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pjcampo 09-16-2008 03:57 PM

Form for 24" ?
Could someone recommend something easy that could be used to help me form a 24" dome? I saw these styrofoam halves but can't imagine they could hold the weight.... maybe they will hold it enough?

24" Smoothfoam Ball - sold as 2 hollow pieces that you glue together. Wall thickness is 7/8"

Dutchoven 09-16-2008 05:09 PM

Re: Form for 24" ?
This would be difficult to get out after you are through with the dome...not something you should burn out...:eek: ...but perhaps you could use it to create a from from damp sand...but you would end up with a dome less almost two inches...I would suggest getting some 3/4 inch plywood and cutting out semicircles in 12 inch radius...could either use the pieces cut out as a movable template or use the larger piece to create from from the above mentioned damp sand
Good luck


Originally Posted by pjcampo (Post 41143)
Could someone recommend something easy that could be used to help me form a 24" dome? I saw these styrofoam halves but can't imagine they could hold the weight.... maybe they will hold it enough?

24" Smoothfoam Ball - sold as 2 hollow pieces that you glue together. Wall thickness is 7/8"

pjcampo 10-02-2008 11:29 AM

Re: Form for 24" ?
I thought we would just break the foam afterward. If we propped it up a few inches to bring it up even with the first course, it would give us room to break it or cut it after whatever held it up (wood or bricks) was removed from below.

I was thinking a 2.5" first course and then a 12" "perfect dome" for a 14.5" internal height. Any suggestions? My wife and I are a bit concerned about our ability to be very uniform and even without a solid form on the inside to keep us in the right direction. we are the type that need boundries and limiters and things like that!! :eek:

We don't know exactly what we're doing and since ours is so small compared to everyone elses, we are a little bit on our own!!! :)

Derocherconstruction 10-02-2008 05:38 PM

Re: Form for 24" ?
You could cover the styrofoam with plastic sheeting, or duct tape for a clean release after casting or brick laying.... Jim

dmun 10-02-2008 06:19 PM

Re: Form for 24" ?
The problem with full internal forms is that you can't clean up the joints as you go along. Since your oven is so tiny, why not build it upside down in a sandbox? You could create the spherical form in the damp sand with a spoon on a fixed pivot with string, and then when you got the shape you wanted, you could spray it with molasses to fix it. Wait, is molasses the fixative they use with foundry sand? I forget. In any event, you could use this method to build your full dome, and if you used proper refractory mortar like ref-mix it would be plenty strong enough to turn upside down when you were done, and you would be able to clean up your mortar joints as you went.

Just a suggestion, this isn't based on actual experience.

Johnny the oven man 10-02-2008 06:22 PM

Re: Form for 24" ?
In Oz we can get styerene boxes, usually from the fruit vendors. They work perfectly.

pjcampo 10-23-2008 02:31 PM

Re: Form for 24" ?
1 Attachment(s)
Well I went ahead and did it. I've been procrastinating long enough. Here is the finished dome. It took me about 6 days working several hours a day. There is of course a lot I would have done differently but I will save it for next time.

I did use the styrofoam dome from plasteel. Now I realize they also sell the 30" version. Hopefully I will be able to clean up the joints from the inside.

The ID is 24". 12" height. 13.5" width doorway, roughly 7.5" inside arch height. I am hoping to make 10 or 12" pizzas with some embers still in the oven.

I wish I had used more bricks, more cuts and less Firestop. I had to use just over 50# and did have to purchase another bag. However I did waste a lot, for example I made more than was necessary for 1 course and had been doing only 1 course per day. I think 50# would be plenty in retrospect.

It's not too pretty but unfortunately that is me. Hopefully after the blanket insulation I will bring in my wife for the final decoration which will cover up all of my ugliness.

I am thinking I will not touch it for a full week, other than to keep it moist... and then do slow fire ups after that. I haven't figured out if I should fire it up with the insulation, without, or if it does not matter.:confused:

Also I will have to change that cap to a spark arrestor.

staestc 10-23-2008 02:54 PM

Re: Form for 24" ?
Well, I for one am impressed! In less time than I have been plotting and scheming to build an oven and outdoor kitchen, you have an oven! :D :o

I would let it cure for a week or so to get some of the moisture out of the mortar, then do the small fire cures to help get some of the rest of the moisture out, then go from there.


pjcampo 10-23-2008 02:59 PM

Re: Form for 24" ?
I have posts on here from over a year ago... so I was at least dreaming about it back then!!!

I did pour the form for the slab in the Spring. The foundation and 3 sides made out of stone were leftover from an old outdoor grill that came with the house.

I ordered the floor insulation and cut it a month ago or so.

But the first time mortar went to brick was 1 week ago tomorrow. :D

It will still be a process until it's truly done done but I feel relieved that the dome is formed!!!!

Thanks for the comments and good luck with yours!

dmun 10-23-2008 04:04 PM

Re: Form for 24" ?
Having the vent in the dome may prove to be a problem. With that small a dome, it may leak all your heat out, rather than concentrating it for pizza use. I'd leave the option to make a longer entry, and move the flue to that if you have problems getting and keeping temperature.

Looks good, BTW.

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