tapered soldier course?

[Dutchoven]

Don't know if anyone has already done this but, I am preparing to build an oven with/for friends and I had this as an idea. The soldier course would be composed of 2.3 x 4.5 x 9 inch firebrick halved with a half inch taper. 4 inches on the inside and 5 inches on the outside. In theory it seems to spring the dome quite well.
I look forward to relplies!
Best
Dutch

[RTflorida]

Dutch, thats how I did mine. My firebricks are what is called 'wire cut'; so they were not consistant in width and length (roughly 4 1/4 x 8 3/4). For the soldiers, I trimmed about 1/16 off the bottoms to square them up then cut the inside height at 3 1/2 and the ouside at 4 1/2.....same concept your planning.

I found this approach was the only way to achieve and 18" height for my 36" oven...keeping my mortar joints (on the outside) at 1/4" or less, which was my goal. Worked out perfectly, gives you a great spring affect into the curve. From an engineering standpoint; I would not taper them any more, it could lead to an outward thrust problem (colapse?)

You should be more than fine with what you plan; my dome has been complete for almost 8 wks with at least a dozen 'scary' fires (and many smaller fires) since curring; and only 1 crack (mortar joint on the entry arch).
Good luck.

RT

[dmun]

It's great that you could find "red" firebricks, I think they look so much better than the beige ones. I could only find one place to get them here in Jersey. Good luck with your project.

[RTflorida]

Some color, any color, would have been nice for me. Only 2 suppliers stocked firebrick in my area (both had cream colored). The refractory specialist offered to order tan or brown in medium duty ($2.60 per brick).

I opted for one of the lovely cream hues from a masonry supplier (light duty and only 70 cents per brick)

[james]

Nice idea on cutting the first course. It seems as through there are three options:

1. Cut the angle on the first course.
2. Cut an angled wedge as the second course
3. Don't make a cut, and use a wedge and mortar to set the inward angle.

There is a thread on how to angle and cut the second course bricks here:

http://www.fornobravo.com/forum/f8/p...sign-1843.html (A Potential New Low Dome Design)

What is the general consensus on this? I think this is an important topic, and we probably want to get this into the standard plans and e-book pretty soon so that new builders can see the options before they start.
James

[wlively]

Originally Posted by james

Nice idea on cutting the first course. It seems as through there are three options:

1. Cut the angle on the first course.
2. Cut an angled wedge as the second course
3. Don't make a cut, and use a wedge and mortar to set the inward angle.

What is the general consensus on this? I think this is an important topic, and we probably want to get this into the standard plans and e-book pretty soon so that new builders can see the options before they start.
James

Agree, those seem to be the options. I found that while most of my bricks were pretty much the same general dimensions. They were definitely not standard enough to cut 1 inch off of one side and have them all be equal height. That is why I went with the KISS method. Wedge and mortar.

[Dutchoven]

Having done this as a mock up, one also has to consider accuracy of cut and saw blade width on the cut. I cut these with a diamond blade on a circular saw, not a wet saw, so it was very tricky and they are not all perfect. Also you really can't just score and pop them either, without having to grind them smooth. I experimented with both methods. I think with a wetsaw and a jig one could make these cuts quite accurately and, Wade although I agree 100% with your concern of irregularites, with a bit of attention by the builder to the selection of the bricks for this soldier course I think the benefits could out weigh the challenges.

RT the bricks I have set as door posts(temporarily) were my original cut for the spring course and were 3 inches intrados 6 inches extrados. I had concerns about thrust when I looked at the shape of the dome with those and I plan on seeing how it looks with even a smaller taper. When I did the math it was about .55 inches on 4.5 inches to achieve an approximately 7 to 8 degree tilt.

It also seems when you make this taper near the center of the brick, as opposed to closer to the end, the dome has a very stable shape. This taper keeps brick counts similar as it is still a cut exactly(tongue in cheek) in half.

As far as the color, when I bought just these few brick(20 or so it was) the supplier was concerned that she didn't have the "buff" color and apologized saying she only had red. I also like the red, my wife seems to like the idea of the buff, expecially for the floor. These are standard duty and cost me .89 per in that small quantity.

I am really happy I started this topic as I think we have a lot of great thinkers here on the forum and this could be something that might help newbies.
All the best!
Dutch

[Archena]

Originally Posted by Dutchoven

Don't know if anyone has already done this but, I am preparing to build an oven with/for friends and I had this as an idea. The soldier course would be composed of 2.3 x 4.5 x 9 inch firebrick halved with a half inch taper. 4 inches on the inside and 5 inches on the outside. In theory it seems to spring the dome quite well.
I look forward to relplies!
Best
Dutch

Someone posted link to a series of photos from a workshop where it looks like they did just that. I'll see if I can find it.

[wlively]

Dutch

Sorry, I did not comment on your method. I hope that did not imply that it was not a good option. Given that the structure only needs to be self-supporting, all three methods will work.

Your angle cut looks good and I am sure it will work beautifully. It should make setting the initial angle easy and will save $$ in mortar as well.

There are masonry artists that create gorgeous domes, and then there are the others, like me, who just want to eat pizza.

[Archena]

Here's the link I mentioned: MHA News - 2006 Meeting - Backyard Oven with Peter Moore

It was originally posted by Gaptogap. Ignore the stand - Gap says the whole thing was taken down after the workshop.

Also, it's a huge file so dial-up beware! Took me forever to download it.