New 36" Pompeii in Bondi

[Wozza]

Re: New 36" Pompeii in Bondi

OK?bought my bricks at last. Well, most of them anyhow.

Back home after fart-arsing about on holidays for a few weeks and I eventually managed to get a Monday off and take a spin over to Field Furnace and have a chat with their very helpful guy, Lee (they?re not open on the weekends). Told him what I was building and he knew exactly what quantities I needed.

I?d bought the 50mm Hebel blocks on the Sunday from Bunnies so into the back of the 4 wheeler went the 75mm insulation blocks, the floor tiles, a few bricks shaped for the type of door I want and about half of the tapered bricks for the dome itself. Plus a bag of the mortar. That should keep me busy for a while.

Now I realise I bought too much Hebel as I?ll be shaping the blocks to pretty much the shape of the dome. I bought enough to cover the whole slab. Can always take some back and get a refund. Lee strongly recommended laying the Hebel on the hearth and the insulating tiles on top of them without using sand to bed them in. So the bag of sand goes back as well. The reason he gave, and it sounded pretty reasonable, was that there is always some expansion and contraction going on, and if there is sand sandwiching the blocks and the tiles, it will drop into the gaps between them when they expand and prevent them contracting ? so you get some ?creep?. Anyone any thoughts on that?

He also strongly recommended the specialised mortar. But at $45 a bag it ain?t cheap. And I?ll need 4 bags in total. I may have to check up on what the collective thinks of the home brew v the specialist stuff.

Another of his recommendations was to forget about the soldier course. Thought it served no useful purpose ? just bang on and start laying bricks straight onto the insulation layer.

And another of his hints and tips was to get about 5 or 6 courses from the top and then form a dome with builders sand and finish off using that. Seemed like a good idea but?he said if you do that you really need to finish in a day so that you can remove the sand soon after (the following day?) and clean the mortar off the inside. Leave it any longer and it?s a bitch of a job to get off.

And I have one minor problem. The hearth is not absolutely level, dammit. It was spot on when I built the formwork and when we poured the concrete but it must have settled slightly on one side as it was curing. It?s not much ? maybe 5mm over the width of the hearth. But I guess I can level the bricks as I build and it won?t be a big deal.

[Wozza]

Re: New 36" Pompeii in Bondi

Some progress.

I cut all the Hebel yesterday also did the insulating blocks to match. Saw for the Hebel and angle grinder to start the insulating blocks and saw to finish. Did this with a plasterboard template I cut to the inside dimension of the dome. I also dry laid a few bricks out to see what it was going to look like and made a couple of forms for the inner arch.

Regarding the arch, the tapered bricks I've got seem to be twice as long as I need them to be. I assumed they'd be the same length as the dome bricks: 115mm. But they are 230mm. My entry was going to be 460mm long but now laying that out with actual bricks and it looks too long. So...I'll cut the tapered arch bricks in half and the inner arch will be now be 115mm. That looks comparable to others I've seen. They'll be supported by the 230x115 bricks facing out to the side (looking at the dome) so more of a buttress (see piccie).

The outer arch will be a mixture of the 230mm tapered bricks (need to get more of them) and the left over 115mm longs ones in the centre of the arch to form the vent.

I've decided to ignore the slight slope on the hearth. Way too much work to correct it and to be honest, it's not noticeable. Get over it, Wozza! So no mortar and no mixture of sand and clay either. The surface is very smooth and there's no point in trying to make it smoother.

Next, a call on whether the cooking floor is cut to fit inside or I build the walls on top of it. To be honest, from all the info I can find on this, the only real reason for doing it is to be able to replace tiles. Has anyone actually needed to do this? And what's to stop you replacing a damaged tile from the centre of the oven anyway? And if it's on the edge, then I can't see a problem leaving it.

All that versus quite a job cutting a lot of tiles quite accurately (and my angle grinder won't cut deep enough). I appreciate filling in the gaps between tile and dome wall with some cardboard, but I can easily imagine the tiles moving apart during the build. So I will cut the tiles to match the Hebel blocks and insulation tiles already down and build on that. Keep it simple.

What I might do is trim them a little more accurately then I did the Hebel and insulation. Someone mentioned there may be some heat leaking out if there is too much tile sticking out past the bricks. Thinking of that, is 50mm of Hebel a better insulator than 100mm of thermal blanket? I could always wrap the bottom three layers (Hebel, insulation, floor tile) around the outside with offcuts of Hebel and run the blanket from on top of that.

