Michael's 42" in Portland

[mklingles]

Hello and thank you for everything I've already learned at the site.

I'm starting a 42" oven. I got the foundation in on Friday (yea cement pump!). Blocks for base will go in next weekend and the hearth slab will be in a week from Monday.

The cement pump cost me an extra $300. The mini-mix cement delivery was only a little more expensive then buying 80 lb sacks of concrete mix. But, since I had to go up 8 stairs from the curb and wind around behind the house. It was money well spent. The foundation couldn't have gone in any easier.

Still haven't decided if I will buy a saw or try to make few enough cuts that I'm okay with my circular saw and cutting dry. Anyone have any input on scoring and breaking fire brick? Seems like the majority of my cuts will be just cutting bricks in half for the dome.

One more question: I just bought the parts to build an "indispensable tool". Am I better off using that or using forms? Seems I haven't seen many pictures of domes going up with forms, but lots of indispensable tool photos.

Thanks.

[100million]

Re: Michael's 42" in Portland

buy used
portland all for sale / wanted classifieds "tile saw" - craigslist

then sell used IT IS THE BEST WAY
I would get a saw

[DrakeRemoray]

Re: Michael's 42" in Portland

I second that, you are better off with a wet saw.

I built mine with forms several years ago now. More people are using the indsp tool now. It certainly gives you better control of the mortar joints to use the tool...

See my thread for a form based build. If I did it again I would probably use the tool.

Drake

[mklingles]

Re: Michael's 42" in Portland

I've been considering trying to create a thermal barrier between the oven dome opening arch, and the chimney vent entry arch.

My question is does this have value? How hot do the bricks in the entry archway get and how hot do the the floor bricks in the entry way get?

My idea for implementation is to use a bit of the 2" FB board between the oven arch and the entry way arch. Then mortar it over with perlite and cement so it's not directly in the flame. Also I would transition from medium duty fire brick in the floor inside the dome to light weight insulating fire brick in the floor of the entry way. Good idea? Bad idea?

Oh and how come I haven't read that cinder blocks are heavy. I borrowed a pick up and still had to make to trips. Some Pictures will go up tomorrow.

[vintagemx0]

Re: Michael's 42" in Portland

Hello Michael,

Congrats on starting your oven! We're in the Portland area too (Rock Creek area off SW 185th) and we built an oven last summer. We love it. We are really looking forward to honing some cooking skills this summer.

It's been our experience that the landing area and inner areas of the entry arch do get hot, but nothing of concern. I don't know if insulating the area from the dome would help very much, as it is the radiant energy from the luminous fire that seems to heat these areas up. I've felt-around on the bricks outside of our oven and they are pretty cool, so I'm pretty sure there isn't much conduction issue there.

We were planning on tiling the landing area on our oven, but we have since decided not too because of the radiant heat. We feel that if someone put their bare forearm down on, what is now concrete, that it would be "oh crap!" hot, but if it were slick, smooth tile actual injury could occur. Again, the source of heat is radiant from an active fire and not conduction through the bricks.

Imagine how heavy those blocks would be without the holes in them!

If you want, you are most welcome to come by and throw back a beer over some oven-gab.

Best wishes,

The Morgans

[fxpose]

Re: Michael's 42" in Portland

Using insulating firebricks for the landing surface is a bad idea. They're too brittle and gouge too easily, even with your fingernails. I used them as my thermal break between the two areas but I don't know how effective that will be as my oven build is not yet completely finished. I will soon find out...

George

[mklingles]

Re: Michael's 42" in Portland

Here's some photos of my stand. Nothing out of the ordinary. I dry stacked the blocks. Things were level enough for me, so I didn't mortar the bottom of the blocks to the slab. I'll have the concrete pump back on Monday, so I will most likely just have all the cores filled.

[Neil2]

Re: Michael's 42" in Portland

Avoid using the term "cement" when you mean "concrete" (unless you are a Beverly hillbilly).

Using the incorrect terms can lead to confusion. One fellow on this site mixed his pearlcrete using premix concrete instead of portland cement. He had to do it over.

[mklingles]

Re: Michael's 42" in Portland

I sit corrected, and I corrected the post above replacing concrete with cement.

[vintagemx0]

Re: Michael's 42" in Portland

Have you gotten your bricks yet Michael? We got ours from Mutual Materials. We built a 36" oven and purchased 200 bricks. We ended-up with about 7 extras when we finished. (Lucky guesstimate)

You have the "grunt" work behind you for the most part. We look forward to watching your build.

Kind regards,
The Morgans

[mklingles]

Re: Michael's 42" in Portland

I'll get my bricks from Mutual Materials too. Curiously they make the concrete blocks that Home Depot sells in town, but Home Depot retails them for half the price Mutual Materials charges. Very strange.

[100million]

Re: Michael's 42" in Portland

I paid 1.13 a brick at Mutual Materials in Bend oregon

[mklingles]

Re: Michael's 42" in Portland

I got my bricks, I picked up a saw, the hearth pour went well and today I took the side forms off and started on the floor.

I uploaded more pictures to my album. I did my plans on a drafting board (I get to work on a computer all day long), so I took some pictures didn't come out great, but they work:







Here's the insulation board cut and ready. It doesn't seem like finish work, but getting the front edge square and placed correctly will matter. I'm having a hearth stone cut to fit around my arch, so it all has to be in the right spot.

[mklingles]

Re: Michael's 42" in Portland

On friday I did a bunch of geometry. My oven will be 42" wide and 18" tall. I plan for arch of the dome to be hemispherical. Given the height of the dome is lower then the radius of the floor, the indispensable tool will not be at the center of the sphere. I think I've got it all worked out. Distance from the base of the tool to the face of each course of bricks. Once I got started I also worked out the length of the 4 edges of the trapezoid for each course of bricks. I'm going to wait to test my math on the build before I post it.

I plan to cut my bricks into trapezoids with a single cut. The piece cut off will be rotated and mortared onto the opposite side of the brick. I will only angle the side edges. I'll leave the brick at 2 1/2" front to back. Since the dome is hemispherical the angle between every course (moving from bottom to top) is the same, and that creates a gap at the back of about 1/2".

[mklingles]

Re: Michael's 42" in Portland

I got my floor in. It's set in sand. You can see the 4 thermocouple connectors in the front corner of the picture. I put 4 in the floor: 1 about 1" from the surface (crappy drill bit didn't want to go any further), 1 about 2" from the surface, 1 at the interface between the brick and the insulation, and 1 at the interface between the insulation and the concrete. These are the "standard" ones from Omega - they are only rated to 900 deg F working temp. They might hold up and they might not. I've got some special order ones from Omega coming to go in the dome. They are rated to 1600 deg F.