How high to start curve of entry arch?

[jimkramer]

I was originally going to make a straight entrance, with angle iron across the top. I've been convinced by my brothers in ovens to not do this, and make an arch, as it seems the heating/cooling can degrade the iron over the years.

So...a this point, the bricks on the side of my opening are straight, up to a height of 9.5" (I started with a course of splits). I think (without checking the plans) that the ovening is supposed to be 12.5". So I'll have to take out a brick or two to create an arch that doesn't go over 12.5".

The question is: how high up can I start the curve of the arch? It seems some people start the curve on the second brick, some lay a couple down flat, then start the arch. I'd prefer to take out as few as possible.

[Tscarborough]

Re: How high to start curve of entry arch?

You can make a shallow arch work as you have it. Here is one:

[deejayoh]

Re: How high to start curve of entry arch?

bunch of comments for you

1. rather than starting a new thread for each question you have - I suggest you ask them on your "Build for the common man" thread. Everybody who has commented there is subscribed and will see your questions - makes it easier to follow along and review relevant details like...
2. ...the size of your oven. Your arch height should be ~63% of your dome height. So if your dome is going to be 20-21 inches high, you should be fine building a shallow arch. You may need to buttress your entry to make it strong enough
3. Looking at your picture, I don't think your IT is designed correctly. The center of the pivot arm needs to hit the center of the brick course. Yours is set up so that it's hitting about 1/2" from the top of the brick. What will happen is that each course will be off axis a bit the courses will be staggered back by a bit. you need to put a spacer between the pivot arm and the wood that hits the top of your brick so that the center of the arm is @ 1.25" from the top of the brick.

[deejayoh]

Re: How high to start curve of entry arch?

On the IT - here's a picture of the problem I see


And the solution


Pictures gratuitously stolen from other threads and posters

[jimkramer]

Re: How high to start curve of entry arch?

Tscar-
Thanks for the shallow arch shot. I Very glad to hear I don't have to knock out lots of bricks to do it. Whose build is that from?

Deejayoh-

You can't see it in the other picture I posted, but the second piece of wood slides on top of the lower piece to make it adjustable, and then there's a metal bracket at the end, to hold the brick. I think you can see it better in this pic. I'll check again, but I'm pretty sure the center of the brick is in line with the pivot point. Please check this pic to see if it looks okay, as I'm very glad to have many second sets of eyes out there.

I'll try posting future questions in my build thread, to see how it goes. I just figured more would see my question if I posted it separately.

[Tscarborough]

Re: How high to start curve of entry arch?

Here is a better pic of it. It is an oven I built for a friend.

[Tscarborough]

Re: How high to start curve of entry arch?

Note that it is buttressed, both by the concrete band and the pilasters, because that is required for a shallow arch.

[deejayoh]

Re: How high to start curve of entry arch?

Deejayoh-

You can't see it in the other picture I posted, but the second piece of wood slides on top of the lower piece to make it adjustable, and then there's a metal bracket at the end, to hold the brick. I think you can see it better in this pic. I'll check again, but I'm pretty sure the center of the brick is in line with the pivot point. Please check this pic to see if it looks okay, as I'm very glad to have many second sets of eyes out there.

Ah, I could not see that bracket - looks great. I've seen a few of the other types of IT so just commented to be on the safe side.

[stonecutter]

Re: How high to start curve of entry arch?

Here is a better pic of it. It is an oven I built for a friend.

Layout solution :

Four corners on the left of the entry floor is off pattern to avoid a small triangle on the outside corner.