[Wozza]

Re: New 36" Pompeii in Bondi

Wrong piccie in the previous post. Can't seem to upload more than one at a time from my iPhone (and can't do it at all on the iPad).

The first piccie shows the configuration for the proposed arch. The wooden cut out is half the template I've made to support it. The shape and size is 10mm smaller than the oven door I pictured in an earlier post. Second is just me dry stacking the bricks to see what it would look like. The oven floor wasn't down at that stage.

[Wozza]

Re: New 36" Pompeii in Bondi

And finished the tiled floor. Really glad I didn?t try to cut them to fit inside the dome. As an exercise I tried trimming the first one I cut as accurately as possible to try to get a nice curve. This with an angle grinder that couldn?t cut more than 30mm deep so I had to cut from both sides of the 50mm tile. It wasn?t pretty. In fact, it was pretty awful. So what might have taken me ages to do and would have left me with some crappy fitting tiles took me about 2 hours and it?ll look great.

I thought it might have taken a while to work out the best configuration for the tiles for the least wastage but the first attempt was pretty good and I ended up with just a few small pieces left over. Less than a quarter tile.

I then laid out the bricks around a 900mm diameter circle. They won?t fit exactly around the circumference so maybe I?ll add a brick and let the size creep out a fraction or take one out and decrease it a little. Once I?ve done that I?ll cut some plywood and work out how I?m going to make my Universal Tool. I?ll pass on the welding ? no skills in that department (or equipment), so it?ll be screwed and maybe a few good dollops of Araldite or similar.

[david s]

Re: New 36" Pompeii in Bondi

If you are using a 4" angle grinder with a diamond blade to cut, it won't cut very deep. It is well worth buying a 5" angle grinder (I got a cheap Ozito and its done tons of work) because it will give you deeper cuts, with more power and a real time saver over a 4". Wear eye protection and a dust mask.

[cobblerdave]

Re: New 36" Pompeii in Bondi

G'day
I secound Davids on buying cheap and big with the grinder. They tend to ingest a lot of brick dust which is not good for there internals.
Watching with interest
Regards Dave

[BrendanLovesPizza]

Re: New 36" Pompeii in Bondi

If you are not buying a brick saw to cut your bricks then forget it.

I was going to buy a $500 dollar brick saw use it then sell it again. Lucky for me my landscaper mate has two bricksaws so borrowed one for 6 months.

I wouldnt start without a bricksaw my 2 cents.

[Wozza]

Re: New 36" Pompeii in Bondi

I bought the bricks ready cut - right size and tapered. So as far as I know the only cutting I have to do is maybe trim a brick on each course so that it fits (or maybe that should be two bricks? Each one connecting to the arch?) And maybe trim some as I get close to the top of the dome.

That said, next trip to Bunnies and I'll check out the price of the larger angle grinders. As David said, the Ozitos are good value. I bought one of their drop saws for a small project and it lasted long enough to do the job.

Threw another piccie up to show the state of play at the moment. Easy to see where I have to cut the bricks to fit up against the arch support. And decisions I have to make:

Do I leave a thermal break between the inner arch and the outer? In two minds at the moment after spending a couple of hours browsing the forum last night. That can wait in any case.

And do I take the oven floor right to the edge of the hearth slab. I need another couple of tiles in any case to take it to the front to the landing. Not sure if I stop there and finish off in front of the oven with whatever I decide to put on the rest of the hearth. And again, not urgent as yet.

And anyone have any advice on whether there are any advantages in forming up the inner arch sooner or later? And naturally, if anyone can see anything obviously wrong at the moment...

[BrendanLovesPizza]

Re: New 36" Pompeii in Bondi

Always build the inner arch first. It sets the platform for the dome. Get your it tool sorted and functional. You basically build the dome around the inner arch. Think twice about angle grinders. Buy steel cutting blades, compound blades will break and fragment into your arm legs face etc.

[david s]

Re: New 36" Pompeii in Bondi

you need a diamond tile cutting disk.

[Wozza]

More progress. Although with the problems in seeing pictures at the moment I'll wait a while before posting any.

Cut my tapered bricks for the arch. Used the diamond disc on my angle grinder and cut 4 sides, tap with a hammer and job done. Made a form for the arch and fitted it all together. It seemed to go ok. It's well buttressed but as it's a rather shallow arch I'm not sure if this first attempt will be my only one. Not sure how long to leave the form under it. If it's going to fail then I'd rather find out sooner rather than later.

