Tapir Force Steps up to the plate!

[Lburou]

Re: Tapir Force Steps up to the plate!

Robert

Uncommonly good start!

I get your point about the sub floor not touching anything to transmit heat, but I see no value added to extending the sub floor out that far, in fact I agree with the guy with that Italian name

Its not too late, consider reigning the sub floor in a bit and I think you will be better in the long run for cooking temperatures 72 hours out from cooking pizza.

[GianniFocaccia]

Re: Tapir Force Steps up to the plate!

Ha! No way a screen name can compare to a warm-blooded red head named Lugina!
If I had a do-over I think I'd pick a screen name that was easy and real short, like: Mo Betta or something.

Practically speaking, cost of the firebricks aside, each time you fire your oven you will be heating 'external dome floor' that you can't use, except as a Quasimodo heat sink. Further, this wing-like structure, while nicely insulated may act as a cooling fin, spreading out the exposed cooling area instead of neatly tucked under the oven itself. I believe the rate of heat loss may exceed the conduction of stored energy back into the dome as usable heat. Of course I'm not a heat-transfer specialist like my late father-in-law was, but I did stay in Holiday Inn once.
John

[Tapir Force]

Re: Tapir Force Steps up to the plate!

This is of course why I signed up to share my build on this forum. I will in fact be trimming back my perfectly flat, uncommonly neat, and lovingly placed floor. As some have noted, I am going at this thing with fervor. I have some big greenhouse projects in front of me and I want this thing (at least the dome part) done fairly soon. But of course, as I have already demonstrated, I am proficient at bonehead moves, so I must not go too fast and keep my pictures coming so that the masons on this site can help me to learn humility.

[Tapir Force]

Re: Tapir Force Steps up to the plate!

Dino Pizza,

The dome gives me about 2.5" for my insulation on the outside of my soldiers. But I intend on using concrete board on the outside of the enclosure and filling with loose vermiculite. That gives me an addition 3.5"on each side. I did something similar on my gasification boiler and although temperatures are not as high (never over 200℉) the insulating properties are amazing. I have looked at a lot of your posts. Your kind words mean a lot.

Robert

[Tapir Force]

Re: Tapir Force Steps up to the plate!

Here are my soldiers standing around waiting for me to repair my design flaw of taking the firebrick subfloor too far beyond the perimeter of the dome.

As I am working on this project, I am doing it with an audience of four parrots in outdoor flights and two scratch and dent rescue dogs. They seem highly amused as begin taking this apart to repair my floor.

[stoveup]

Re: Tapir Force Steps up to the plate!

Tapir,

That's a great start. I can't see it in the photos so I'll ask - is there insulation below the oven floor and the soldier course?

[Tapir Force]

Re: Tapir Force Steps up to the plate!

Stoveup,

There is a 3.5"reinforced concrete floor. On top of that is a 3.5 inch slab of vermiculite and Portland cement insulating layer. Then there is a layer of 12"x15"x2" firebrick floor on top of the insulating layer. Then the oven floor and soldiers. I am modifying the 12"x15"x2" firebrick floor as it turns out that it will probably wick off too much heat in its present configuration. Thanks for looking in!

[stoveup]

Re: Tapir Force Steps up to the plate!

Right - you have the insulation underneath covered and, if I understand your modification to the subfloor, it will allow you to insulate down to the vermicrete slab so your oven can be completely wrapped by an insulating layer. That's the ticket.

Keep on keepin' on!

[Dino_Pizza]

Re: Tapir Force Steps up to the plate!

Filling in with loose vermiculite is the way to go, wish I'd a done that. And it's good to here your going to "modify" your floor that extends beyond the soldiers. You might as well do the extra work now for a good working oven.

What's your final dome height going to be? Are you planing on a half-sphere at 21" or a squished elliptical a bit lower, like 19" ? With your soldier course already at that angle, your 1st row or 2 may need none to little tapering .

It's looking,
Cheers, Dino

[Tapir Force]

Re: Tapir Force Steps up to the plate!

Today, I cut back my firebrick floor. Ding, dong the wick is dead! I then proceded to mix up some more vermiculite concrete and poured the insulating mix around the floor where the firebrick had been. I believe I have solved the problem and I will start cutting my first and second tiers.

Dino,

I was thinking about a 21" dome. I have read much about both types and find that the arguments for both shapes are compelling. But since I can't make a choice based on the merits, I think the full arch looks a bit more ancient to me. I am all about old.

[Tapir Force]

Re: Tapir Force Steps up to the plate!

Today, I got caught back up on the opening to the oven. I had enough of my 15"x12"x2" firebricks, I decided to cut the layers to the entry that would include a reveal as so many have suggested. I cut 4 of the blocks per each side, but by the time I mortared and placed my arch, the opening exceeded the 60% of the inside height of the dome rule. I took a layer off and that brought the height to 6" before the beginning of the entry arch. The ratio went back to within the proper range so that I do not lose too much heat. I am going on a trip for a few days, but will try to mortar in the front tomorrow before I leave. Next week I should get to setting the tiers.

[Tapir Force]

Re: Tapir Force Steps up to the plate!

Just got back from a trip yesterday prepared to do some serious cutting on my first three course of brick that sit on my soldier course. Got through the first set of angles and laid it out on the soldiers. The cuts were surprisingly accurate and my geometry genes still seem to be in tact. I sat down to do check my figures on the next course and then headed to the saw to cut them, this time both bevel and angle, but I had to clean my saw up from yesterday. I had purchased a 10"brick saw from HB and it has been a dream. I clean the saw between every session to retrieve the fireclay and allow enough water in the trough. To my dismay, the little pump on the saw was dead. I had cleaned it three or four times already and it had not given me a scintilla of problems up to that point. I bought it on April 2nd and so was under warranty. I called the store and they told me to bring it back. I hate to return the whole saw for the little pump, but I have to keep going and can't wait for a part to be shipped. Man, I was on a derned roll and can't slow down. It is a sixty mile drive.

On a separate note. The mortar work starts in earnest tomorrow. I have read that My soldiers would be adequately held by just using a mixture of fireclay and water. I am not opposed to using motar to stick them in. My sense is that the lateral pressure from the weight of the dome will be significant on the 20 degree bevel of the soldier course. Any thoughts?

[Tapir Force]

Re: Tapir Force Steps up to the plate!

Drove into Denver. HF gave me a new pump. They are selling a good saw at a fair price and they are standing behind it. I cannot say enough about the 10"brick saw from them. Managed to get back and still cutanother arch for my entry and my big push tomorrow.

[GianniFocaccia]

Re: Tapir Force Steps up to the plate!

Nice job, Robert. My company's corp office is in the Denver Tech Center. If it ever works out, next time I'm there I'd love to look you up and check out your oven.

John

[Tapir Force]

Re: Tapir Force Steps up to the plate!

My wife and I would love to have the company and show off the oven no matter how it turns out.