Dome on oven floor

[Rinrat86]

Our WFO is on top of 2" fibreboard (specifically Kaowool HP board). We've cut the oven floor out with the plan to build the dome on the oven floor.

The only reason I am seeing for having the oven floor inside of the dome is to facilitate easier replacement of floor bricks if necessary.

Is there any other reason why I shouldn't build the dome on top of the floor?

[mrchipster]

Re: Dome on oven floor

No other reason and in fact you could still replace most of the bricks even with oven on floor, just the ones under the wall could not be replaced and those arr at the edges.... Not much cooking being done there anyway and the edge is a low wear area also.

[Rinrat86]

Re: Dome on oven floor

So the concern that is going through my head is whether the weight of the dome pressing down on the floor could compress the fibreboard near the edges such that the floor is no longer properly flat/level.

[NCMan]

Re: Dome on oven floor

I built mine on the floor and would do it exactly the same way again. Honestly, I can't see a case where anyone would ever really have to replace a brick and I'd probably enjoy just watching someone do it. I imagine that somewhere, someone has done it, but why? It'd be cheap entertainment to watch, to say the least. Seriously, though, it works either way. I just couldn't see going through all that extra work for nothing. The only thing I'd recommend is if you build on top of the floor, don't leave too much of the floor brick extend out past the dome walls, as they could bleed heat into an area (outside the dome) that would be a waste. I left mine protrude out about an inch or so, just so the dome walls weren't sitting right on the edge. Best of luck to you!!

[Rinrat86]

Re: Dome on oven floor

Thanks NC, did you build on fibreboard?

We're looking at (a) do we proceed atop the floor; (b) do we cut the floor smaller; (c) do we increase the size by building the dome outside of the floor we've cut - which would mean futzing with the fibreboard to increase the size of the base with the scraps from the initial cut, and adjusting the planned entry arch.

[mrchipster]

Re: Dome on oven floor

Thanks NC, did you build on fibreboard?

We're looking at (a) do we proceed atop the floor; (b) do we cut the floor smaller; (c) do we increase the size by building the dome outside of the floor we've cut - which would mean futzing with the fibreboard to increase the size of the base with the scraps from the initial cut, and adjusting the planned entry arch.

Ceramic board has a compressive strength deformation of 5% at 40 psi.

On a 2 inch thick piece of ceramic board that would be a little over 1/16 of an inch.

The surface area of a 42 inch dome using half 9 inch bricks has 658 sq inches in contact with the floor, not counting the arch.

In order to reach 40 psi your oven dome would need to weigh in at about 13 tons to compress that 1/16th of an inch.

I think you are safe.

[Rinrat86]

Re: Dome on oven floor

Many thanks! I'd just started to research the compressive strength numbers and was trying to figure out what they meant, so I really appreciate your calculations. Even better I've found out that the board I have has a rating of 5% at 75 psi.

[Tscarborough]

Re: Dome on oven floor

The only problem with building it on the floor is that you can stick your peel in the joint; with the floor inside the dome, there is no stickable joint there. I always build on the floor though for a better weight distribution of the dome onto the insulation.

[mrchipster]

Re: Dome on oven floor

Many thanks! I'd just started to research the compressive strength numbers and was trying to figure out what they meant, so I really appreciate your calculations. Even better I've found out that the board I have has a rating of 5% at 75 psi.

I guess you oven would be aproaching 25 tons, Better build a strong stand...

[Toomulla]

Re: Dome on oven floor

I guess you oven would be aproaching 25 tons, Better build a strong stand...

Is that two and a half tonne?

[mrchipster]

Re: Dome on oven floor

Approx 660 sq inches of surface area of dome in contact with the board

Times 75 lbs per sq inch

Equals 49,500 pounds or just under 25 tons.

To cause 1/16 inch of compression for his board assuming equal weight distribution.

[Toomulla]

Re: Dome on oven floor

Thanks I get your point I had not read back the string and was confused that an oven would weigh 25 tonne

[NCMan]

Re: Dome on oven floor

Thanks NC, did you build on fibreboard?

No, I built my oven on perlcrete @ a 1:8 ratio. Just my preference.