Fio's 35" Oven

[Fio]

After Installing the casting, I closed the gap

Casting the exhaust was a LOT of work. I made several mockups and spent a LONG time building the mold.

But once I installed the exhaust casting, I could continue laying bricks, cutting them, and filling out the dome behind the vent. That was my biggest challenge - what will support the bricks behind the vent? The vent itself! I dry fit the bricks for the fifth and sixth courses - probly too much work, but I liked the results. I've worn through three cutting wheels, but the cheap Harbor Freight saw is still going strong.

Cutting the bricks to fit in behind the vent, in a vain attempt to maintain some sort of circularity, was sheer madness. I'm trying too hard or not working smartly.

Things never work out as neatly or cleanly as you plan. Using computers to calculate dimensions of voussoirs means diddly because firebricks are not exact and the human machine cutting the bricks and laying them is vastly flawed.

[DrakeRemoray]

That is looking great!! You passed me up!

Drake

[Kinsman]

Looking good, Fio. Won't be long now.

I am kinda stalled but not for long. Work is getting in the way of pleasure here......

[dmun]

Casting

Your vent casting is very slick. Did you think the angle irons were necessary? You would think the refractory casting would do the trick by itsself.

Your comment on the work to make the form reminds me of the architect that said to make a ferro-concrete house you build a house on the outside, a house on the inside, then after the pour, you tear down the first two houses.

[Fio]

Nice observation about the casting!

Your vent casting is very slick. Did you think the angle irons were necessary? You would think the refractory casting would do the trick by itsself.

Your comment on the work to make the form reminds me of the architect that said to make a ferro-concrete house you build a house on the outside, a house on the inside, then after the pour, you tear down the first two houses.

I needed the angle iron to rest the casting on. The casting itself was not wide enough to span the gap in between the uprights of the entrance. I considered making it bigger, but I didn't want to make it too big and risk cracking.

The comment about the casting is correct. I built the mockup, then built two forms, one to fit inside of it and one to fit outside of it. When the casting was hard, I tore away the two styrofoam forms.

By the way, I plan to finish the dome this weekend and I'll try your "cruciform" brick configuration for the top.

[Fio]

Finishing the Dome Part 1

For the last four courses, I decided to cover the entire form with aluminum tape. This would prevent the smaller sized trapezoidal bricks from slipping in the voids between the vanes, And it would effectively mold the mortar injected into the triangular voids to the shape of the dome. My aim is to prevent chunks of mortar hanging from the dome that could end up on a pizza (OUCH!). Actually, once I tear out the form, I'm going to run a scrub brush along the inside of the dome to loosen any debris.

Another idea I thought of, but did not try, was using MonoKote It's a shrinkable mylar covering used for model airplanes. It's strong, but expensive. It would create a perfectly smooth, taut covering to span between the vanes of the form to provide a seamless surface for leaning the bricks against. It's pretty strong, but I wouldn't push it.

Another advantage of covering the form is that you can write on it. I found that if I carefully laid out the cut bricks on the form, I would never get them to fit properly when I mortared them later, so I would number them and draw alignment marks on the brick and the tape. This made alignment when mortaring a snap.

Do you think this is a waste of time? Should I just cut, fit and mortar in one step? I decided I couldn't do this because I was working alone. With two people working, one cutting and the other mortaring, this would not be necessary.

[Fio]

To finish, I wanted to avoid creating ever-tighter rings of bricks.

I planned to use dmun's "cruciform" idea for the top (brilliant idea; leave it to a clockmaker!), but I found that I couldn't really do a proper cross. So, I started with a bridge across the top and cut other bricks to fit in around it. It's a neat alternative to making smaller little rings of bricks. I had HUNDREDS of little brick wedges laying around from cutting all the other trapezoids, so it was easy to find wedges to drive in the gaps.

But it involved a LOT of cutting. After a while, I used the spinning wheel of the abrasive saw as a shaping tool - a huge angle grinder, as it were. It took a lot of trial and error, but I was pleased with the results. Most of the brick were wedge shaped, which (I hope) will discourage them from collapsing.

Here's where I made a mistake. I cut the bricks to fit snugly, but I didn't leave enough room for mortar. That made fitting them together later a bit of a challenge. They sure looked pretty when they were dry fit, but getting them to sink in the surface of the form was a bear and I don?t think I went all the way in some cases.

[Fio]

On Sunday, I mortared everything together while dodging a rainstorm

I was SO glad I numbered the bricks and drew the alignment marks. It made mortaring so much easier. If I had a helper, I wouldn't have needed to do a two-stage construction.

I was annoyed at the large triangular gaps that developed on the top ring and I was just too impatient to cut little triangular plugs. Also, where the circle intersects the vent the curve becomes aggressive, and I got some big gaps there. Where I could, I cut fillers; otherwise, I just squirted mortar in from the grout bag.

When I got the last few bricks, it was difficult getting them to fit properly. I had to use a dead blow mallet and in the process, mashed the tops of some of the bricks. I hope to God that I didn't seriously crack or break anything. Before I filled the grout bag, the entire dome was rock solid - nothing moved. I hope it won't collapse when I remove the form in a few days.

After it was done, I put frosting on the cake. It looked mahvelous - until the rains came. More on that later.

[DrakeRemoray]

That looks great Fio. I may have to adopt your numbering scheme, the bricks certainly require a lot more cutting as the rings get smaller.

Drake

[Fio]

Here's What the Rain Did To The Cladding

The wind blew the tarp partway off my completed dome, and the rain washed away some of the mortar cladding. Yuck.

I had to repair it later. Then I added the Chimney. I more or less smeared mortar around the vent manifold and plopped the chimney on top, then I smeared/smoothed the mortar with my fingers.

[Fio]

I tore out the form and looked inside.

The moment of truth arrived. I tore out the form and peered inside. I was pleasantly surprised by the appearance of most of it, especially the dome cap construction.

But there were some gaps. I knew this while I was building it. And I did not fill them all completely. I hope the whole thing holds up.

[DrakeRemoray]

I think it looks great! When are you going to start curing it?
Drake

[james]

Excellent! Should be be very proud. The oven is full coated on the outside, holding in heat and air, so I don't think you should worry about the gaps between the bricks.

What does everything think about that?

Pizza is right around the corner.
James

[james]

Extra cooking floor firebricks

Fio,

Can you remove any of the extra firebricks that aren't under the oven? They will draw heat away from of the oven, so if you can remove them that would be good. No big deal if you can't.

Then, your loose insulation will come all the way down "around" the cooking floor.

James

[CanuckJim]

Gaps

Fio,

You've done a fine job. Looks great and will work well. Personally, however, I'd get in there and mortar up the gaps to prevent hot spots on the brick edges, which will cause undue wear. Mix your mortar fairly dry and push it in with a pointing trowel.

Jim