FINALLY!!! - Start Of Building My Oven

[david s]

Re: FINALLY!!! - Start Of Building My Oven

volume of a sphere is 4/3 x 3.142 x RxR
Calculate the volume of the outer sphere (24 +3") and subtract the volume of the inner sphere (24) then divide by two because it's a hemisphere. There will be about 15% reduction in volume when you add water to the dry castable. You will also need some more castable to make the flue gallery/ manifold. You don't want mass here so make it thin.

[david s]

Re: FINALLY!!! - Start Of Building My Oven

Your trolley calculations are correct, but you might be better to make it bigger, so you wont be so close to the edges.

[david s]

Re: FINALLY!!! - Start Of Building My Oven

After the fire has done its job of heating you will need to remove some coals to give you space to cook. Yes your oven will cook a 12" pizza.
You will want the outside shell really strong so I suggest you use chicken wire (the small stuff cut into short overlapping strips) over your blanketbefore you stucco. You can place these chicken wire strips in place as you go, starting from the bottom and working up the dome.

[Oven_Man]

Re: FINALLY!!! - Start Of Building My Oven

Hi David

Thanks for the calculation on how to work out the volume. I was pretty bad in maths at school but I'll try and work through the calculations and see what I can put together.

You will also need some more castable to make the flue gallery/ manifold. You don't want mass here so make it thin.

I guess this refers to the vent. I was wondering whether I can fabricate the vent out of metal as this will work out much lighter than refractory cement but my concern is heat loss from a metal vent.
Will such a thing occur and is a metal vent advisable

I will make the trolley slightly larger but don't want to go to large or else it may not fit into a Pickup Truck or Trailer.
By the way, what is the size of your trolley for the 22" oven that you have.

Lastly, will definitely add the chicken wire before the stucco.

Thanks for all the help David and again, not forgetting your patience with me. Much appreciated.

Regards
Oven_Man

[david s]

Re: FINALLY!!! - Start Of Building My Oven

Yes you can make the vent out of metal. Best to use stainless steel. Whatever you make it from you should insulate it, but it is the dome and floor you want insulated well. The vent only carries away the smoke. A metal vent is harder to create curves for a good air flow. With castable you can make a free form quite easily.
My trolley is 900 x 900 mm and the outside shell is 870

[Oven_Man]

Re: FINALLY!!! - Start Of Building My Oven

Yes you can make the vent out of metal. Best to use stainless steel. Whatever you make it from you should insulate it, but it is the dome and floor you want insulated well. The vent only carries away the smoke. A metal vent is harder to create curves for a good air flow. With castable you can make a free form quite easily.
My trolley is 900 x 900 mm and the outside shell is 870

Hi David S

I'll toy with both ideas and see which 1 is easier.
You know of any Refractory Castable vent designs available on the forum that's light weight and easy to build?

Thanks
Regards
OM

[david s]

Re: FINALLY!!! - Start Of Building My Oven

Design it yourself. Just build the sand form in front of your cast dome that changes its shape gently into the diameter of your stainless steel flue pipe.

[Oven_Man]

Re: FINALLY!!! - Start Of Building My Oven

Hi David

I've been looking through Vent and Flu designs. My main concern is the dimensions should not exceed that of what the oven is going to be. If it does, then I would have to increase the dimensions of my trolley and this could make it difficult to find space on a trailer or pickup truck to move the oven around.

Anyways, I came across this design (Pictures Attached) and what I liked about it was the fact that it didn't change the dimensions of the oven in terms of Length and Breadth but only changed the dimensions of the oven height as a whole, which I am not too concerned about.

What I need to question is whether such a design will have good "Draw"?

Secondly, how wide should the opening on top of my oven where the vent will be place be, so all smoke is drawn through the flu and not out the mouth of the oven?

Thanks
Regards
OM

[david s]

Re: FINALLY!!! - Start Of Building My Oven

I think this design is unnecessarily complicated, because it draws the smke up at an angle back rather than staight up. The flue needs more power to do this which requires a larger diameter and/or taller chimney. I think yo are better off with an entry that funnels the smoke straight up, gently reducing to the diameter of your flue.

[david s]

Re: FINALLY!!! - Start Of Building My Oven

Hey oven man, you've been on the forum for ages and "Finally" you still haven't done any building. It is really instructive to actually build something. How about trying a small version cast in mud, which will cost you nothing, but give you something to start cooking in and the confidence to build bigger and better. I started this way with a490 mm diam central flue set up that cost very little, worked extremely well and gave me the energy to try bigger and better. Haven't looked back. I've also shifted the original oven and given it to a friend... it still lives. It was like saying goodbye to an old friend.

[Oven_Man]

Re: FINALLY!!! - Start Of Building My Oven

Hi David

Thanks for the advice on the vent. If I do go that route, I will definitely make sure I have a wide diameter flu that is high.

