Tims oven - early days!

[Tim F]

Re: Tims oven - early days!

Thanks for the offer! I will track down some steel and get back to you.

[Salv B]

Re: Tims oven - early days!

Hi Tim,

I caught up with progress on your build today. What a great looking oven. I really liked the idea of the arch entry into the wood storage area. I liked it so much I will probably nick your idea when I get to building mine! I love the red brick look and the matching arches. I am looking to lay my concrete slab this Friday and see how it goes from there. I will be inerested to see what you do with the chimmney and vent (I've also had a good look at Neills great work on his build)

Cheers

Salv

[Tim F]

Re: Tims oven - early days!

Looking forward to some pics of your oven!

I made quite a bit of progress today. Picked up 12 bags of Coolcast during the week, and with the help of a friend we finished insulating the whole dome. I also got the entry arch underway.

The Coolcast was quite nice to work with - it is very gritty and crumbly when wet but dries to a hard finish, almost shiny. We were running low by the end even though I thought I got plenty extra, so we added a few handfuls of vermiculite to the last couple of batches. The total thickness is 80-90mm on the sides and 120-130 on top. The easiest way to get it a vaguely consistent thickness was to use a stick with a line ruled at the desired thickness - you just slap some on, then hold the stick against it to check if it needs more.

I've been conscripted to do some other work around the yard tomorrow but I'm hoping to get the entry arch finished so I can put together the final chimney design.

[staestc]

Re: Tims oven - early days!

Nice job Tim! The coolcast looks almost like clay from the picture
Travis

[nodoubt68]

Re: Tims oven - early days!

Ok, I noticed you haven't use any ceramic insulating blanket, does the" coolcast" work instead of the blanket ? I'm just asking because if there is a way of insulating the dome without using the blanket I,d love to know. By the way , your dome looks wicked! And I agree Travis , its got a real clay look about it. Very attractive..

[Tim F]

Re: Tims oven - early days!

Thanks guys!
Yes, the coolcast is (fingers crossed) going to be very close in insulating value. The 80-90mm layer I applied should give me a total R value of around 22 at working temperatures, equivalent to 3 layers of blanket.
I've attached a couple of PDFs showing details of coolcast and superwool blanket for comparison.

[Tim F]

Re: Tims oven - early days!

Now for some pics! I finished off the entry arch, so the only remaining step is to construct and attach the chimney and fix the front edge of the floor bricks. I was surprised to see that even without the flue attached, it draws like a trooper through the hole in the arch!

After the construction side is finished, I will render the dome and the outside of the entry arch. I'm still deciding on some of the options there, having seen the dome in that clay colour I am quite taken with it. I will probably make an extra arch out of thin pieces of brick, protruding out past the sides of the entry arch, so that the render has something to sit up against, if that makes sense.

The top of the stand is going to be tiled in some large red clay pavers to match the brick, and we are still leaning towards a stone veneer for the sides of the stand. All of the cosmetic stuff will probably have to wait until after xmas though.

I'm thinking I will light curing fires till Sunday then see about firing it up for pizzas!

[Tim F]

Re: Tims oven - early days!

I have to give a big thanks to Neil for welding together my rather badly designed chimney vent last night. I definitely couldn't have got it done on my own in time for my birthday.

Today my parents and little sister rocked up with a trailer and shovels and offered to help clean up my little construction site. I decided that I couldn't let them leave without dinner after a hard days work and fired up the oven for the first time!

The pizzas came out pretty well - I think I will get better at handling the fire, and I only had prunings from our fruit trees handy to fire it with. I think some properly seasoned hardwood will make a difference too. However they were pretty delicious for a first go. I only got the camera out for the last one, which was sliced chicken and pine nut sausage, sauteed zucchini and onion, olives and rosemary. The first one, a basic margherita with fresh basil from the garden and tomato slices, cooked in under 1 minute, although the crust could have been a whisker browner.

My bases were only a very basic 2 hour ferment, it will be good to see how much better a proper overnight rise or sourdough will be!

The coolcast seems to work well. 1.5-2 hours after getting it to pizza temperatures, it started to get quite warm to the touch - around 45C on the sides and 30C on top. However there was still a bit of steam coming off it so it will be interesting to see how it goes when properly dry.

