Bacterium's 2nd build

[Bacterium]

Re: Bacterium's 2nd build

Colin,
Plan so far was to overlap the 2 arches by about half a brick but have the outer arch with an airgap above inner.....not sure about floor but probably an air gap somehow.

[Bacterium]

Re: Bacterium's 2nd build

Manage to get up to the third layer tonight....Basically I am cutting the brick sides. I sorta guessed it shaving about 5-10%degrees per side for 3 bricks, made some adjustments with my saw guide then cut the rest for that layer. Second course I was a bit off but by the third I got my "eye in" and matching nicely..... gee this is addictive

Arch starts to get out of synch with the layers. I'm thinking of doing layers 3-6 all the way around except 2 bricks wide from the arch. Then cut/fill in up against the arch.

...mmm was going to comment on another thread but thought it might hijack. So the big question is Cut side face points inwards (exposed inside dome) or outwards (covered by dome insulation etc.).

Well I'm using second hand fire bricks which were recovered from a house chimney which was pre 1980's (most likely pre 1970's). Outer edge of the recovered bricks are a bit rough as you would expect for age so the outer face is not soft just rough. This obviously won't give a nice tight fit for the dome inside.

They are a proper fire brick (not just a plain pressed red) as I managed to track down details through some of their markings.
Now I used to be of the opinion that you always put the cut side out believing the outer (fired side) would be harder. Well I was having a look at them (see pics of cuts) with an old brickie mate and he said effectively as long as a brick is baked all the way through the integrity should be the same.

So going over the cuts the cut side is quite tough, occasionally you can spot a flaw (more so a crack) so I don't use that but I'm starting to think in the situation where you are using seconds for fire bricks, why not point the cut face into the fire side of your dome?...........

The other part of my reasoning is as these bricks have a dirty (outer side) that you can see was exposed to the fire inside the chimney, where they originally where.... is that something you want exposed inside your dome (food cooking) . Possibly not if it was a domestic oven, definitely not if it came from a commercial use.

This has been discussed in part before but thought I'd post up my experiences/thoughts to add to the discussion.

[ATK406]

Re: Bacterium's 2nd build

Hello Damon,
I like your logic on reclaimed firebrick. These ovens don't generally put the refractory properties of the brick to test (they'll probably never see temperatures in excess of 1200F).

On the subject of your dome/arch transition; In my opinion, this is the most challenging part of the build. The dome build itself is pretty straight forward once you get the hang of it (as you've already seen). The intersection with the arch takes some planning. I would be careful about putting this off too long or you might paint yourself into a corner (or brick youself into a teardropped dome as the case may be). A teardrop dome is not a big deal but the lack of symmetry makes closing out the top of the dome a bit more difficult. Just my .02.

Good Luck,
Regards,
AT

[Bacterium]

Re: Bacterium's 2nd build

The teardrop can be a concern.....albeit a "hidden" one. I've been cutting a whole layer of bricks and then I mortar, rather that cut/mortar each couple. My strategy works until you get to that point where you get a join meeting up with one on the below layer. So I'm making it occur up.towards the arch....see how it goes next layer.

My arch bricks towards the top(the back) would be about 40mm inside the adjoining rings. Hopefully to stop the teardrop effect and allowing me to trim both arch and layers where thy meet. I'm hoping this will allow me to cut arch top and rings together. I didn't quite have the confidence where Doug built his arch first.

[Bacterium]

Re: Bacterium's 2nd build

I had a play with the dome spreadsheet calculator. I guess part of my issue is time available to perfect my cuts between all the family/work/life stuff. Tonight is blowing and raining so just topping up my glass will brick saw sits asleep!

Basically I measure the front width and rear width of brick eg.,to find my angle I cut line 12mm in from each side of the front and then 2mm in from each side for the back. Then basically I set up my saw guide to achieve this angle for every cut. For every layer I increase the angle in my saw guide.....seems to be working ok, however I did notice on layer four, a small gap appeared at the bottom of where each bricks join side to side....is this what is meant by "inverted V"?
Wonder if it will widen or if it will stay the same, it's only just noticeable at this stage.

