36" in Seattle

[ThisOldGarageNJ]

Re: 36" in Seattle

Kebwi,,
looks fine,,, I screeded mine with a 2 x 4 and just tried to finish the exposed area's.. In the spring i will extend mine for a bigger cooking shelf, then polish it..
cheers
mark

[kebwi]

Re: 36" in Seattle

While I wait for my hearth to set, here's my little subproject. Yes, I'm the kind of person who actually CADs a stand for his tile saw, but in the interest of chronicling my adventure, here it is. I hope to have this puppy up and running by this weekend so I can (after laying down the InsBlock) get to work!

[ThisOldGarageNJ]

Re: 36" in Seattle

hey keb,
looks cool,, I do some stuff in corel, sometimes i like to draw it first to lay it out on paper,, then its easier for me to build as i feel ive already done it..
Nice drawing.. what program
Cheers
Mark

[kebwi]

Re: 36" in Seattle

Meshwork. It's old, but I don't want to pay for something newer.

[ThisOldGarageNJ]

Re: 36" in Seattle

hey.. it looks good.. I work with graphic artists that cant do that with new stuff... Sometimes its good to stick with what you know

Cheers
Mark

[kebwi]

Re: 36" in Seattle

Took the forms off the hearth. I think it looks great. I love the sharp edges and corners. The stack of blocks inside the hearth will be removed of course.

And...my heavily over-engineered tile-saw stand. Compare it to my 3D model from earlier in the thread (or a slightly updated model in my album).

Time to start cutting and laying InsBlock 19.

[Dino_Pizza]

Re: 36" in Seattle

Great looking stand. I always recommend getting the stand with the saw but yours has lots more character than the HF stand.

[kebwi]

Re: 36" in Seattle

Thanks. Considering that virtually all of the parts (with the exception of the casters and the bolts) were already purchased for concrete forms, it didn't cost too much to build, far less than the HF $60.

However, considering the time that went into it, I would not recommend to any future readers of this thread that they go this route for the purpose of saving money over the $60 HF stand. It still cost some additional materials. In the end I might have saved $40, but it cost me three evenings after work and a chunk of my weekend!

I would only recommend this if you simply want to do it for fun...and that is certainly reason enough, but don't do it because you thing the HF stand costs too much. That's all I'm saying.

Cheers!

[Neil2]

Re: 36" in Seattle

I hate to say this, but I don't like the look of your suspended slab. Too many voids - I think the concrete mix was way too dry (judging by the photos). Is it "crumbly" in any way ?

You may want to think about testing it somehow before continuing. Maybe give the edge a few soft wacks with a sledge hammer after it has cured a week or so.

At a minimum, you should parge all the voids on the sides and the bottom.

[fxpose]

Re: 36" in Seattle

Adding to Neil's comments above, I would like to see a center column or support under that slab, even though most of the oven weight will be concentrated near the perimeter of the slab. That was my initial reaction when I saw it. I would personally do that for the peace of mind.

[kebwi]

Re: 36" in Seattle

Ugh, okay. I looked up parging online and it sounds like you are referring to cake-frosting the concrete with a really fine (non-aggregate) concrete, or effectively mortar. So, should I make this mortar out of Portland, lime, and sand, just like the refractory mortar but without the fireclay, or is there some other substance I should use for this task.

At least my rebar is 1/2" on an 8" spacing, so it's much denser steel than most of FB ovens from what I've seen, for better or worse.

As I said before in this thread, I am very confused about how concrete is supposed to work. I concede that my foundation was probably too dry, so I mixed wetter for the core fills and wetter still for the hearth. I mixed it for the hearth such that a glove-full grabbed from the mixer was downright runny because I was so disappointed after the foundation...yet the hearth turned out dry. I am really perplexed, I just don't get it.

At any rate, even before you mentioned parging, I had envisaged something like it on my own. I imagined using a really smooth cement to fill in the rough concrete. I didn't realize until you mentioned it that anyone actually does that. Thanks for the tip.

So, what precisely should I use for parging?

Thanks for the suggestion of a central column too. That's disappointing, it will make the interior space far less useful, but if it has to be done, so be it. I hope I can wedge concrete blocks up in there now. I guess I can angle grind the last block in small increments until it squeezes in. It'll be dry stacked of course...unless you think I should fill the first three blocks with concrete, then make a solid block for the last block, and fit that in place, such that the column is solid concrete.

[kebwi]

Re: 36" in Seattle

Actually, after some research on parging, it looks like the suggested blend does not include lime: just Portland, sand and water, in some combination which I am unconfidently unclear about.

[Neil2]

Re: 36" in Seattle

Go for a 5:1 mortar sand to Portland mix. Or you can buy premix mortar. Before parging make sure your slab is thoroughly wetted.

[kebwi]

Re: 36" in Seattle

Wow, okay. A few parging references on-line suggest almost 1:1 sand and Portland. Of course 5:1 seems much more typical of other mortars so I find your figure considerably more believable in that respect.

Wet isn't a problem. It's Seattle and it's fall. That means rain every day and fairly humid considering the colder temps.

Thanks for the tip. You said I should parge the entire underside as well as the sides...but not necessarily the top? Doing the sides makes sense to me since they are the most at risk of degradation.

[Dino_Pizza]

Re: 36" in Seattle

If others think the center expanse seems too wide and you want to add support, what about getting a 36" or so square steel plate, 3/8" or 1/4" thick for under the slab? You can hold it up like Neil says with a single center column or just add a column of cmu's at the rear and front or from corner to corner (diagonally opposite each other) to hold up the steel plate at the edge. I think you just want to take some of the weight away from the middle slab and it should not take much to do that.
I think your steel work in the slab was exceptional so it's got to be strong but, ya...that cement is not as "strong looking" as I've normally seen. I don't know much about concrete so this is just another idea.