Alternating Partial-Taper brick construction?

[Artichoke]

Hi all,
This is my first submission to the forum. I am planning my Pompeii oven for a firing in the spring. There is a lot of great information on the construction of domes on this site thank you. While I was planning my project I started making a model of the brick dome in Sketchup, Which I use for my woodworking projects.

In looking through the threads I became very interested in tapering the bricks to affect an internal dome with minimal grout gaps. Very nice. There are some wonderful threads including:

http://www.fornobravo.com/forum/f28/...idea-2573.html (Hendo's dome gauge -- nice idea)
http://www.fornobravo.com/forum/f28/...tilt-2802.html (Twist and Tilt)

While working my model on the computer with the idea of tapering bricks it struck me that I could try two things.

1) Make the tapers large enough so that only on the front (internal dome) of the block is cut. I am removing only enough material to eliminate the small triangle created by two adjacent rectangular bricks (see image). Keeping the blocks as large as possible.

2)Only taper every other block in the course.One rectangular block one partial tapered block (see image). Seems like half the work to me.

The resulting dome is presented in the third attachment. You can notice the alternating rectangles and trapezoids but little grout seam.

I do have a question to those with experience building a dome. Is there any obvious problem with this approach especially in terms of structural problems?

Cheers

[mine]

Your needed gap sizes will be determined largely by your choice of mortar.

[Frances]

Looks good to me.

Come to think about it, I probably did about the same thing on my dome only in a more haphazard way - that should work out really well.

[Bandrasco]

Thats certainly an option but what you will use a lot of very expensive refractory mortar filling in the gaps. I went with the route of both bevel and taper since the fire bricks are cheap and the mortar is expensive. I've seen many builds like that and didn't hear of any not being structurally sound.

I like the drawing (cad?), that would be nice to look at prior to a build.

Good luck!

[christo]

I think we've found our forum Google Sketchup expert!!!

If you're planning on using the homemade mortar mix, I think that design will result in a good looking oven that is cost effective and minimizes cuts.

You might consider using a mix of the homemade mortar (fill in large gaps on outside of dome) and the refrax type mix on the tight joints (butt and side to side) and come to think of it - maybe the first ring, too. I think egalecki filled the large joints on her oven with a pastry bag or mortar bag.

Christo

[dmun]

This reminds me of an idea I once had to taper every other brick, to approach the full cut dome:




This provides a lower mortar usage, with a lot less work than cutting every brick into a full cut wedge. I was reminded of it because of your alternating cut and straight bricks.

[Frances]

I knew someone had posted something similar! Might have known it was you , dmun

[Artichoke]

Gruetzi Frances,
Allschwil near Basel? Nice location, I used to live in Zurich (for about 5 years) actually my wife is currently in Basel for a couple of days giving a talk.
Depending on how well I can build mine might look haphazard!

[Artichoke]

Thanks Bandrasco,
I must admit I was not thinking about the relative cost of bricks versus mortar. Good point. I was considering the time it takes to "precision" cut bricks. The alternating taper will at least reduce some mortar use?
Cheers
Joe

[Artichoke]

Christo,

I have not built anything with bricks other than fixing some dry paving in the back yard.Is it common to mix mortar types? Is it a problem to add another thermal expansion variable to the dome? What is the relative cost of the home brew relative to refrax?
Cheers
Joe