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  #31  
Old 09-01-2013, 12:21 PM
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Join Date: Jan 2013
Location: Tochigi Prefecture, Japan
Posts: 620
Default Re: Filling joints in hearth slab?

Hello Richc:

Well it looks like your castings are a bit off. If they are not off by orientation, like you have a vertical joint where it should actually be a base joint... then you are going to do some serious scribing to make them fit.

To do this, you need to get your hands on something that will cut the refractory cleanly so that you can make the necessary adjustments. A small angle grinder with a diamond blade, for cutting and maybe a cup type diamond leveling cutter. Actually the same cutter that you would use for cutting brick for a hand held grinder.

How I would tackle this would to first decide which are the most critical seams. To me, I would want the center of the top of he dome to be in perfect alignment. I think that you need to use some type of hydraulic jack and some wooden blocks to protect your casting. The top wooden block should be able to touch all three pieces of your dome.

You must raise the center enough so that it becomes all the same height. In doing this, your vertical seams should come into alignment. Once that you have accomplished this, You will need to scribe the bottom of the dome sections so that you will eliminate any dome to hearth spaces.

My term scribing is just marking with something that is the thickness of the largest gap and cut that excess off all offending pieces. You should be able to do this so that --I don't know the currency of Ireland??? Maybe it is the British Pound??? Anyway, you should be able to make it tight enough that one of your paper currencies cannot easily slide between the joints.

This is something that you can do--and something that must be done to get these castings into alignment. If you don't, you are just asking for problems down the road.

You want to look inside your oven and see a nice smooth surface. Too bad the company that supplied the castings has such a poor quality control department!

Another little bit of advice--try not to set schedules when things must be completed by. With these oven builds, something always comes up --adding schedules to a hobby just makes for a lot of useless stress! Worrying never accomplishes anything except "the actual act of worrying"! Enjoy your hobby!

Another "old guy" bit of advice- if you don't love going to work at your regular job, change jobs --so that you do! You have to work all your life anyway so why not enjoy what you do!

I'm really lucky...I consider my job as my hobby, not that I have a lot of money and can be independent but because I enjoy looking forward to every moment I spend doing the little projects that I do--AND--someone else is willing to pay me for what I do! Best of both worlds!! Even though the pay is small, the rewards are great!

To get back on subject--Use the refractory mortar sparingly! Do not allow it to get onto your hearth surface or any area that would make a bond between the dome and hearth. It just fills the fine cracks, It can be plastered over the outside of the dome at the joints and feathered out. The joints will crack again there anyway but it helps to keep the cracks very small!

What is the deal with the landing? Do you have another cast section that forms the landing and chimney transition? Do you have any sales literature that shows a completed oven by this company?
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  #32  
Old 09-02-2013, 04:01 AM
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Join Date: Jan 2013
Location: Tochigi Prefecture, Japan
Posts: 620
Default Re: Filling joints in hearth slab?

Don't get worried that this is some kind of big job!

It really is not! Actually, if you spend a couple of hours working at it, it will be finished and you can be on your merry way doing the next part of your oven build.

The idea of elevating the center is to force things into their design alignment. A quarter of an inch out of whack on the bottom telegraphs to huge amounts in other areas.

A good piece of advice--don't try to take too much off at one time! You can make some hardwood shims to place under the oven where it hits the floor. I would cut them from maybe zero to maybe 10mm taper. I do not think that anywhere on your base you will be more than 10 mm out of alignment.

You just have to dive into it and you will be surprised with how quickly things turn around for you.

I made matching forms for my oven- a three piece castable, and I thought they were perfect. Before actually pouring the sections, I butt up the adjoining forms and made minor adjustments--which I thought would put them into perfect alignment. Once the sections were cast and the forms removed--again I matched up the pieces. There was still some misalignment but nothing a diamond sanding wheel could not correct with a few minutes of grinding.

I am waiting to see your photos with the adjusted dome! Don't plaster it up with gunk before taking the pictures, I'd like to see how fussy you want to be with your own oven!
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  #33  
Old 09-02-2013, 05:28 AM
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Join Date: May 2013
Location: Ireland
Posts: 168
Default Re: Filling joints in hearth slab?

Just picked up diamond blade. Hope to get it done this afternoon if the kids let me!
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  #34  
Old 09-02-2013, 11:42 AM
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Join Date: May 2013
Location: Ireland
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Default Re: Filling joints in hearth slab?

So, I took some off the bottoms of the high pieces, they now fit quite well at the top but on the 4 vertical joints there's still large gaps at the bottom. Some around 30mm at the widest point.



This ones taken from inside
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  #35  
Old 09-02-2013, 11:48 AM
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Default Re: Filling joints in hearth slab?

Gaps on vertical seams



The guy in the refractories said not to worry, just fill them up with mortar. I'm wondering would it be best to order some firebricks, cut slips and mortar them into the gaps or should I just go ahead and fill them?
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  #36  
Old 09-02-2013, 11:55 AM
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Default Re: Filling joints in hearth slab?

I would not align the floor seams with the dome seams. If it were my oven I woudl offset them so the floor seams were at the middle of the dome pieces. Same as you would with brickwork

It looks in the pictures like you should be able to push the dome sections in at the base to get them to fit together better, but maybe it just looks like that...

What brand is this oven, if I might ask?
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  #37  
Old 09-02-2013, 01:03 PM
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Default Re: Filling joints in hearth slab?

Hi Deejayoh, I aligned the hearth in that orientation as it gave me the best fit for the entrance hearth base piece. The upper dome pieces can only sit in one orientation adue to the opening. Does it really matter, the fact that I've aligned the base and dome joints? I'm reluctant to redo it because it took quite a bit of work to get the base pieces to sit correctly, and I like the ways it ssitting now.
The pieces are cast symetrically so there is no 'bottom' side, this is the best I can get them sitting for now!

Last edited by RichC; 09-02-2013 at 01:07 PM. Reason: additional info added
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  #38  
Old 09-02-2013, 01:32 PM
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Default Re: Filling joints in hearth slab?

The upper dome pieces arent sitting very well on the base pieces. I'd really like to fill these gaps. I see Miku recommended using baking paper between the base and hearth to avoid creating a joint with reractory mortar and then burning it away afterwards.
Would this work: If I cover the base with baking paper, then fill the joints where the upper sections sit on the hearth with refratory mortar. When the baking paper burns away would I have an open seam or would the mortar penetrate the baking paper and join the upper sections to the hearth? Can this work? Seems like the only way to fill these gaps?

Deejayoh, now that youve pointed it out I cant live with those base/dome seam alignments!!! Pullign it down tomorrow to correct alignment......

My hurry at the moment is because my job is brigning me away 2 weeks from now, for 6 weeks. It'll be difficult to make progress when I get back because the weather will be pretty lousy here from november onwards. Id really like to get the dome and dome insulation done before I go, then I'd just have to work on the counter and final render when I get back.
Thanks

Richard
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  #39  
Old 09-02-2013, 01:38 PM
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Default Re: Filling joints in hearth slab?

Guys, what sort of sanding disc hould I buy for levelling the seams in the hearth slab? Is it just called a diamon sanding disc for masonary? What grit?

Thanks

Richard
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  #40  
Old 09-02-2013, 03:45 PM
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Default Re: Filling joints in hearth slab?

If you want to remove masonry or refractory material, get a diamond cup disk. Like this one:

RIDGID 4 in. Double Row Diamond Cup Wheel-HD-AWD40 at The Home Depot
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