~38" build in Seattle

[UtahBeehiver]

Re: ~38" build in Seattle

One more pic from my build showing how the IT helps set the intersect between the arch and dome arc.

[Gulf]

Re: ~38" build in Seattle

I came in for a break and saw your reply. I went back out for a test on the brick that I have. I took one of my old trials and was able to half one of them with two strikes on one side. I did the same test on a medium density firebrick left over from my dome. I pretty much had to mark it all the way around, three strikes each, before it broke. I was easily able scratch a 1/4" trench in the old brick of mine with a the claw end of a hammer. The medium duty firebrick just sharpened the claw.

[brickie in oz]

Re: ~38" build in Seattle

Any other advice before I start mixing mortar?

Your arch profile is too far forwards, you will end up with a tear drop shaped roof in the oven. ( the oven will still work ok though)
Try moving the profile back into the oven more.

[pluscwc]

Re: ~38" build in Seattle

I came in for a break and saw your reply. I went back out for a test on the brick that I have. I took one of my old trials and was able to half one of them with two strikes on one side. I did the same test on a medium density firebrick left over from my dome. I pretty much had to mark it all the way around, three strikes each, before it broke. I was easily able scratch a 1/4" trench in the old brick of mine with a the claw end of a hammer. The medium duty firebrick just sharpened the claw.

You apparently have better firebrick than up here in the Pacific Northwest. I could scratch a thin track in both types of brick with the corner of a claw hammer. It was easier to split the standard firebrick than my mysterious firebrick-like substance.

I took a MAPP torch to one side of a sample brick, but I didn't want to deal with how long it would take to get up to temperature, since I don't have a thermometer than can read high enough. Maybe next time I fire up the grill, I'll through one in.

[pluscwc]

Re: ~38" build in Seattle

Your arch profile is too far forwards, you will end up with a tear drop shaped roof in the oven. ( the oven will still work ok though)
Try moving the profile back into the oven more.

I don't understand that. The shape of the roof of the oven should be defined by the IT and if I make each run level or not. Or how else I screw things up.

My arch template is defining the forward edge of the arch. The back edge(s) of the arch is defined by the IT. Looking at the arch brick, these are the two rightmost faces. The upper face should be radial from the center point, the lower face should be perpendicular to that one, in the same plane as the inside of the oven. I can change where that is a little bit, but if I push it further back into the oven, I will need to make the arch taller to get it tangent with the interior of the dome. Without changing the template height, I can move the template back only as far as the bottom of the piece currently shown, which does nothing to the arch or dome geometry. It's just an artifact of having a template that is too thin.

[pluscwc]

Re: ~38" build in Seattle

By the way, thank you to everyone who's offered help and advice so far. I hope my oven comes out marginally close to the quality builds I watched y'all do.

I'm nervous about actually committing to mortaring bricks together. Even knowing it's going to work out, it's tough to just jump in with zero first hand experience and a few years of reading these threads.

[mrchipster]

Re: ~38" build in Seattle

I don't understand that. The shape of the roof of the oven should be defined by the IT and if I make each run level or not. Or how else I screw things up.

My arch template is defining the forward edge of the arch. The back edge(s) of the arch is defined by the IT. Looking at the arch brick, these are the two rightmost faces. The upper face should be radial from the center point, the lower face should be perpendicular to that one, in the same plane as the inside of the oven. I can change where that is a little bit, but if I push it further back into the oven, I will need to make the arch taller to get it tangent with the interior of the dome. Without changing the template height, I can move the template back only as far as the bottom of the piece currently shown, which does nothing to the arch or dome geometry. It's just an artifact of having a template that is too thin.

I posted this before but it sometimes requires repeating.

The key for me in understanding this type of inner arch design was to understand that the slope of the cutoff for the top of the inner arch (the cut that will receive the dome bricks) is defined by the inner radius of the dome -- lower edge of brick, the outer radius of the dome - upper edge of brick, and the slope of the cut, as a vector from the center of the oven.

This works for straight sided openings as well as circular. You need to check alignment of all of the bricks in the arch if it is hemispherical as the shape starts at the first course.

