Mobile Hand-Formed Dome Oven Build

[timrj]

Re: Mobile Hand-Formed Dome Oven Build

I have been trying to read as much as I can about mobile oven builds. I hope to start one soon. (Going to try to weld up a trailer first)

I have a question about your anchors - aren't those going to act like heat sinks and pull heat right into the metal frame?

[rasorface]

Re: Mobile Hand-Formed Dome Oven Build

I am building the dome using three or four layers. The inner layer will be about 1.5-3 inches thick and will be comprised of refractory concrete. The next layer will be an insulation layer. It will be comprised of a standard concrete mix with insulation beads replacing the gravel or sand. The next layer will be a structural layer which will be a standard concrete mix. The anchors will be embedded in this layer. They will be bent to accommodate the curve of the shell. I may or may not top the last layer with stucco or some other sort of protective barrier.

[david s]

Re: Mobile Hand-Formed Dome Oven Build

For the dome insulation use vermiculite or perlite mixed with cement no richer than 10:1 When you say insulating beads I hope you didn't mean polystyrene. They will burn and melt and create nasty toxic gases. This mixture insulation layer should be around 4" thick and needs to be purged of moisture before doing the next outer layer.I find the best way is to do a layer about 2" thick then leave it for a week to dry before doing the next layer. Blanket is easier but more expensive and toxic.

[rasorface]

Re: Mobile Hand-Formed Dome Oven Build

Thanks, David. Yeah, I didn't mean polystyrene. Thanks for the drying tip. I will certainly do it.

[rasorface]

Re: Mobile Hand-Formed Dome Oven Build

I neglected to post some pictures of the fire brick layer of the floor. This was done back in early April. The grout job didn't come out as nice as I would have liked.

Yesterday, my wife and I did a trial run of hand forming the oven dome over a sand form. We used a standard 1:2:3 concrete mix for the test. I didn't take pictures of the process, but will post some pictures of the finished test.

This was very educational for us and we will do some things differently for the real thing. For example, hand forming around the door form was not without problems. A different solution is being formulated. We're so glad we did this test run.

[rasorface]

Re: Mobile Hand-Formed Dome Oven Build

We did a test build, using a standard concrete mix, to see if hand casting the refractory layer was feasible. In my opinion, it is not. The refractory material is expensive and I have little control in preventing gravity from fattening the bottom of the layer toward the floor. A form is definitely needed. In that regard, this link is inspiring: http://www.fornobravo.com/forum/f28/...rill-2207.html

[david s]

Re: Mobile Hand-Formed Dome Oven Build

If you mix the castable up withbthe correct water content it will be stiff enough to stand up vertically. It does it better than a normal concrete brew would. It can be done without an outside mould, but you can't vibrate it or it will slump. With care you can create a good dome in one piece with very few voids.

[beagleace]

Re: Mobile Hand-Formed Dome Oven Build

"to see if hand casting the refractory layer was feasible. In my opinion, it is not".......Looks pretty good to me, especially for a first attempt.

[doctorphreak]

Re: Mobile Hand-Formed Dome Oven Build

to see if hand casting the refractory layer was feasible. In my opinion, it is not".......


looks darn good to me shoot if that was refrac crete i would be cooking in it now....

[rasorface]

Re: Mobile Hand-Formed Dome Oven Build

Overkill is understating it.

Finally finished with the form for the refractory layer. A couple finishing touches, and it's time to pour.

If I ever build another one (hoping so), I think I'll use sand for the inner form. The inner form will be sacrificed after the pour. The outer form might be reusable.

[sonomacast]

Re: Mobile Hand-Formed Dome Oven Build

wow, that's a work of art on it's own. Shame to get it dirty, How is the door/entrance to be formed
? Good luck and good work.
See my build at http://www.fornobravo.com/forum/43/f...day-16182.html and http://www.fornobravo.com/forum/43/f...ild-17613.html
If I can help in any way please don't hesitate to contact. Thank you

[david s]

Re: Mobile Hand-Formed Dome Oven Build

Wow, that's hours and hours of work to make a mould. i don't think the effort is worth it for a single casting and a timber mould really takes a beating every time you make a casting, so it doesn't last too long for multiple castings.
Make sure you use some kind of release agent and vibration when you place the mix.
A small orbital sander without the sandpaper does a reasonable job for this.
Also don't mix up more than one 25 Kg bag at a time because the stuf goes off pretty quickly.Use chilled water if it's a hot day.

[Lburou]

Re: Mobile Hand-Formed Dome Oven Build

....snip....How is the door/entrance to be formed
? Good luck and good work....snip....

Sonomacast, you are so tactful.... Rasorface, you need to save that mold for me, its a work of art like David s says

[rasorface]

Re: Mobile Hand-Formed Dome Oven Build

Poured the refractory layer today with the help of my family. I screwed up on the door. I had to hack the outer later to make a void for it. We'll see how it looks when I pull off the forms. With hope, will have this the oven done during Spring.

[vertigopilot]

Re: Mobile Hand-Formed Dome Oven Build

Poured the refractory layer today with the help of my family. I screwed up on the door. I had to hack the outer later to make a void for it. We'll see how it looks when I pull off the forms. With hope, will have this the oven done during Spring.

Looking forward to seeing the results of your handiwork when you pull the mold.