correct oven plans

[TapRackFire]

Re: correct oven plans

Based on those photos I guess I better not use these and keep looking for the stainless needles.

A supplier just called me back. He has the needles at $3.00/1pound bag. He says I will apply them at 1 bag of needles to 1 bag of the castable which weighs 45 pounds a bag.

[TapRackFire]

Re: correct oven plans

The castable material I picked up is called "TEX KAST HS". It is made by Refactories INC. I think I read a post of somebody using it. I tried to post a pic of it, but it is too difficult to figure out how to do it. I will try later.

[david s]

Re: correct oven plans

Based on those photos I guess I better not use these and keep looking for the stainless needles.

A supplier just called me back. He has the needles at $3.00/1pound bag. He says I will apply them at 1 bag of needles to 1 bag of the castable which weighs 45 pounds a bag.

Sounds about right.
I use 2% by weight.

[TapRackFire]

Re: correct oven plans

i had another question come up about my firebrick. I bought the 4.5 x 9 x 2.25 inch firebrick. I was told it was rated to 1700 degrees. I assume 1700 F.

A supplier I was trying to get my needles from said the bricks I bought are a "low or light duty". He said they would fail quickly over time. He said I should have bought the "medium duty" fire brick. He quoted these good 2700 F.

It is not too late. I can take my bricks back if I need to and get the right ones.

Has anybody used these "Low or light" duty bricks?

[TapRackFire]

Re: correct oven plans

I tried to mix and pour my castable this evening. I had big plans of completing
60 percent of the dome. I mixed my first bag, added my needles, and the mix looked great.

Well, I thought I had things well in hand and decided to add a second bag in the mixer and the needles. It looked good. When I turned the mixer off and started to pull the mud out of the mixer(just minutes later) the mix started to to look dry again. We added more water and it looked good again. Before I could get it out of the mixer it stated to set up. We moved pretty fast to get this chunky mess into the forms. I had to add more water and mix it even more, once it was in the forms.

I read the bag of Tex Kast and noticed you could only mix this stuff for 4 minutes and then you need to get this stuff into your forms. I will try to do better tomorrow. I hope the two bags I mixed are not lost.

[david s]

Re: correct oven plans

Only mix one bag ( 25 kg)at a time and if it is hot use chilled water. Adding more water once it has started to go off is not good. You should have it placed and vibrated before it starts to go off.

[TapRackFire]

Re: correct oven plans

Yup. I know that now. These bags are 50 pounds each. Does it matter if I mix this in an electric mixer or a wheel barrel? Also, do I need to pull this stuff out of the forms I mixed up today and throw it away and start over?

Man, I did not realize the open time on this stuff was so short.

[david s]

Re: correct oven plans

I prefer to use a barrow to mix it because you can see the mix better and the stuff sticks to the sides of a mixer too much for me and makes cleaning difficult. Also you should rinse off your tools and your barrow as any trace of previous mix will tend to accelerate the rate fresh added mix will go off. Hard to say about what you've done and whether to leave it or remove it and start again. You'll probably be ok, but don't blame me if it isn't.

[TapRackFire]

Re: correct oven plans

I expect you to take full responsibility for my mistakes. I will let you know how it goes tomorrow.

[TapRackFire]

Re: correct oven plans

Thanks for all the help and advice. I finally finished the pour!! Can I leave the finished cast material exposed to the elements before I cover it with vermiculite and portland?

I will try to post pics. Very challenging to post pics.

[david s]

Re: correct oven plans

Thanks for all the help and advice. I finally finished the pour!! Can I leave the finished cast material exposed to the elements before I cover it with vermiculite and portland?

I will try to post pics. Very challenging to post pics.

Yes, castable only needs 24 hr to cure unlike Portland cement products that need 28 days to cure.

[texman]

Re: correct oven plans

i had another question come up about my firebrick. I bought the 4.5 x 9 x 2.25 inch firebrick. I was told it was rated to 1700 degrees. I assume 1700 F.

A supplier I was trying to get my needles from said the bricks I bought are a "low or light duty". He said they would fail quickly over time. He said I should have bought the "medium duty" fire brick. He quoted these good 2700 F.

It is not too late. I can take my bricks back if I need to and get the right ones.

Has anybody used these "Low or light" duty bricks?

I bought the low duty brick and returned them and acquired the medium duty. If it isnt too late i would definitely recommend getting the better bricks.
Texman

[texman]

Re: correct oven plans

i reread the thread. Where are you using the firebrick if you are building a castable?
Tracy

[TapRackFire]

Re: correct oven plans

I layed a base of firebrick to be used as the floor of the oven. I set my forms ontop of the firebrick and poured the walls and ceiling. Did I do it wrong? It is way too late now. What should I have done?

[texman]

Re: correct oven plans

yes, move on. The main problem may be some spall (pieces coming loose) from the heat. Wotavidone is right, you can replace them in the center if needed. Sorry to give you the scare, you can use the higher duty brick later if needed.
How about some pics?