Fnbrokens Corner WFO in Canberra, Australia

[fnbroken]

make a full scale template.

Without a doubt! Absolutely critical and will do one for sure.

In reading many of the build threads, it is most often those that skip this step that end up with issues further down the track.

I was planning on a few templates (cardboard is one thing we can get free around here) - floor plan (marking out the dome walls and floor, inner arch, TB, outer vent), dome profile, inner arch, outer arch and a 'brick'.

I would trim these to fit, then mark out on formply etc when finalised.

[Gulf]

......................I do enjoy using the graph paper, pencil and drafting set however - something therapeutic about it.....................................

I can relate to that Fnbroken. I do see the benefits of the new age tools. I used cad viewer extensively where I was employed. I even downloaded a free version to play with for the oven but, I let it lapse. Being old school, I keep going back to my old drafting board. One thing I learned years ago, is that any project 8' or under is easy to do in full scale for the final approval. I've drawn out a many of a project on the back of a piece of 4'X8' paneling.

I got the idea for this trick from my old employer. To upgrade in position (and pay) we were required to draw and explain the equipment and process for a pulpmill, one area at a time, from memory. They had dry erase boards placed around the administrative offices. It was required that you do this in a set amount of time. Being a slow country boy, I figured that I would need to have extra practice. So, I went to to one of the big box buiding supplys and bought a couple of sheets of the cheap white bathroom/utility room panel board that they had. It was about 10 bucks a 4'X8' sheet then. I think that it is a little over $12 a sheet now. Practicing at home on my off time, I aced every one of those drills.

A few years later, I had given those boards to a young coworker who was upgrading. I still had a few dry erase markers. So, working on the back of a chest type freezer, I was able to consult and verify (full scale) what a newbie builder was seeing in cad . I just had to make sure that I had cleaned the freezer before SWMBO got home .

My point to all of this, is that your case, (especially a corner build) to make a full scale template. It can be done on scrap card board box or poster board spliced together. You can set that template on top of your stand and see in full scale, if you need to make adjustments.

[fnbroken]

As an aside, soldier and sailor courses...

I really like the neatness of the hemispherical design...something about it appeals...

I'm going to going to be putting the walls onto the insulation - not the oven floor and leaving a 1/8" gap between them as recommended (stuffed with cardboard/taped over).

Using a 75mm (3") firebrick floor + some 7mm (1/4") form ply over the top to mount the IT etc that works out to be an 82mm (3.5") floor height. So I would need to match this in a 82mm high sailor course - before I start the hemispherical dome walls. It would also eliminate any gap at that point. Is this the right /recommended process? Having this first course level with the floor will mean no IT adjustments throughout the process?

Also, with an opening at 63% of the dome height at 345mm - should I make the vent opening 690mm to keep this consistent? Thats going to be a big change to the CAD plans! The alternative is I need to do couple flat courses to 95mm, then start the hemisphere on top...hmmm

[fnbroken]

Hey JR, playing with your plans - sweeet... although I think I get a handle on it - then it doesn't play nice lol...patience

So, edits i'm trying to make:

1. Reduce the inner arch protrusion from the dome to 50mm (2") - currently it's 66mm (2.5")
2. Change to a 75mm (3" reveal) rather than the current 50mm (2" reveal). This givs me a total outer vent ID of 650mm
3. The outer vent bricks will overlap the inner arch bricks by 25mm (1") - stuffed with rope/sealant.

Assuming a TB of 10mm (3/8"), points 1 and 2 will significantly reduce the amount of beveling/notching into the outer vent brickwork for the overlap, more brick (stronger) and wider (more room to work the oven). Doing this because I think I can now see from the plans I have the space to do it.

Between points 1 and 3, this will gain me an inch or more wriggle room at the front of the oven.

I see what you mean by having more 'landing' to work on now. Will definitely factor in some formwork to pour an arc'd extended landing of 150-250mm. I wont include this in the hearth as this section is non weight bearing and will affect the head room I have to get in and get wood from underneath it. I can see my 4 year old (6-7 by the time I'm probably done) getting this task ....



