Cast Iron Cauldron

[PizzaFarm]

Hi, first off I want to say that we built a Forno Bravo brick oven at our local farmers market and it is huge success. We made a few mistakes but it produces fantastic pizzas very quickly.Many thanks to this site for guiding us through our build.

Now we want to take it on the road to do another farmers market. We grow all the toppings for the pizza - from the sauce to the sausage everything except the flour for now. This is about the only way you can make a living at farming as I can see it.

I have researched the site for mobile ovens and there is a lot of good builds to learn from. I have acquired an old cast iron maple syrup boiler (large round pot) in pretty good shape, 36 inch in diameter, and wieghs about 300 pounds or so (guess). I thought of cutting an achway door into the steel, place the couldron upside down on good strong insulated base, I would then insulate the dome and cob over the insulation using wire mesh.

I am going to transport in my 3/4 ton pickup for now, until I sell enough pizza to build a suitable trailer. Any thoughts on this build. I need to get up and running quickly, as market season is here.

[Wiley]

Re: Cast Iron Cauldron

Depending upon the kettle's age I suspect you will have some difficulty cutting and shaping and welding to the cast iron kettle. I don't have an exact date but at sometime in the mid 20th century alot of what was made of cast iron became to be made of cast semi-steel which while having alot of the properties of the cast iron had fewer of the drawbacks, primarily less brittleness.

When the molten iron was poured into the mold to form the kettle the sand binder (which in older times was molasses) was charred and in so charring released lots of CO2 and CO. This was carbon incorporated into the molten metal forming carbides with the iron. These carbides are what makes drilling and mechanical cutting of cast iron so difficult. Cutting can be done with a torch (oxy acetylene or plasma) but the finish surface will not be nice, for another characteristic of cast iron is free carbon in the form of graphite which doesn't lend itself to torch cutting nicely. It is possible to change the structure of cast iron to make it malleable by heat treatment, and example is a common "C" clamp, but I doubt that was done to your kettle. Anyone who has attempted to weld cast iron will also tell that to do so is problematic. It can be done, one of the easier methods being with a high nickel rod and lots of preheating.

I would suggest you inquire into getting an old condemned propane tank and proceed using it. It is made of steel which is easier to work and weld to. There are several builds on this forum using such tanks. You might check out my thread "Steel Dome Oven".

For a while the high price of scrap steel made finding a condemned tank more difficult. However, recently several have made their way into the scrap market locally and so perhaps you might be worth checking in your local area. By several I personally know of one yard which had as of last week 16 spherical tanks for sale. I informed John Shelley of this forum who built and runs Dented Bouy as he was in the market for such a tank for a second WFO. He said he had found three at another yard as well as a second 60 inch bouy.

I would also think that you could sell a cast iron maple syrup kettle for more than the price of a condemned propane tank.

Hope this helps,
Wiley

[PizzaFarm]

Re: Cast Iron Cauldron

Thanks for the reply, I enjoyed reading about your oven, it is going to be very helpful. The pressure is on to come up with a useable oven for this market season, I plan to use the winter to do a proper build with a dedicated trailer, perhaps a precast model etc. When I saw this cauldron sitting out there it looked like it might be the answer for a quick and dirty oven. I may have to wait until next season to bring the show on the road. If I come up with something I will certainly share the results. Thanks again.

Adam

[PizzaFarm]

Re: Cast Iron Cauldron

On the good advice from this forum, I decided to turn the old cast iron pot into an awesome wood fired BBQ, not a mobile pizza oven. We did get our portable oven built and on the road in time for our farmers market opening weekend. It wasn't pretty, but it did cook great pizza. It was a very simple build and only took a couple of days. Not as much insulation as I would have liked, the top of the dome runs at around 250 degrees so I can slow cook the our sausage and bacon on it while the oven heats up. I takes about an hour to heat up for pizza cooking. It ran for over 7 hours straight on the Saturday and we made 40 or 50 pizzas, the floor maintained a temp of 550 - 600 degrees around 850 on the dome. We are now in the process of making it look nice. It was a little nerve racking lifting it off of its platform with the tractor and placing it on the trailer, my wife couldn't watch. We will be on the road again this weekend.