Round shape

[Mike D]

Re: Round shape

Thanks guys,

And yes the arch should have been pushed back farther into the dome. I figured this out a little too late. I posted this a few posts back and put my findings in a new thread called "teardrop". Read the tread and put your 2 cents in to help others avoid this problem. I don't think this is in the plans at all, which is why I started the thread. I think it should be a sticky (but that's just me).

It's not so much of a dip down into the arch as it is a reach to connect to the arch. Here is a pic showing that the sides are almost level with the top of the arch. I am not so much embarrassed, but just looking for any ideas to correct for it as possible.

Dino, I too was thinking about putting a whole brick across the top to help round in the area by the arch. I'll have to see how it fits. What did you mean about the sharper tapers on the bottom? As in more of a tilt?

Mike

[GianniFocaccia]

Re: Round shape

Mike,

I agree, this should be a sticky since I struggled with this in the design phase for way too long. I ultimately refined a model in SketchUp that I was happy with and followed my plan.

In optimizing the distance from the oven center to the outer face of the arch I had two requirements: 1)the inside profile of the arch had to match the interior curvature of the dome to eliminate me having to 'hang' any angled dome bricks against an interior arch vertical surface, and 2) the arch itself had to extend forward enough to clear the outside perimeter of the dome. Because this extended dimension required a brick that was 4.5"x 5.25", I was not able to use half-bricks.

Once I plugged my arch dimensions into SketchUp, (20"W x 12"H I.D. or 29"W x 16.5"H O.D., the dimensions just worked themselves out. Note: I wasn't sure if it would actually occur, but I believe (since I'm not an engineer) a number of efficiencies resulted from a hemispherical arch design: The curve of the arch where it meets the dome seems more symmetrical than the more popular linear (vertical) entryway arches. Also, the hemi-arch may be a tad bit stronger than the traditional vertical-sided arch since it is integrated into the dome, but who knows?

My original design called for vertical planes (soldiers and vertical-sided entryway) but after learning about side thrust forces (and the need for buttressing), I decided to try to engineer these out of the arch, entryway, and dome itself.

My two cents worth,

John

[Lburou]

Re: Round shape

GianniFocaccia (John)

One thing worth mentioning that helped clean up your arch/dome transition is the angle cut on the dome side of your inner arch bricks. Although there may be other people using this angled transition, you, Karangi Dude and Sharkey are the only three builders I have seen using that trick.

Karangi Dude's inner arch:

GianniFocaccia's inner arch:

Also in Sharkey's inner arch.

[Dino_Pizza]

Re: Round shape

Mike, I just meant a sharper tilt IF NEEDED to get to your final dome height. Since I was building a 42" diameter oven, I thought keeping my dome height at 19-20" instead of 21" was a good goal (not officially a low dome, just a bit flatter). I ended up just over 20" and it's tough fighting gravity until you wedge in that keystone.

Those pics that LeeB showed show you could take a grinder to the sharp edges at the very top of your inner arch to make it flatter for the brick to span it. Just a thought. Many say keep the grinder as far away from your oven as possible but I used it so much leveling some rows that I got good at it, but it's always dangerous: you can't put it back after grinding it out .

You and Gianni-John have 2 of the nicest arches on the forum.

-Dino

[Mike D]

Re: Round shape

Thanks Dino,

I am still on track for my dome height about 19", and yes the tilt is getting steeper, the pictures never give you a true perspective of the angles.

The grinder is nice, but I don't want to get it close to my dome if I don't have to. If it's on the dome, I don't want to vibrate anything loose.

Mike

[dmun]

Re: Round shape


This drawing illustrates something that most builders don't think about until they get a few courses up: Either the entry goes into the dome, or the dome gets ellongated (teardrop shape) as you stretch to meet the entry. It has to do with the intersection of a sphere and a cylinder: it's not really linear.

[SableSprings]

Re: Round shape

I built a 39" Pompeii style dome (actually with more of a beaver tail hearth) using standard firebricks and perlite/cement insulation. I also wanted the exterior look of brick instead of the "gray" perlcrete, so I cut bricks length-wise and created a barrel vault false exterior over my "roundish" oven. Check either my Dragonfly Den photo link at the bottom of www.sablesprings.com or in Forno Bravo albums (The Dragonfly Den, posted by SableSprings) to see the result. Since my brick facade rests on the concrete platform outside the actual oven footprint-not on my underlying perlcrete hearth insulation-I don't have any worries with the additional weight.

[Mike D]

Re: Round shape

Thanks every one for the support-

You should put these pics in the other thread "teardrop" to help others when they are starting out. I don't remember seeing anything about this in the plans. It could go in the oven opening thread or the recommended changes thread.

Mike

[brickie in oz]

Re: Round shape

"teardrop"

Would mean nothing to a newbie, it should be titled, Building Mistakes to Avoid, or something

[Lburou]

Re: Round shape

Would mean nothing to a newbie, it should be titled, Building Mistakes to Avoid, or something

I like that oven because it does not have the quirky chimney usually associated with the beavertail and because you can see the entire oven floor easily, not to mention the easier cleaning than the more common round floor with hidden spots. There are several more unique and desirable add-ons to the dragon fly den if you look closely

Sorry to have hijacked your thread

[brickie in oz]

Re: Round shape

Personally I dont see a problem with the teardrop effect apart from a construction point of view which with some construction building knowledge is easily overcome.
I just love the look of ovens built outside of the "normal" expectations with all their quirks and faults, bring them on.

As long as the cook who cares?

[gdest]

Re: Round shape

Well when I looked at mine from above, I thought it looked more like a heat shape. Everyone else said it looked like a lemon!! lol So much for my friends

Gary (from Saudi)

[Sharkey]

Re: Round shape

GianniFocaccia (John)

One thing worth mentioning that helped clean up your arch/dome transition is the angle cut on the dome side of your inner arch bricks. Although there may be other people using this angled transition, you, Karangi Dude and Sharkey are the only three builders I have seen using that trick.

Karangi Dude's inner arch:

But not only can you angle the arch brick to make the transition with the dome easier, you can also make the arch bricks longer as you climb up the arch to avoid the teardrop.

You can see Karangi Dude has done this in the photo above. At the bottom of his arch the brick is only an inch or so before it angles for the transition. At the top of the arch you can see it is a good four inches or more.

You can also see it on my oven in this photo. The arch bricks are deeper at the top of the arch than they are at the bottom:


It is this extra length in the arch bricks that avoids the teardrop. You can use your dome tool to work out where the inside of the arch needs to be and also the angles.

Sharkey

[Mike D]

Re: Round shape

-This looks nice, but this arch reaches to get to the dome, rather than the dome reaching to get to the Arch.

-All I am saying is just push your Arch farther into the dome so you wouldn't have this problem. I could not see this problem until it was too late. If this was only mentioned in one of the threads it would be helpful. Maybe in the arch size thread?
Mike

[brickie in oz]

Re: Round shape

It would not make much difference how far you push the arch into the dome at some stage you will have the same problem,

It makes all the difference as to where your arch is positioned and how high your arch is.
Maybe you fluked it, but positioning and size make all the difference to an easy build.