Fine tuning and working out those distances if you have time would be super handy as a starting point for a cardboard mock up.

[JRPizza]

I started out keeping track of my costs, but got tired of tracking every nickle and dime (more like $10's and $20's) since I was always running to the supply store for a few more bricks or a new blade (or something else I didn't have). I also think my original estimate was off somewhere between 2X and 10X. Hopefully the numbers won't be so high as to scare you off - the oven and outside area you are planning is a lifestyle choice and as long as you don't move (or divorce) it will be worth everything you put into it in terms of enjoyment.

[fnbroken]

Thanks JR, and for the plans - will need to find a few spare hours to have a crack at FreeCAD. Having a template to start with certainly make things easier!

Perhaps creating a dropbox account, making it public and putting the complete plans for your 39" there may be the way to go. Others can add their CAD plans to it over time to have a 'gallery' of pre-done plans for members to leverage.

That said, half the fun is actually working thru and understanding the intricacies of the finer details. Learning a new skill like this is always useful (I do enjoy using the graph paper, pencil and drafting set however - something therapeutic about it)

Russell, believe it or not - materials are cheap compared to the labor for someone to do it! And being in Canberra, we tend to pay a premium of 20-30% on top of pretty well anywhere else in Australia. I'm going into the details of my build, calculating as much as I can, as I plan to do a run to either Sydney (3 hours drive) or Melbourne (8 hours drive) on a supplies run. The cost of one trip like this will save me more than that in the saving on the price of materials. Hopefully I can tie it into a weekend getaway with the family to justify the trip to the fun sheriff. I would do a back-load on a truck, however they usually require you to unload when it gets to the destination. Unloading over a tonne of firebrick etc by hand in a hurry doesn't appeal to me and will probably lead to more damaged bricks than it's worth.

Today's task is going through and developing a financial model for the materials I will require now the design is 'roughly' there. Quite a few builds have found the 39" or 1000mm WFO is an optimal size when it comes to procuring materials. Want to also look at the impact of using 50mm and 75mm firebrick in the construction. I have done this for the foundation, stand and concrete hearth and it already tops $1,000. Scary.

[JRPizza]

The first CAD of the arch intersecting the dome at the top is definitely something I missed when placing the arch. Was it the CAD program that recommended the 620mm distance?

I think lots of people miss it, or at least did in the past, which is why there were earlier builds that had to compensate for the arch and dome not wanting to intersect properly. If you go back and read the thread I linked to below, you can see I was only thinking of the lower intersection until Gulf helped me understand that the arch intersects the dome continuously but variably from bottom to top. Yes, I got the 620 from my cad sketch. When you make your cardboard layout, and have your arch form built (both things you should do before you get too far along) you can place the front of the form 620 from your oven center and use your IT or a tape measure to see how a top dead center arch brick will be "within" the dimensions of your inner and outer dome diameters. That is when you will know for sure you have it right. I can also help you find where the center of the oven should be on your hearth, but you will want to put your oven template on the location to double check. I always liked using models at work, but never trusted them enough to not do a spot check

[UtahBeehiver]

Either/Or. I used 3" thick brick that was even odder size 5.875" wide x 9" so any brick size can work up to a reasonable point.. I would go with the best price for the quality. You being in Aussie land, brick and material cost are a crazy insane cost factor.

[fnbroken]

So something that has been 'bugging' me for a little while now - here in Oz, the standard firebrick is 230x115x75 or 9"x4.5"x3.0" - this size gives me 9 courses using Deejayoh calculator on a 42" dome.

Most builds on the forum however use a 2.5" high brick - or 63mm - resulting in a several more courses - and a much neater finish (albeit a lot more cuts!).

Another standard in Aust is a 2.0" brick, or 50mm - making 15 courses! Would I be better of going with this size brick?

[fnbroken]

Thanks heaps JR - looking good, appreciate the guidance.

I will need to pour the landing and surround at some point (to cover the vermicrete etc etc) - so when i'm it forming up making it extend further in front shouldn't be a problem. I will add extra rebar to the front and cover it to ensure I have sufficient strength there - or I recall someone using what looked like large bolts sunk into the initial hearth to secure it by. Given it wont have a great deal of weight on it, should be ok - plus keep as much headroom on the stand (I'm 6'5" tall).