My chimney is 2.3m high, with 6" stainless flue pipe. It performed pretty well but we did have a little smoke out the front. I can see that maybe 8" would have been better but this will do. The calculator gives me a flow rate of 633.

I did get some cracks in the insulation and around the arch, but that's to be expected. I guess that is one advantage to using blanket vs the coolcast.

[Tim F]

Re: Tims oven - early days!

It seemed like a shame to waste the rest of the heat totally, so we raked some coals to the front and finished off with a couple of pancakes with cream and honey. Next step is to figure out a door so I can make some bread.

[Salv B]

Re: Tims oven - early days!

Hi Tim,

It must be a great feeling to actually have cooked some food in your oven. Congratulations!
I was looking at your pictures and was interested in your vent and flu set up. Can I ask you the dimensions of the vent opening in your arch and how you worked that out. Similarly, how did you work out the dimesions of your steel vent? I must say, out of all the elements of the oven the vent and flu part is the most vexing, even though Neill has given me some great info already to a number of questions.

It wil be a while before I get to the vent and chimney on my build, but I would like to have a clear idea in my head soon about how I will do this part. I'm hoping to sort out Besser blocks tomorrow and have my oven stand done by next weekend.


Cheers

Salv

[Tim F]

Re: Tims oven - early days!

Hi Salv,

The vent opening was designed so that I had at least twice the area of the actual flue pipe. I just made the entry 300mm deep, and after a few courses of this arch I stopped and continued on as 2 separate arches, 60 and 75mm wide at the back and front respectively. That gave me an opening 165mm deep, so then I checked how wide it would need it to be to give me the area I wanted and started the 2 arches at that point. I will do a sketch if I haven't explained that well, but I think you can see it in an earlier photo.

I made the vent to sit about 10mm outside of the opening. It was cut out of 0.9mm stainless, and I used a thin cutting disk on an angle grinder. Neil folded and mig welded the pieces together for me (and suggested a much better way I could have designed it, out of 1 piece rather than separate side pieces). To attach the pipe, we used a short length of pipe, cut flaps in the bottom and bent them out, then pushed that through the hole in the top of the vent and welded it on. The dimensions ended up being 190mm deep, 450mm tall, 190mm wide at the top of the front and back faces, and 420 wide at the bottom of the front and back faces. After cutting the base to fit snugly around my entry arch, I used 4 small dynabolts to attach it and then ran some mortar around the inside where it met the brick to ensure a good seal.

I think if I did it again I would probably go the 8" flue but I did find that if I held a piece of ply against the top part of the front of the entry arch, all of the smoke that was escaping was blocked and sucked back up the chimney. So actually this could have been solved by a slightly better arch design.

[Tim F]

Re: Tims oven - early days!

Actually could a mod please change my thread title suffix to something more appropriate like "making pizza"? Didn't realise you couldn't change titles when I started it.

Todays project is to figure out at least a makeshift door so I can do some bread.

[Tim F]

Re: Tims oven - early days!

After the third firing there doesn't seem to be any increase in in the cracks around the insulation. Holding my hand over the cracks, they don't seem to let out any more heat than the uncracked parts either, which is a relief. Now that it's all dry properly the insulation seems a lot more effective too - last night I lit the oven at 6.30, and at 10 I could hold my hand against the dome comfortably. I will post some graphs as soon as I get a decent thermometer to measure the inside and outside properly.

[Salv B]

Re: Tims oven - early days!

Hi Tim,

Thanks for the info on vent opening dimesions etc.. It was very clearly explained and helped considerably with my thinking on a solution for my oven. I should get my act together and post pics soon - have finally got the stand built and hope to have the hearth done in the next week ot two.

cheers

Salv

[Tim F]

Re: Tims oven - early days!

I've made a little more progress on the finishing touches. I made a door out of some sheet metal, by cutting 2 arch shapes to fit the door and attaching them together with a 50mm strip between them. Then I filled the middle with vermiculite and screwed on a handle. Seems to work ok so far but I am already planning another upgrade - but at least I don't have to worry about it catching fire

I also dug out what seemed like 72 tons of dirt and clay, and did a bit of a rough paving job in front of the oven. I have also installed a thermocouple under the dome insulation so the next step is to render the dome - then I can think about the work surface and finish for the base.