Homebrew 3:1:1:1 density vs refractory cement?

[Freelance]

Hello,
I'm doing some calculations on material need, weight and cost and I would appreciate it if someone could advise the final density of the homebrew mix. Even better if someone could advise on the final weight of 50mm thick and 700mm inner or 750mm outer dome diameter, I would rather cast it on another location and move it over later on.
Also according to preliminary calculations seems that the homebrew will be much cheaper than the ready-made refractory cement from the shelf, is there any reason why some people choose to use refractory cement vs homebrew for the inner core?

I'm also reading about stainless steel needles and fibers to be added to the homebrew. What kind of ratios and which kind of fibers?

[4stroker]

Hi Freelance, where are you located?

I'm in Australia, and I have a similar discussion going over in this thread:

https://community.fornobravo.com/for...aterials-in-nq


Have a look at the 7th post where I have worked out my weights etc of homebrew materials, however i am waiting on confirmation that i have gotten it correct.

To work out your dome volume you need the formula for volume of a sphere:

https://www.mathopenref.com/spherevolume.html

Subtract one sphere from the other, and divide by 2 (as you're only building half a sphere).

For your dimensions I get a dome volume of 0.045m3, or 45 liters.

Note, this doesn't account for the volume of mix required for the transition to entry etc, but then you essentially take a portion of the sphere out for the entry anyway, and on my build at least (very shallow entry) i have modelled it in CAD and have found that the two essentially cancel each other out.

Also just note that at 700mm inner diameter, and 50mm thickness, your outer diameter is 800mm, not 750mm.

[Freelance]

Thanks, I'm in Sweden, I've calculated the similar size and given the density of around ~2kg/L I assume that the dome will be less than 100 KG which should be manageable by two persons and move in-place after casting. I'll continue my research on the fibers and SS needles before I start my build.

This forum is great and fun to read!