Importantly, all the main components fit on this size hearth. That said, going an extra half a besser block in each direction (200mm, 8") would give me a lot more room to move? Will have to measure up how much space I have in the backyard to accommodate it.

Also, by the time I get to this point, I will have a better idea of how much room I would like in front of the outer vent (I have no idea - never seen one of these in real life!)

The first CAD of the arch intersecting the dome at the top is definitely something I missed when placing the arch. Was it the CAD program that recommended the 620mm distance? I was kinda working backwards - with the brick to extend out 50mm at the base....that it would just 'work out' when I got to the top by moving the bricks in or out as required. It actually needs to intersect the inner dome/inner arch at 345mm off the floor! Which logically is further into the WFO - roughly 100mm in fact. Interesting...

[JRPizza]

OK, I'm running out of free time today - here is a plan view I made using the above inner arch distance and your measurements. I didn't bother laying out the heat break, but that is only a half inch and really is in the noise. You could move the inner arch back if you wanted - I showed a protrusion of about ~64 mm for the inner arch at the bottom of the dome, so you could move it back up to about 50mm and still have room for your heat break overlap, but that is cutting it close. What the picture also shows is you might want to extend the front of your slab a little like I did if you are planning on putting on any decorative facing, or just want a little more room. I think I have the dome about 45mm from the edges in the rear, so the front is going to be tight. I also uploaded an axometric view just for grins. I would be more than happy to give you a copy of the file if you want to play around with FreeCad - it's nice to be able to move things around on your own and the price is right!

[JRPizza]

Inner arch placement is indeed where the arch meets the dome, but to avoid going out of round you just need to make sure you are intersecting at the top of your arch. Folks that put the arch too far fore or aft have to deviate from round to meet the arch.
If you look at my post #28 of this thread "https://community.fornobravo.com/forum/pizza-oven-design-and-installation/getting-started/355718-hearth-size/page2" I showed how I can move my TDC brick fore and aft and still meet the dome, so there isn't just a single right dimension (I don't think). I used your door height and it looks like I would put the forward face of your inner arch at 620mm from oven centerline which would maximize your cooking floor, deep the dome round, and give you a nice arch protrusion. I'll work on a plan view with that distance and your other dimensions to see how that looks. You are going to want to make a full size (cardboard) layout eventually but these dimensions might help.

[JRPizza]

Greg, you don't have any rear walls yet, do you? I decided it would be easier to build walls after the oven vs walls first, so I didn't have to deal with obstructions and ended up about 50-60 mm from the edge of my hearth. I still might put some tile on, but there is room for that. When the walls finally go up I'm not going to be going back behind my oven unless I get the itch to clean out the spiders etc that are going to collect there. Like you I wanted to push the dome as far back as possible to have room for a landing without needing to add an extension, and to have the areas immediately to the sides for pans, utensils, and beverages. I did overhang my block stand a little in the front to make the width at the narrow point close to the width of the outside of my arches.

[fnbroken]

So a search of weep holes - comes up when a vapor barrier is being proposed between the hearth and insulation to allow any errant water a way to escape. A post by David S also recommends including a slight slope away from the center of the dome to the weep hole(s) to assist in this process. Will add this to my notes for this stage. Thanks for the tip!

Any further ideas or tips? Easier to incorporate them now!

[fnbroken]

Thanks JR / David - the scale drawing has a gap of about 50mm (2") - happy to go to 100mm if there is a good reason for it - I essentially pushed it as far back into the 10/2 position as I could to allow maximum landing depth. From a usage perspective - this will be no-mans-land going forward so didn't want leave it empty. Why do I need 100mm - the only thing i can think I need to be able to rest here will be the edge of a jig that I will use to ensure the dome stays round....

The inner arch placement occurs where the WFO side of the inner arch intersects the inside diameter of the dome - where the distance is 500mm (19.5") - make sense? Is that how it is positioned? If you look at the drawing, it is the distance labeled as '500'.