FINALLY!!! - Start Of Building My Oven

[david s]

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

There is not much strength in vermicrete.If you want strength then use standard concrete. As a compromise you can make a lightweight concrete 4:3:1 vermiculite, sand, cement. Although it will be around half the weight of standard concrete it will also probably be around half the strength.

[Oven_Man]

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

Hi Guys

Alot of progress I've made over the past few days.
I've managed to lay the floor, added a layer of Vermiculite (Daivd S Ratios - 4 Vermiculite + 3 Sand + 1.5 Cement (Decided to go with a little more strength)) and around the vermiculite I filled all the spaces with Portland Cement.

All looks good, no real problems experienced. I was presently surprised that the vermiculite was quite easy to work with however after completing; I found that Vermiculite is quite sandy and loose even after it drying. I was considering adding a very very thin layer of cement but not sure what cement to use since the dome will be directly on this layer so it needs to withstand the heat. I have some Mortar Mix, Refractory Cement, and Portland. I will just plaster the layer on just so it's smooth because the current vermiculite mixture is not very smooth like I expected it to be. Any Suggestions?

Other than that, I'm now ready to place the casted dome pieces on the slab and begin joining the pieces together. I won?t even think about saying I?m close to completion because I?ve said that soo many times yet I see myself far from it so all I can say is I?m doing well and hope to continue in my stride.

David, one concern just popped in my head. Will the Vermiculite Mixture mentioned above be able to handle the direct heat of the oven (Dome will be sitting on top of the Vermiculite)? I?m just a little afraid of it cracking or worst of exploding because of the heat. Just to recap, beneath the vermiculite mixture is a 4? layer of Ceramic Board so I?m happy with that insulation and still stand by the fact that the vermiculite is not for insulation but rather strength so it can handle the weight of the Dome. By the way the Vermiculite is 1" thick

I look forward to hearing from you guys.
Thanks
Regards
OM

[Gulf]

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

Hi Guys
I found that Vermiculite is quite sandy and loose even after it drying. I was considering adding a very very thin layer of cement but not sure what cement to use since the dome will be directly on this layer so it needs to withstand the heat. I have some Mortar Mix, Refractory Cement, and Portland. I will just plaster the layer on just so it's smooth because the current vermiculite mixture is not very smooth like I expected it to be. Any Suggestions?

OM

The weekend that I poored my vermicrete layer I ran out of the course and the only source was closed. I had to pour the top 1/2" with a fine horticulture grade vermiculite. I was pleased at how smooth it turned out.

EDIT I did not read this as closely as I should have. The part directed to Dave says that your vermicrete is above your 4" of calsil and only 1" thick of vermicrete. Mine was 4" vermicrete/2" calsil in reverse order of what I just read. Maybe a thin coat of fine vermicrete could still help with the surface.

[david s]

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

The vermicrete will handle the heat ok. You can render over the vermicrete that projects past the outer shell once you have finished. I use the same mixture that I use to do the outer shell ie. 4:1:1 sand, cement, lime

[Oven_Man]

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

Hi Guys

Thanks for the responses. I'll go ahead with the suggested advices.

Keep you guys posted.
Regards
OM

[Oven_Man]

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

Hi David
Hope you are well

I'm on Phase 3 of my project as I have successfully joined my domes. I had quite large gaps in between each casted piece but I managed to fill the gaps with refractory.

Now, I'm onto my Vent. I am still torn with my current vent design.
I have attached pictures of my oven with the mould design of my vent. I attached a picture similar to this once before but it was actually before I joined my dome Pieces. I've taken plenty of pictures so I'm sure you'll be able to make some sense of exactly where I am at with this design.
The design in essence is fine but I have one problem. The vent protrudes out too much from the entrance of the oven. It sticks out by +8".
I'm just concerned its gona make accessibility to the entrance of the oven difficult, what do you think?
The height of my vent is about 7", I'm thinking this is a little high - it just looks too bulky - should i reduce to about 4" or so.
My next question is how high above the entrance of the oven should it sit. My ovens entrance is 9" and I was planning on placing my vent exactly at 9" but I really need some help with this.

Lastly, I have revised my entrance a little bit. My current entrance is 10" high but I will bring that down to 8", and the arch of the entrance will also decrease in size proportionately. After reading a post by James, the idea is to keep the width of the bottom of the entrance at 16" and close in as you get closer to the top, thus offering better heat retention. Let me know if I am on track with this theory.

Thanks.
Regards
OM

[Oven_Man]

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

Sorry, I couldn't fit all of the pictures on 1 post so here the rest.
Thanks

[david s]

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

The best advice I can give you is to look back on your thread at my post from
6-15-2011 and look at pictures which detail how you can achieve a shallow entry and good funneling to the flue pipe.

[Oven_Man]

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

Hi David

Thanks, I've relooked those posts and now that my cast pieces have been put together, your vent design makes even more sense. In fact, your design will fit my oven perfectly.

It look as if you created a form of some sort upon which you poured your cement into. Am i right?
If so, I'm curious to know how do I go about making my own vent very similar to your. The curves and shapes in your vent look perfect but i just cant image how to do this. Please help?

Thanks
Regards
OM

[david s]

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

Cut a piece of timber(about 1'' thick) that will be the space for your door. Make sure you put a couple of wooden wedges under the bottom so it can drop a little for easier removal. The rest of it can be done in damp sand (10%water) You then simply trowel the castable over the sand to create your casting.I make buttresses on the sides to increase strength, but alternatively just make the whole thing thicker.When the casting has set (24 Hrs) remove the timber door mould and the sand.

I made a fibreglass mould for mine but that is too much trouble for a single casting. Just pile the sand up right where you want the casting, in front of the door mouth, then you won't even have to move the vent piece, it will be cast in position.

[Oven_Man]

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

Hi David
Hope you doing well.

I am at the tail end of my oven. The Vent is casted and in place although it didn't come out exactly how I wanted it to, but I'll leave it and decide how to improve it later - I just need to see this oven Fired Up.

I just wanted to run something pass you. I have a full pocket of Mortar which I really didn't need but just decided to get it in case. I may need to fill in gaps here and there on the oven and was wondering if I could mix the Mortar with Some Left Over Gravel I sieved out from the Refractory Cement a while back. I have a little refractory cement which may not be enough and I'm just trying to make do with whatever I have instead of incuring expense.

How would you suggest I go ahead and do the mix and get the most out of the left over material I have?

What mix ratio do you suggest I follow for my Vermiculite that I'll be placing over the Ceramic Blanket?

Thanks
Regards
OM

[david s]

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

For the vermicrete over the blanket don't waste your refractory cement just use normal cement in the ratio of 10: 1: 3.5 vermiculite, cement, water. If you are using the stuff to fill in gaps in the dome you could use it as is or add the aggregate back in, but it will be a stronger mix if you don't.

[Oven_Man]

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

Thanks Dave

Do I need to add Sand to my Vermicrete Mix, atleast for some stregnth?

Any tips on how to make use of my Mortar?

Thanks again
Regards
OM

[david s]

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

No, don't add sand, you don't want strength in this layer, only insulation.

[Oven_Man]

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

I see, will remember that.

I plan to add a 1" layer of Vermicrete and not add anything ontop of it for now.
I'll fire up the oven like this and use it for a while and see how things go.

I'll add stucco in a couple of months once I'm happy with the functioning of the Oven.

Will it be OK to the above?