|
Post by slowfood on May 2, 2012 20:57:49 GMT
There is a lot of water in the insulation mix, However I was thinking, I actually completed the oven itself last summer and it has been sat on the bench in a well aired dry garage so do you think I would have lost a lot of moisture over that time? I don't see why not
|
|
|
Post by cannyfradock on May 4, 2012 7:32:31 GMT
Yes, I agree with you, but only you (by seeing the concrete start to dry out...or by touch) will know if it still holds any water. It's just natural that if there is water inside the concrete and you heat the concrete up the water will expand and if it can't evaporate it will just push the concrete until a crack appears.
We had a few people on the old forum telling us of buying modular ovens from e-bay which cracked on the first firing. This was probably a mixture of water retention in the dome......and the product being too fresh. The normal curing of cement based products only starts after 7 days........
Terry
|
|
|
Post by slowfood on May 5, 2012 5:13:54 GMT
I left it in the mould for many weeks before I struck it, Somebody on the fb forum tried telling me that the refractory concrete can be struck the next day without problem but tbh i don't believe him. I don't want to take any chances with this oven! It's now a part of the family
|
|
|
Post by slowfood on May 5, 2012 5:51:44 GMT
The oven itself is based on this fb oven www.fornobravo.com/residential_pizza_oven/pizza_oven_specs/premio2g110.htmlBut followes rules I found on the internet, the height of the interior dome is 90% of the radius of the oven floor? The Door opening height is 63% of the dome height? The area of the flue is 10% of the area of the door opening? The ideal door is 22" wide at the dome? The flue should be 10% (area) of the area of the doorway the ideal floor is 2 1/2" thick? My Oven The Oven floor is 1050mm in diameter (41”) The dome height is 472mm (18.5”) The doorway is a semicircle 558mm (22”) wide 297mm (11.6”) High (225.2"square) The final Flue is 8” in Diameter (50” square) The walls and floor are 3" thick Insulation consists of 2" ceramic blanket and 2" insulated concrete (Slightly thicker on the top)
|
|
|
Post by slowfood on May 7, 2012 19:05:52 GMT
Ceramic blanket 1" all laid over the oven but doubled on top of the dome for extra insulation, then covered with 25mm mesh tied with stainless steel tying wire and then the whole oven is secured and held together by steel rope and turnbuckles. (All the joints were given a bond of fire cement also as an extra precaution) Attachments:
|
|
|
Post by slowfood on May 7, 2012 19:10:14 GMT
Now here I have finnished the Vermiculite concrete insulation, 25kgs of cement per 100 litres of vermiculite, See the sections of mexh around the base, These are connected to the previous layer of mesh to take the second layer of mesh (For K-rend) Attachments:
|
|
|
Post by slowfood on May 7, 2012 19:16:42 GMT
An 8" stainless steel flue. I cast the flue above the porch in refractory (See the previous photo's) Slightly bigger to take this. It sat in perfectly (I was worried) It is held in with fire sealant and fire cement, The Flue protrudes out of the trailer roof some 150mm and now is wearing a Chinamans hat cowl, Again the flue is sealed with fire sealant (Like mastic) and fire cement, It drawes better than I ever expected, My other ovens have smaller flues but from now on it's going to be 8" Attachments:
|
|
|
Post by slowfood on May 7, 2012 19:19:51 GMT
See how well the flue design works, I was amazed how clean the outer arch is, spotless Attachments:
|
|
|
Post by slowfood on May 7, 2012 19:24:42 GMT
Here is the basic shape of the flue, I covered the whole thing in car filler and shaped it to be smoother and flow better (Rather like porting an engine) Attachments:
|
|
|
Post by slowfood on May 7, 2012 19:30:08 GMT
Here is the beginning of the design, The finished article actually had the shoulders swept up into the round flue for better flow and to keep the area , I set out to design a flue which would not demand a huge porch but maintain the same area (50"2 if I remember correctly) but also not intrude into the thickness of the dome, A lot of sleepless nights went into figuring this out Attachments:
|
|
|
Post by slowfood on May 7, 2012 19:33:41 GMT
I had some tools out so decided to make a temporary door but it seems quite adequate so no doubt it'll be permanent Attachments:
|
|
|
Post by slowfood on May 7, 2012 19:37:04 GMT
The ceramic blanket is sandwiched between the 2 ply faces, The bottom ply is simply to stop the door from falling over, Attachments:
|
|
|
Post by slowfood on May 7, 2012 19:41:28 GMT
The door has now had the face skinned with steel plate held with fire sealant and also the edge is sealed with adhesive metal foil tape. Just need to file the edges,strip the paint, stain, varnish and add some handles. Attachments:
|
|
|
Post by slowfood on May 18, 2012 10:39:07 GMT
Here you can see the base, 2" of insulating vermiculite concrete on 3 " of regular concrete on 1" marine ply with reinforcment around the perimeter only, I figured there won't be enough heat around the exterior to cause damage, It has been fired to max heat and no problems (My 1st oven blew a big chunk of concrete out of the base years ago as I had put reinforcement in it, luckily it was an easy repair,) Don't underestimate the need for a lot of insulation under the floor. Attachments:
|
|
|
Post by slowfood on May 18, 2012 10:46:54 GMT
Now covered in K-rend silicone waterproof anti crack render, finished the oven at last just cosmetics to do. The oven from inside out consists of 3" refractory concrete 1400c. 2" of ceramic fiber blanket. 1" galvanised chicken wire held with stainless steel tying wire. 2" Vermiculite Insulating blanket another layer of chicken wire (1") and finally a thick layer of K-rend (75kgs) Attachments:
|
|