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Well, after many years cooking pizzas, a few wonderful year with a cob oven outside, the brothers and I have decided to take the pizzas on the road. I've found so much helpful information here so I'll give back and document as much of the build as possible on in this thread.
Goal: A cast refractory concrete oven mounted on a standard 4x6 utility trailer. Trailer will be outfitted to comply with Colorado Health Regulations, including a sink with hot water heater (or oven-supplied hot water with pump, generator, and refrigerated prep rail.
I have the advantage of having an experienced welder/brother/partner in this endeavor, but If you want to do this, any decent trailer fabricator could provide you with the trailer built to spec.
Begin with:
4x8 utility trailer with 3500lb axle and 15" tires. Here in denver I can get one for about $1000.
The dome will be cast with a heavy castable refractory concrete, still working on the exact mix we can source here in denver. After speaking with a VERY helpful salesman at United Western Refractories here in Denver, and thinking it'd be good to go in and visit with the guys next week, as this is a very different project than their usual business. I got the feeling they'd be happy to chat and give suggestions.
I will be using the builds by MrG and JoeyValderain as models, thanks to both of you for posting your builds
I used Wolfram|Alpha—Computational Knowledge Engine to calculate the surface area of half a sphere with an outside-outside diameter of 44 inches, which would be an inside floor diameter of 40 inches.
using that, I come up with a surface area of 19.24 sq feet, and then using the concrete calculators http://www.concrete.com/calculators/concrete-materials-calculators i came up needing 4.6224 Cubic feet for the dome. Right now we're going to ignore the fact that it's going to have straight sides and also a cast opening. at 160 lbs per cubic feet, that's a weight of 739 for the dome, which is great...we're looking to keep everything under a ton, so looks like even with a slab under, and an entry way, we should be OK.
In all of this, I've been looking to keep my weight down and my oven size reasonable...I saw an Concessionaire model built by Into the Fire in Boulder, CO, and it was massive and looked VERY heavy. I want something more portable, pullable by small pickup, and not as expensive :-) Something you could fire up at home, then pull up onto a sidewalk and start slinging pizzas ASAP.
Oven floor:
I'm still in discussions with the health department, but am concerned that they may want to see a solid oven floor. state regulations state: "Multi purpose food contact surfaces shall be: smooth, free of breaks, open seams, cracks, chips, pits, and similar imperfections". I can't imagine a firebrick oven floor would get past that. Can you? Unless an oven isn't a multi purpose food contact surface? However, it looks like the Forno bravo oven that The Fire Within uses a forno bravo oven with a 4 piece floor, with BIG 1/2" cracks in between the tiles. I'd love to hear thoughts about this (it's not my concerns, it's Health Code)...if I can't use firebricks or a segmented floor, it will either be a cast floor, which will crack eventually anyway, or soapstone, which is going to cost $$$
Below the oven floor of 1.5 inches will be 2-4 inches of ceramic insulation board, and then ??? I'd like to avoid a slab of concrete because of weight. Could I use 2 sheets of 3/8 inch durarock cement board instead?
The oven will be supported in a cradle of angle iron, leaving us with storage space below.
Both MrG and JoeyValderain cast their ovens separately from the bases. Lacking an engine lift or forklift, I intend to build from the bottom up and pour the dome on the trailer.
For securing the oven dome to the trailer I'll have have bolts go from the angle iron cradle up through the insulation board and hearth, to be cast into the oven dome. I'd imagine we'd put nuts or something on the end of the bolts to give them more surface area to grip the concrete. I don't want this oven going anywhere.
I'll need hot water to a 90 degree temp. I could buy a propane hot water heater from an RV supply, but I'm going to be making my own heat whenever the unit is in operation. What do folks think about casting a copper pipe into the dome or hearth and pumping the water through? I'll have no way of moderating the water temp, barring mixing with cold, which would require 2 tanks...any thoughts on this?
That's where I am today. I'll post a few sketches and keep this updated as I talk with suppliers and the health dept on Tuesday. I'd invite comments and suggestions, and envy all of you who got to build your ovens without the Health department telling you what to do
If any of you engineers can design a silent, less than $700 oven-created-steam powered electrical generator to power my fridge I'm required to have on board (no ice for chilling ingredients), I'll send you a gift certificate to pizza hut.
