Using balls inside oven during construction

[Davy]

I have built my oven, two courses to go, using a 34" ball for courses 7, 8 and 9, then a 24" ball for courses 10, 11, 12 and the last bricks. It has worked very well. With each additional course I would adjust the pressure in the ball, either up or down, to fit the bricks. Where the circle of bricks was a little out of "round" I would adjust by using wedges.

I would recommend this method to anyone starting out with their construction.

Ciao for now,
Davy

[stuart]

Looks good, any finished photos, especially a profile showing the final shape?

[Marcel]

Canadians have an unfair advantage

(M) Well, Davy, now that I see you live in Canada that explains your success. The clear cool air clarifies the mind and makes work easier than for your warmer southern neighbors.

(M) I wrote you privately about the previous disappearance of your photos and hope that these will remain, but I have some other serious questions:

(M) You wrote, in part:

(D) "using a 34" ball for courses 7, 8 and 9, then a 24" ball for courses 10, 11, 12 and the last bricks."

(M) If you used a smaller ball for the last courses did it need to sit on a partly deflated 34" ball to reach the top? ____

(M) Did either ball expand significantly - noticeably beyond it's normal full circumference? ____

(M) Since your dome is essentially very close to a true hemisphere I would have assumed that one ball, the top half of which was close to the interior radius of your dome, e.g. 21" would have sufficed.

(M) I understand, of course that a ball is spherical and that only the top 1/2 would be helpful in supporting your bricks; the first few courses would not need any support. I tried ballons with my 8 vanes but had only limited success; but of course I only live in Oregon.

(M) I have many questions because my spatial visualization is poorly developed. Any clarification on how those balls responded to changes in internal air pressure might be helpful for others too. I'd also be curious to know the cost of each ball: $___

(M) Thanks for your time.

(M) P.S. Stuart, I think there is a good chance that Davy will post on PhotoBucket and if he chooses to make his images public, we may see far more than the 4 he's shared to date.

Ciao,

Marcel

[Davy]

Balls are easy to use

As marcel has noted I hope to put my 50+ photos of oven construction onto photobucket so all can see the stages I went through.

The first 6 courses of my 42" oven went up without having to have any inside support. In an earlier thread I espoused the virtues of not using wedges to get the right angle, but to use one's eye and a level instead. The wedges got in the way of putting in mortar. I found it easier to slather down a blob of mortar then put the brick on top and adjust it accordingly for angle.
The 7th course suffered greatly from gravity so needed a helping hand. I put the 34" ball (purchased at Toys R Us for $10) on the hearth and inflated it with my compressor until it came out far enough to support the 7th course. (The ball at this point was not fully inflated.) Because my 7th course was not perfectly spherical I had to use wedges here and there to support the brick between the brick and the ball. Apart from getting the angle more or less correct it was important to ensure the bottom edge of each brick was placed directly over the top edge of the underlying bricks.

For course 8 I had to deflate the ball slightly because the circle of bricks was obviously getting smaller. I just let a little air out and bingo!

Although I could probably have continued using the 34" ball I decided to switch to the 24" swedish gym ball. It was closer to the shape that I wanted and it was sturdier in construction than the bigger ball. (I didn't tell my wife what I was doing with her ball.) I found the gym ball better support than the big ball because the sides did not squish in when the weight of a brick was added, as happened with the 34" ball.

I have now ground to shape all the bricks needed for course 12, and just have to put some mortar around them. They will not need much mortar as they all fit tightly now. That will leave a "hole" in the top of the oven about
5" across at the bottom and 7" across at the top. I'm not sure yet how I will fill this hole.

I will post some more photos as soon as I have them.

Ciao for now,
Davy

[Davy]

12th course finished

I have just finished dry fitting course 12 after grinding each brick to fit snugly. When I was satisfied with the fit I then applied mortar. The attached photos show the dry fit stage then the mortared stage.

Just the key bricks to go and I'm done. I'm already starting to taste that pizza and imbibe with red wine. I'm feeling Italian so will end with ...

Ciao for now,
Davy

[Davy]

Oven construction photos at Photobucket

I think forum members can now view my oven photos at:
http://s74.photobucket.com/albums/i242/abpo/

If this works I will include all of my photos if anyone is interested in seeing them

Ciao for now,
Davy

[CanuckJim]

Fine Job

Davy,

Innovation, attention to detail and a willingness to take you time resulted in an excellent job. Congratulations. Marcel is correct, as mostly always, because we Canadians do have an unfair advantage. He marked it down to clear air, but we both know it's the beer, eh.

Jim