[Bacterium]

Re: Bacterium's 2nd build

Bugger, thought I had an easy solution. My first oven was simple half brick bolster cuts.....or splits.

Saw you mention to trim one side before, It's now doing my head in. So does that mean once you cut a brick in half you then only cut one side.....on an angle front to back and at same time angled top to bottom?.......
Your patience is appreciated.

[Bacterium]

Re: Bacterium's 2nd build

Ok, thanks

Looks like some experimenting on the saw tomorrow night will help me understand your point....... Not going to try and match Colin's saw jig just yet!

[Bacterium]

Re: Bacterium's 2nd build

Doug I got it

First, I worked out how to do the single side cut (as opposed to doing this angle cut on both sides of the brick which is effectively half the amount)
But
I didn't angle it to get rid of the inverted "V" because I just cut it flat on my saw bench
So
Then I worked it out.......the single side cut needs to be worked out on 2 different planes.

Effectively one cut but you need the brick to be setup to be sitting at 2 different angles as you drop the saw on the cut........

[Bacterium]

Re: Bacterium's 2nd build

And don't worry I'm not doing the top/bottom taper cut......maybe next oven but I think I need my brain to develop in another dimension for that one.....!!!!!

[oasiscdm]

Re: Bacterium's 2nd build

Hi Damon/Doug

ut......maybe next oven but I think I need my brain to develop in aAnd don't worry I'm not doing the top/bottom taper cnother dimension for that one.....!!!!!

or use tapered bricks as that takes out the third diemsion See picture using combintion of 75/51/65 bricks. although i guess you have already pruchased bricks.

Doug I got it



Effectively one cut but you need the brick to be setup to be sitting at 2 different angles as you drop the saw on the cut........

Thats why i copied Russell [Utahbeehiver and others] Jig. It allows the bricks saw to do compound/mitre cuts.




I have been wrestling with this too. I am using tapered bricks and have worked out the formulae to create a 1 metere arch, as i am looing at no more than 5 mm at most mortar joints less if possible. I would prefer around 2mm joints but maybe thats too hard.

From where i sit there are three distinct things happening with the bricks, tilt/side angle/taper [top and bottom].

If you check the thread Dome Spreadsheet Calculator on tools tips and ticks thread, Deejayoh answered a question i had with a diagram of the bricks explaining tilt and side angle cuts for me. This helped a lot.

With Doug's cutting one side [thanks doug i think i get this now] explanation and Deejayoh's picture it will make sense.

Thanks for the complipment re Jig. Not far from seeing how it operates on the dome cuts, i like that it is infinately adjustable [get exact angle needed] and i can not lose the set angle on both sides.

[Bacterium]

Re: Bacterium's 2nd build

Colin I can see how tapered bricks would be a good starting point.

The whole multi angle cutting thing is a bit like the red pill or the blue pill in the matrix.
Last night I took the red pill.

[oasiscdm]

Re: Bacterium's 2nd build

Stuff the pills. A nice henschki shiraz was my choice.

[Bacterium]

Re: Bacterium's 2nd build

Ok, a good shiraz is better.

I'm about a third into laying level #6.......gravity will be a challenge on the next level just getting away with it for now.. Thinking if I should see if the wifes fit ball (dusty one in the corner) could be an option as a form from here on up. Can always deflate it a few hours later to clean up the inside.
A mate of mine tried this in his oven, anyone else tried it and see any drawbacks?

[Sharkey]

Re: Bacterium's 2nd build

I cut a plywood disc that was just a bit bigger than the remaining opening and inserted it up into the top of the oven on a pile of bricks and then built a mould out of sand. Once the bricks were cut and placed I mixed up a wet mix and just poured it over. The sand sops up the excess so it was easy to clean up the inside later.

You can get the exact shape you need.





It turned out to be the easiest rows of the whole build and I wished I had done 5 or 6 rows like this.

[Bacterium]

Re: Bacterium's 2nd build

I used the sand cap on my first build and it was great for.tweaking the shape and building those last rows all in the one day. I'm wondering if I stay with my current method and cut/lay a layer every 2evenings:......or just bite the bullet and take a day off and make a last lunge...!