WFO at the cove

[tommo21]

I am building a 42 inch oven out of fire bricks some reclaimed some new but all second hand.
I have had the slab down for a while. It is a corner build and at ground level behind a retaining wall.

[SableSprings]

Remember to set the "new" fire bricks aside for the cooking floor. It's always interesting to see photos of the starting location included in the build thread. Ground level behind a retaining wall sounds like an interesting situation...looking forward to your progress...and pictures

[tommo21]

Thanks!
I have used the better fire bricks for the floor. however i only had a grinder and bolster when i did put the floor down, the edges are not as neat as could have been.
I bought a 14" saw second hand in the end to cut down on dust.

[tommo21]

I purchased Cal Sil board from a retailer of thermal ceramics, I ended up mortaring the board down as the base beneath was somewhat uneven. The moisture from the mortar didn't seem to affect the board too badly.
The cal sil was able to be cut with a timber hand saw.

My site is not as tidy as others... but i plan to pour concrete bench tops over and around the supporting slab, this will hide all the rough edges!

I took a few extra measures to ensure my oven stays dry. I picked up the info from other builders on here ways to manage ground moisture. Thanks to those guys.

There is builders plastic under slab, waterproof additive in the concrete mix, under tile waterproof membrane to the top of the slab and finally i laid some porcelain tiles i had left over to raise the cal sil board a bit in case of ponding water.
Cheers

[tommo21]

The floor was cut prior to my wet saw purchase, i leveled the floor with a reasonably dry 1:1 sand and fire clay mix.

[tommo21]

I used some used form ply for protect the cooking floor. which raised the IT fixing point by about 20mm. I also used cardboard to create the expansion gap around the floor.
I crafted an IT tool from some threaded rod, a turnbuckle, building bracket and a castor wheel. Took some time to fabricate, but i would be building blind without it. I feel i might still cut a quarter circle form out of ply to check my curvature as i progress further up through the brick chains.

[tommo21]

I tried to get the floor bricks to touch with minimal gaps. However the bricks are not perfect rectangles. I am hoping i have made the gaps small enough.

[tommo21]

A few pics of the first few chains and some inner arch bricks.

[tommo21]

In terms of cutting dome bricks.
the 14" wet saw is perfect for keeping dust to a minimum, but getting the angles right is still tricky at the moment.

The chain around the floor was not cut at all. 1st chain i cut a side angle of around 5 degree and these are laid flat.

Im sure it sounds logical but where i cut the side angle to suit the curve i struggled to lay the chain as there was no room for mortar and no room to adjust.
I think having a bit of an 'open' angle in the brick join makes laying easier and quicker. I assume some builder who are making exact cuts almost have no mortar in some joins.

I need to keep an eye on level around the chain too. It is slightly off. and i am finding some correction of the dome circle now i am using the IT tool as the floor course was laid prior to the IT tool. will have to wait and see if my correction is obvious once finished.

I have started cutting a slight side bevel on the 3rd?? chain to avoid the vee.

I will need to build a jig before i go any further with cutting. I am using mr chipster's method for cutting and will copy his jig and have used deejoyah's dome calc spreadsheet thanks guys!

[tommo21]

another chain with timber shims, the shims were hard to remove after 24 hrs.
might switch to brick shims, or slightly loosen off the timber shims after a few hours and remove after 24 hours.
I am using the fireclay mortar.

[tommo21]

As mentioned i am using the fireclay mortar for my build. Currently i have used the 4:1:1:1 ratio of sand, fireclay, cement and lime.

I found adding a bit more fireclay makes the mortar easier to use.

I have also found another mix ratio of 10:6:2:3.

Should i be modifying my mix to be closer to the second mix? Which will be stronger?

[david s]

The higher proportion of clay is likely to result in shrinkage cracks. The usual ratio is 3:1:1:1 sand, clay, cement, lime. Steer clear of bentonite as it's extrely small particles lead to greater shrinkage than other clays.

[tommo21]

I ended up finding 25kg bags of fireclay at a mile end (for locals) pottery shop for about $70. cheapest i could find. I will have to double check the composition tonight

[tommo21]

I have finished the dome - not as neat as i had strived for, but i wanted it to go up real quick.
I need to hit the inside with a grinder to tidy a few spots ut all in all very happy to be at this point.
I must say my hat goes off to those builders who maintain tight brick joints, good vetrtical bond and mostly a neat arch to dome transition.
Very tricky part that last one.

I will add some pics soon.


But i want to get some input about the vent arch - i entertained possibly doing a cantilevered approach but i feel the work involved is not worth the return.
So what i think i will do i build the shortest length vent arch maybe one brick length.

[tommo21]

How are others attaching stainless steel flue to the vent arch without using a base plate?