Goal: A cast refractory concrete oven mounted on a standard 4x6 utility trailer. Trailer will be outfitted to comply with Colorado Health Regulations, including a sink with hot water heater (or oven-supplied hot water with pump, generator, and refrigerated prep rail.
I have the advantage of having an experienced welder/brother/partner in this endeavor, but If you want to do this, any decent trailer fabricator could provide you with the trailer built to spec.
Begin with:
4x8 utility trailer with 3500lb axle and 15" tires. Here in denver I can get one for about $1000.
The dome will be cast with a heavy castable refractory concrete, still working on the exact mix we can source here in denver. After speaking with a VERY helpful salesman at United Western Refractories here in Denver, and thinking it'd be good to go in and visit with the guys next week, as this is a very different project than their usual business. I got the feeling they'd be happy to chat and give suggestions.
I will be using the builds by MrG and JoeyValderain as models, thanks to both of you for posting your builds
I used Wolfram|Alpha—Computational Knowledge Engine to calculate the surface area of half a sphere with an outside-outside diameter of 44 inches, which would be an inside floor diameter of 40 inches.
using that, I come up with a surface area of 19.24 sq feet, and then using the concrete calculators http://www.concrete.com/calculators/concrete-materials-calculators i came up needing 4.6224 Cubic feet for the dome. Right now we're going to ignore the fact that it's going to have straight sides and also a cast opening. at 160 lbs per cubic feet, that's a weight of 739 for the dome, which is great...we're looking to keep everything under a ton, so looks like even with a slab under, and an entry way, we should be OK.
In all of this, I've been looking to keep my weight down and my oven size reasonable...I saw an Concessionaire model built by Into the Fire in Boulder, CO, and it was massive and looked VERY heavy. I want something more portable, pullable by small pickup, and not as expensive :-) Something you could fire up at home, then pull up onto a sidewalk and start slinging pizzas ASAP.
Oven floor:
I'm still in discussions with the health department, but am concerned that they may want to see a solid oven floor. state regulations state: "Multi purpose food contact surfaces shall be: smooth, free of breaks, open seams, cracks, chips, pits, and similar imperfections". I can't imagine a firebrick oven floor would get past that. Can you? Unless an oven isn't a multi purpose food contact surface? However, it looks like the Forno bravo oven that The Fire Within uses a forno bravo oven with a 4 piece floor, with BIG 1/2" cracks in between the tiles. I'd love to hear thoughts about this (it's not my concerns, it's Health Code)...if I can't use firebricks or a segmented floor, it will either be a cast floor, which will crack eventually anyway, or soapstone, which is going to cost $$$
Below the oven floor of 1.5 inches will be 2-4 inches of ceramic insulation board, and then ??? I'd like to avoid a slab of concrete because of weight. Could I use 2 sheets of 3/8 inch durarock cement board instead?
The oven will be supported in a cradle of angle iron, leaving us with storage space below.
Both MrG and JoeyValderain cast their ovens separately from the bases. Lacking an engine lift or forklift, I intend to build from the bottom up and pour the dome on the trailer.
For securing the oven dome to the trailer I'll have have bolts go from the angle iron cradle up through the insulation board and hearth, to be cast into the oven dome. I'd imagine we'd put nuts or something on the end of the bolts to give them more surface area to grip the concrete. I don't want this oven going anywhere.
I'll need hot water to a 90 degree temp. I could buy a propane hot water heater from an RV supply, but I'm going to be making my own heat whenever the unit is in operation. What do folks think about casting a copper pipe into the dome or hearth and pumping the water through? I'll have no way of moderating the water temp, barring mixing with cold, which would require 2 tanks...any thoughts on this?
That's where I am today. I'll post a few sketches and keep this updated as I talk with suppliers and the health dept on Tuesday. I'd invite comments and suggestions, and envy all of you who got to build your ovens without the Health department telling you what to do
If any of you engineers can design a silent, less than $700 oven-created-steam powered electrical generator to power my fridge I'm required to have on board (no ice for chilling ingredients), I'll send you a gift certificate to pizza hut.
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