[pluscwc]

Re: ~38" build in Seattle

I posted this before but it sometimes requires repeating.

The key for me in understanding this type of inner arch design was to understand that the slope of the cutoff for the top of the inner arch (the cut that will receive the dome bricks) is defined by the inner radius of the dome -- lower edge of brick, the outer radius of the dome - upper edge of brick, and the slope of the cut, as a vector from the center of the oven.

This works for straight sided openings as well as circular. You need to check alignment of all of the bricks in the arch if it is hemispherical as the shap starts at the first course.

I think you said it better than me, but that is what I was trying to say. One exception I would take is that the upper edge of the brick doesn't need to be the outer surface of the dome, but the other two variables, slope and lower edge are important.

Got almost all the soldiers mortared in today. Need to cut a half size piece to finish, but I had run out of mortar.
Also built a PVC tarp tent so I can hopefully be ok when it rains next. No pictures since it's dark.
Next up, testing out my brick jig and deejayoh's spreadsheet.

[mrchipster]

Re: ~38" build in Seattle

I think you said it better than me, but that is what I was trying to say. One exception I would take is that the upper edge of the brick doesn't need to be the outer surface of the dome, but the other two variables, slope and lower edge are important.
.

I agree that the upper edge does not to be the outer surface of the dome but that location is important, the brick needs at least that amount of surface available for the dome bricks to seat on. If the arch brick surface is not cut back at least that far or that much material is provided there will not be enough surface to maintain a uniform thickness of brick.

[pluscwc]

Re: ~38" build in Seattle

I'd like anyone to know that I'm still in the running for taking the longest possible to build an oven. 3.5 years so far since the foundation was poured. SWMBO finally said it was an eyesore and I needed to get it functioning this year.

The progress for the last month. Up to row 8 out of 10, so the dome should be closing up soon. I used deejayoh's spreadsheet for the first 4 rows, something was off on row four and so I started just cutting to fit based on a good guess to start with and adjustments to individual bricks to compensate for non-roundness.

I'm not super happy with my IT, it has too many degrees of freedom. I should have epoxied the threaded rod into the caster to keep it from occasionally pulling out.

For anyone interested in the effects of taking too long, FB board will mildew if left wet over the winter.

Paper bags of sand and fireclay have their bottoms rot out over similar winter if left on the ground.

[pluscwc]

Re: ~38" build in Seattle

Because of my oven's location immediately next to what we call the cooking cover, I need to have an extra tall chimney. Ouch, that's going to be expensive.

The peak of the cooking cover is ~13 feet high, so if the chimney starts at what, 6 feet, I'll need at least 9 feet of chimney pipe?

Can I use a smaller diameter pipe because the extra length will help with draw? 6" ID will certainly be less imposing than 8" ID pipe.

Also, what are good sources for heartbreak caulking and stuffing if I go that route?

[Greenman]

Re: ~38" build in Seattle

"Also, what are good sources for heartbreak caulking and stuffing if I go that route?"

Excuse my mirth but that sounds like a Freudian slip from an oven builder who has been put under 'completion pressure'.

You have done most of the hard work and one more push will put you in a good place. All the best with completing.

[pluscwc]

Re: ~38" build in Seattle

ahem, oops. ...heatbreak... yeah, that's what I meant.

[deejayoh]

Re: ~38" build in Seattle

You're over the arch, that's great! Easier to build from there on out.

Not sure about your flue question - I think there is a thread on here somewhere with a height/diameter tradeoff chart.

I ordered my caulk from a metalworking shop down in oregon. Cant remember the name but I know it's in my thread somewhere. Prices were good, but service was slow.

[pluscwc]

Re: ~38" build in Seattle

Found it in your thread. Was this the material you stuffed into the gap? Kiln Gasket - Flat

How many tubes of caulk did you need?

I found http://www.fornobravo.com/forum/f28/...ator-3905.html which if it is to be believed shows similar performance from a 3 meter 6" pipe and a 1 meter 8" pipe. Question becomes would I be better off with the 3 meter 8" pipe and even more airflow.