognize a good idea when I see one....
Regards dave

[Gulf]

The form can be removed immediately. If not, there is something terribly wrong with the design. I used a car jack and a plywood disc for my last 4 rows and the plug. What I liked about it was that I was able to drop the jack on a finished row to clean and point where needed. It can the be easily set back into place. And, there is no sand to drag out. But, the disc needs to be small enough to removed through the door .