1st Post - Dome Mold Hack?

[bentedesco]

I've been lurking on this forum for a while now, and cannot thank you all enough for the wealth of knowledge you offer!!! I have finally decided to start my build, however, I've become fascinated with building a form for my 36" x 18" dome.

I was planning on just piling dirt into a 36"x18" form but question whether or not this would hold or if I might get a lopsided/collapsed dome!

As I was thinking about this, I realized that a 36" beach ball could be cut in half to precisely the size I need for my inner dome. I'm wondering if any of you have tried filling a beach ball with *something* that would expand into a solid form (And then cut the ball in half) or coating the outside of a beach-ball with *Something* hard that then we could use as a form to stack my bricks around when building the dome?

Right now, the only idea that I have is using spray foam insulation into a beach ball, letting that harden, and then cutting the foam ball in half.

Thoughts?

[UtahBeehiver]

I would like to suggest you review the cheap eplans from our wed host Forno Bravo, they are downloadable and only a few bucks. It will give you a good baseline on the operation and construction of a pizza oven. I am assuming you are talking about a 1/2 of 36" sphere when you mean 36" x 18" dome. There are several ways to accomplish this, sand mold, beach ball has been used but questionable of how well it works, inner segment forms, etc. Again, I suggest you review the eplans and go from there.

[fox]

A pile of shaped sand covered in damp news paper is popular, I don’t think you ball idea will work because a 36” ball is only 36” when inflated under pressure. When not inflated it will probably only be 24” ?
I built a mould around a 32” silicon exercise ball, one thing I discovered is it was far from being symmetrical or round.
However you could use an inflated ball by cutting a 36” hole in a sheet of ply and just working on the exposed top half.
The problem with that is you really need to build the dome in situation because it is going to weigh a lot!

[bentedesco]

A pile of shaped sand covered in damp news paper is popular, I don’t think you ball idea will work because a 36” ball is only 36” when inflated under pressure. When not inflated it will probably only be 24” ?
I built a mould around a 32” silicon exercise ball, one thing I discovered is it was far from being symmetrical or round.
However you could use an inflated ball by cutting a 36” hole in a sheet of ply and just working on the exposed top half.
The problem with that is you really need to build the dome in situation because it is going to weigh a lot!

Thanks Fox, that makes great sense!

[Doodney]

bark & sand to finish

[Doodney]

[bentedesco]

Doodney

The Woodchips are a GREAT idea!! That way you don't need to spend days digging sand out!