I'd thrown a tarp ove the whole thing last week as I'd cut a plywood circle to which I'd fitted my Indispensible Tool. Didn't want tit o get wet...but the thing warped in any case. Curses...

Not too bad, but maybe it would have been a good idea to have a few bricks sitting on it when I fitted it to keep it flat. Nearly forgot to cut it into 3 pieces so I can get it out when the dome is built but I did that earlier. The started on the first couple of courses.

Just about finished the third so far. I haven't connected to the arch supports yet - might trim a couple of bricks and do that tomorrow. Must have uses 2/3 of the bag of mortar I'd bought. Must check on the recipe for home brew later. But the ready made stuff was really easy to work with. Mix it right and it sticks well, doesn't dry too quickly but quick enough so that it gives good support after a few minutes and does the job really well. I soaked all the bricks before I used them. About 5 minutes or so. Tempted to get another couple of bags of the mortar but the trip out West to get them is a pain in the arse.

[cobblerdave]

G'day
Good news! All your pics are still there!
All you have to do is click on the icons and they appear.
Might be a good idea to go back to your first post and hit the edit and and put a explanation that the pics will open up when "clicked" on and it's done!
Await the new pics
Regards dave

[Wozza]

Ah, the pictures do seem to come up ok now. Maybe it's all the previous ones that only appear as a file name. Anyway, that's where I'm at as of yesterday arvo. I actually got the best part of the third course after I took the picture.

The mortar is still a little soft this morning. I covered it all with a tarp last night so maybe a day in the sun today will help it cure. My only worry is that the arch seems too shallow. I guess if It was a semi circle then that would be the most robust. But I've tried to match the contour of the door I'll be using. I like the way it looks, but does anyone think it may be too weak? Not sure how long to leave the the form in, but it will be a few days minimum. Then how do I test if it's OK? As the dome is built up around it, does that put more stress on the arch or help to support it? And

[Wozza]

Read up on home brew these last couple of days. I'?ve just about finished the ready-made stuff (at $45 a bag) so thought I?d check the cost of mixing my own at the accepted ratio of 3:1:1:1. Sand and cement wasn?t going to be a problem but would I be able to find the lime and the fire clay?

Anyway, we were meeting the family for a couple of drinks at The Rocks brewery in Alexandria (for those who know Sydney) and there?s a big Bunnies just around the corner so I called in. Parked in the tradies area and low and behold there were bags of everything I needed all within a few meters. A 20kg bag of each and the total cost was just over $40. Very happy with that.

Starting the 4^th course yesterday and I realised how much more mortar you use between the bricks as you get higher up the dome. Scrimping on the expensive stuff would have been frustrating (notwithstanding a nearly three hour round trip to pick it up) but now I feel quite happy laying it on pretty thick. And that was after taking off the ten bricks or so I?d done on the third and redoing them. I?d started the course at the arch and by the time I?d got to the middle, the joints in the third course were starting to line up with joints in the second. I doubt if it mattered but it just didn?t look right and that?s the internal part of the oven that everyone will see. So?down they came and I started in the middle and worked outwards. Looks much better.

But now starting to get that inverted V at the bottom of the bricks as they lean a little further in. Guess this is where a brick saw would come in handy. A little mortar will fill those gaps on this course but they ain?t going to get any smaller.

Thinking out aloud here, so bear with me?

Rather than trim the bricks, which is an almighty pain in the butt without a brick saw, I wonder if it would be possible to cut a few bricks into (say) 20mm thick slices and then cut 3 or 4 triangular pieces out of each slice that would fit those inverted Vs. You?d get at least 20 out of each brick. Bit of mortar in the gap and then press the triangle into it flush with the internal face of the dome. Guess it would look a little mosaic-like but you?d get a nice smooth finish. Anyone know anyone who has tried it?

And in passing, how come if a pint at The Rocks is $9, a half pint is...wait for it...$7! WTF?

[Wozza]

And while I'm on line, here's a piccie of my Indispensable Tool in action.

The swivel was about $3. I just hacksawed the little wheel off, drilled a hole in a bit of wood I had lying around and fixed one to the other with a small bolt. The galv clip on the end was $1:50 and I screwed that to the end of the wood. It was just the right size. Took me about half an hour to make it. My daughter thought it came especially with the 'Pizza Oven Kit'. Isn't Daddy clever! But she's much more easily impressed than her Mum...

Incidentally, the old bricks and a large rock on the oven floor are to try and keep the plywood flat as it had started to warp.