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timrj 07-28-2011 12:19 PM

Casting oven - question about making pieces/joints
 
In reading some threads to research for making a mobile oven (on a trailer) I came away with the following:

- Building the Pompeii for mobile/trailer use is not recommended (though some have done it - specifically for cracking/strength and weight issues)

- cast oven seems to be a generally recommended way to build a mobile/trailerable oven

- No one seems to have a perfect solutions for securing the oven for transit (other than tie-down straps that get removed after movement)

- Joints in the casting are desirable

So - not having every done masonry or casting I am wondering how the joints are made/different pieces cast. The joints I see on the commercial ovens and the ones that are home-made seem to be something far better than just cut right through. How does one form the cast and/or make the cuts/joints?

Right now I am planning the trailer - hoping to weld one with 3500lb axle.

Thanks
Tim

Lake lover 08-19-2011 03:39 PM

Re: Casting oven - question about making pieces/joints
 
How's the trailer build going ?

Ok I have no built an oven yet. trying to source materials id a great pain around here.

but I have done lots of casting and mold making.

To make a " Keyed mold" you would be best off making a shape such as a tounge and grove joint. This can be designed into the mold or cut in later is you use the as the piece poured as the next part of the model. Hope that makes sense ?

But you must consider a "draw angle " so the pieces can be removed and reassembled.

You want a shape that is less than 90 degrees to avoid high friction from the mold to the cast part. Radiused edges are a must, easier to fill when pouring and less prone to chipping.

How were you going to rejoin the parts ?

If you need more help let me know.

I am getting a local building wholesale to look at a castable refactory up here. Hoping not to break the bank ????

Trying to seperate the casting pieces will reqire some kind of seperater / release material.

david s 08-19-2011 05:09 PM

Re: Casting oven - question about making pieces/joints
 
For a one off casting it is much easier to do it in one piece over a sand castle.

Lake lover 08-20-2011 09:25 AM

Re: Casting oven - question about making pieces/joints
 
Quote:

Originally Posted by david s (Post 119314)
For a one off casting it is much easier to do it in one piece over a sand castle.

I guess it depends on how your mold is made and the finished weight.

In an Ideal world I think one piece is best, but you should know the working time of what you are pouring, so you don't get cold joints in the pour.

If working over a sand core what will you use as an outside mold ?

david s 08-20-2011 09:47 AM

Re: Casting oven - question about making pieces/joints
 
With this method you don't have an outer mould, you just trowel it over the sand castle, covered with wet newspaper. Dig out the sand from the door after the castable has set.you can't vibrate the casting, but with care you can avoid getting voids.

Lake lover 08-20-2011 03:47 PM

Re: Casting oven - question about making pieces/joints
 
I was wondering about that.

For some reason I thought that when they talk about " Castable " I think of something that can get poured into a mold and flow into place.

But would that me a weak mix if it was made to flow ?

I know when we pour concrete foundations into ICF 'S The mix is made to go thru a pump truck. But they have concrete additives to plasticize the mix.

What wall thickness are you trying to get ?

david s 08-20-2011 04:22 PM

Re: Casting oven - question about making pieces/joints
 
The stuff needs to be made up into a stiff mix. Exceeding the manufacturers recommendation for water quantity will compromise the strength of the resulting casting. Made up to the correct amount of water produces a workable mix that will stand up vertically. The stuff becomes more fluid with agitation or vibration, a quality known as thixotropic (I love that word)

Dave


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