starting the dome

[cecilB]

What's the best way to start the dome - I see some people use a styrofoam form, and some use that neat thingie on the lazy susan (indispensible tool).
Finally we are getting somewhere, but now I have a new hand in this and he does have experience in brick laying, and carpentry - lots of it, I would say. but not in dome building.
Do you have to have a form to support the rings as you go - he says you can't just have one form. But I wonder because I see people using the "indispensible tool" and that holds only one brick in place and you move it to the next, right?

A friend is coming over this evening to work on it and thinks he'll get a few rings up - payment is dinner.
c

[Neil2]

Re: starting the dome

The first few rings go up pretty well without support. The top rings usually require some support. The forms also help you hold the shape as you go.

I, personally, recommend the Styrofoam "fan shaped" form. Use the cheapest 1/2 inch foam you can buy. Make a template out of ply or heavy cardboard for the cross section of the dome. Use the template to cut out the first foam cross section, then using the template, cut out foam "half" leaves. You will have to trim back the inside "spine"edge an inch or so that it will fit in a ring about the center. I used 12 "half leaves" for my 40 inch oven.

Place your soldier course then start erecting the fan. It will wedge in tightly inside the soldier course bricks. I used duct tape to hold the center and top of the fan together. I also got a bundle of cheap chopsticks - sometime the ends of a particular brick are not supported on the fan and I used the sticks to bridge across the foam.

One other thing I did was to cut a 6 inch "mouse door" in each fan to aid internal circulation and to be able to reach in to retrieve dropped tools

[jmhepworth]

Re: starting the dome

I found that I was able to build the whole thing without any support, using Ken's knotted string method to keep it more or less round. That won't result in the perfect shape that the indispensable tool gives, but it still works. The upper courses just required a bit more holding in place for a minute or so until they didn't slip. As I finished each course I was sure the next one would require some support, but I never had to. I was using Heat Stop 50, so I can't say whether I would have had the same success with other mortar. The down side with using a form is that it's harder to clean as you go. The form gets in the way. I was pretty messy and would have had a lot more mortar on the inside if I didn't clean as I went. And it is really hard to clean the inside while lying on your back in a humid oven soaking up heat from the sun. If I had it to do over again (and I may do another one some day), I would try to get an indispensable tool and be more careful cleaning as I went. But the knotted string method works, and the pizza tastes just as good with a less than perfect oven.

Joe

[RTflorida]

Re: starting the dome

I'm with Joe, forms are not a necessity for the first 9 or 10 courses. Heastop 50 really sticks pretty good, simply hold each brick in place for about 10 seconds and they don't slip.
I simply used 1 fin cut from 1/2" plywood propped up by a brick (so I could let it drop and pull it out when done) to check every 3rd or 4th brick to keep my height. FAR from a precision instrument, but my interior height came out to be exactly the 18" I planned.
If you are patient and good at the "eyeball" method, you don't need any forms or "indespensible tools" at all.

RT

[lwood]

Re: starting the dome

I am just about to get started on my dome and trying to figure out how I'm going to do it. Leaning toward a simple arc of 1/4' ply and an adjustable foot along the arc. Keep in mind I have access to very little here in the Philippine province. The local masons can do amazing things with forms. I'm sure they will have their own ideas about how to do the dome. Will post soon on how it turns out.

[ThisOldGarageNJ]

Re: starting the dome

I used a florm out of scrap 1/2 inch plywood, I call it a florm because I did the floor shape with it for the soldier course then built the arches to it. I cut the ribs on the band saw, Had a pretty good amount of room to work inside. The pics wil be more self explanatory,, And to get it out, I used fire, Worked fine,,,,,
Mark

[cecilB]

Re: starting the dome

Thankyou everyone -
We went ahead and made forms out of the styrofoam. We're using the homebrew for the mortar.
But we only got as far as the sides of the opening...
Cecelia