36" Pompeii Build in the desert

[jim lofaro]

My bad; posted the wrong front picture:

[Gulf]

If you haven't already, now is the time to use your IT to make sure. Set one of your brick top dead center ant make sure that the arch is not too far forward. It looked good on paper, but there is nothing like checking it in real life. It may also save you an inch for the landing.

[UtahBeehiver]

Second this suggestion. Remember the radius at the TDC will be different than at the base due to the offset of the pivot point from floor level. Could be somewhere up to an 1" longer at TDC.

[jim lofaro]

So I marked the inner/outer radii using a pencil placed in the IT and then added a 4.5 inch extension to get the outer radius (see attached). Then placed a brick at the TDC location and clamped a brick in the IT and got as close as I could to the TDC brick. Not sure what I am looking for that would determine if the form is in the right place or not (see attached). I noticed the plywood the IT is bolted to is warped so i am not absolutely sure how far the IT is off the floor.

[UtahBeehiver]

Once one side of the TDC is done it becomes the template for the adjacent brick and the IT set the angle for the far side of the adjacent brick. Also the TDC will be the longest brick so you could move the two intersecting angles (point) to the right about a 1/2" or so if you want. It is always good to have the arch protrude from the OD of the dome

[JRPizza]

. Not sure what I am looking for that would determine if the form is in the right place or not (see attached).

Jim, what you are looking for is to make sure that the TDC brick fits within the inner and outer shell of the oven, which it looks like yours does. What you can do now is wrap the first layer of the dome around and see how it will mate up with your arch like the attached picture. You can see I could have moved my arch back a little and had less protrusion at the front, but it was pretty much where I wanted it. Now is the time you can fine tune the position. I can't tell by your picture, but you do have the front edge of the brick flush with your form? The angle makes it hard to tell.

[Gulf]

While you are fine tuning there are a couple or so things that you may want to consider.

This may have been covered earlier in the thread, but I don't see any relief cuts in your plywood floor. If not corrected, it will be very difficult to remove.

I also seem to remember you saying that your plywood base was "warped". I too, had that problem. While dry stacking my arch I found that the IT would move when I stepped on the floor. I did not like the anchor point for my IT being unstable. So, I removed the center brick from the floor and replaced it with a temporary wooden brick to attach the IT. I'm glad that I did. Due to my short arms I had to step on that floor many times during the early part of the dome work. I used cardboard and later on some loose sand to protect the brick floor during construction.

The one thing that you will definitely want to do is shim the inner arch form so that you can remove it easily without disturbing the brick work.

[UtahBeehiver]

Joe, good catch on the relief cuts.

[jim lofaro]

Thanks all. Keep the cards and letters coming in.

JR; the brick at TDC was lined up at the front of the form.

Thanks Joe for the advice about the relief cuts and the center brick. Let me see how hard it is to remove mine.

A note about the arch form. It is actually wider than 4 ½ inches (see photo). I have been lining up the front of the form to match the location of the outside of the inner arch. When I start to add mortar to brick my plan is to have the inner arch form flush with the interior allowing the arch bricks to extend over the form and into the dome proper. Any thoughts?

What I did for the photo in post 64 was to align the top of the TDC brick with the top of the IT brick and draw the black line at the contact between the two (see the sketch in post 55). This should represent the outer dome radius (as I understand it). I also put a black tick mark where the face of the IT brick contacts the IT. Russell drew a red line extending downward. I am thinking that the red line is normal to the outer dome radius line (see photo)?

If I read Russell’s post 65 correctly I could create a jig based on the angle drawn on the TDC brick and translate that angle to the other arch bricks by moving the jig to the right ~ ½ inch (see photo). Does this sound right?

[jim lofaro]

removing the center floor brick was easier than i thought it would be.

[UtahBeehiver]

The red line I marked is the ID dome curvature. If you look at the hemisphere picture I sent you will see that the angles are skewed and are not identical from one side to the other.

[JRPizza]

The other thing Joe's "wooden brick" does for you is get the pivot point of your IT closer to the level of the floor, making the dome more of a perfect hemisphere. Also, like Russell said, the bricks for the arch will all have slightly different angles, so I don't think a template would work. I think most all of my cuts were "custom".

[jim lofaro]

Again, many thanks to all. Let me give the arch cuts a bit of a think. This is really tough on the old googootz.

[jim lofaro]

Note to self; JR post 28:

{{{

I finished off my second course and incorporated the first of my tapered arch bricks. Got about 1/3 of course 3 before I ran out of mortar and daylight. The joint thickness on the arch bricks is a little thicker than I wanted so will have to keep an eye on that. Ran into a little confidence crisis on cutting the back angles on my arch bricks, but UtahBeehiver has been helping me through the visualization and I think I am on the right track. That is one of the great things about this forum - knowledgeable people that are willing to help. Having someone to talk things through seems to really stimulate the thinking process. I had to put my marker back in the IT and trace the outline of inner and outer surface of the dome on my arch bricks. I saw this in UtahBeehiver picture gallery, but needed a little help understanding how it all fit together. I clamped a brick in the IT and brought it up next to my TDC arch brick, aligned it with the inner and outer marks, and established the angle needed for the brick to seat. I have no idea whether it will be a full width brick or a sliver when I incorporate the last course into my arch, but I have a good feel on how it will sit. I will use those marks I made on the balance of the arch bricks to cut them to shape as I build up.

}}}

[jim lofaro]

So first off let me apologize ahead of time for being so obtuse on these inner arch angles but…. Is there a written procedure in someone’s post I can read over?