Any suggestions on the height and diameter my flu should be for a 24" oven?

Hey oven man, you've been on the forum for ages and "Finally" you still haven't done any building.

Yep 100% right. I have been planning and procrastinating for far too long now.
It is time I get started. I am taking your advice and starting small and see where it leads.

Thanks for all the patience with me.
Much appreciated.

Regards
Oven_Man

[dmun]

Re: FINALLY!!! - Start Of Building My Oven

That design is used for the low dome commercial pizza ovens where the flue goes up from the center of the dome. A few concerns:

The flue as shown goes up from the inside of the dome, instead of the entry. This means you couldn't do retained heat baking. It also means that there is a chunk of the top of your dome that isn't insulated. There is some thought that this "squirrel tail" design reuses heat from the flue, but I think this is mostly not true.

Also, if you're running your project past a building inspector, there is a maximum of two thirty degree angle bends allowed in a solid fuel vent. This is to allow a cleaning brush to get past a bend. Your design has almost ninety degree bends.

[Oven_Man]

Re: FINALLY!!! - Start Of Building My Oven

Hi Guys

Its been a while since my last post.
I know many have probably thought I've abandoned this project, but I assure you, I've worked on this every chance I've had as I'm doing this at a someone elses house and only go there occasionally

I honestly didn't think this task would have been so difficult when I thought the entire building process in my head but considering doing it all alone with no ones assistance, it takes a while.

I've just filled in the 3rd piece of my dome cast so 1 more piece to go "Yippeeee!"

The first 2 pieces were quite straight forward though still a challenge when it came to getting the perfect curve and ensuring the correct height.

Just to recap, my dome is 24 Inches, 13 inches high from the centre of the dome.

Now the third piece was a little more tricky considering it would need a section left open for the front door opening of the oven. This was a challenge but I was determained to get it right. Using drawings that I made and contraptions made of wood, I managed to fill the gap of my dome cast for the opening so no cement would be filled in there when I pour cement into the cast.

I've just filled the cast and now realised that I have errored. According to what I've read, the height of the opening should be 9 inches based upon the height of my dome. I just realised my opening height is instead 10 inches.

A few questions I have.

1) Would the above opening height of 10Inches be need for concern or would I need to get it at the right height of 9 inches and is 9 inches an appropriate height for an oven of 13 inches high?

2) I've got 1 more dome piece to make and then I'm ready for Phase 2 of my project which is putting the pieces together. Initially, my plan was to get a strong steel trolley on casters manufactured and then pour over a cement slabbing onto the trolley, which will serve as my base. The oven will then obviously sit on top of this. I've reviewed my initial plan and now wish to still use the steel trolley idea but not pour over a cement slabbing as this will add weight which I am trying to avoid. Instead, I'll ask the company manufacturing the trolley for me to place on top a metal sheeting which will serve as my base and then I will put my ceramic Fibre Boards on top of the sheeting and the oven will then come ontop of the boards. Any precautions I should take or are there drawbacks with this idea?

3) I used steel fibres in all of the dome pieces (Ouch!!!! Those things poke like hell) to streghnten it but after removing each piece I found quite a lot of voids left in my dome with steel needles sticking out all over the surface of my dome piece. I've managed to remove the needles I could see and feel and I've alo managed to fill the voids though I'm still not very happy with the filling but it will suffice. Never the less, my concern is what if these steel needles have to loosen from the dome piece and fall into a pizza while its baking. Some needles were loose, I could pull them will my hand while others had to be pulled using a plier. Is these any further precautions I should take other than those that I've already taken? I run my hand of the underside of the dome piece put can't really feel any needles though sometimes they are flat and can't be felt.

Other than that, all's good. My progress is extremely slow but steady, challenging and I enjoy every bit of it. I've had tons of hurdles along the way and I've always managed to find a way around it and I'm sure more hurdles are to come, so wish me luck.

Please feel free to make any suggestions you wish. It will be greatly appreciated.

Thanks
Regards
OM

[david s]

Re: FINALLY!!! - Start Of Building My Oven

If you are one inch too high with the oven opening, it shouldn't make much difference. It will still work ok and the extra height in the door will enable you to put bigger things in anyway, as 9" is not very high.
Try scrubbing the inside with a really stiff scrubbing brush. It should remove any more needles that could be loose. Hope you used stainless steel.

[Oven_Man]

Re: FINALLY!!! - Start Of Building My Oven

Hi David

Thanks for your reply.

I will try the brush and clean what I can. I think the needles are stainless steel, not 100% sure, how can I tell?

As for the height, I'll leave it as is, hopefully all goes well, worse case if it poses a problem, I'll have to add the extra inch on the already built oven.

Any tips for the Steel Trolley?

Thanks
Regards
OM