Looking for acurate Rumford measurements

[seamad]

Re: Looking for acurate Rumford measurements

seamad,

would be interesting to share notes on this. I have been experimenting with different heat resistant mixes myself over the years. A lot of the stuff that is readily available in the US is just ridiculously expensive over here (or not available at all)

Casting the throat can be a challenge in itself. The best approach I have found so far is explained here:
Richards Rammed Earth
Just build the fireplace out of brick and make the curved section of the throat out of ferrocement (chickenwire and rebar)
A mix of 1:2 portland cement/plaster sand on three layers of chickenwire is surprisingly heat resistant.


I have tried this myself (adding 0.5 part lime putty to a 1:3 portland/sand mix to make it easier to sculpt) and so far so good.

Here is some research into the fire resistant behaviour of ferrocement:
www.doaj.org/doaj?func=fulltext&aId=1465260

here is another forum discussion about alternative throat designs:
Casting Rumford Throat - Masonry - Contractor Talk

As for casting, I have not tried this yet but three sources on the web seem to confirm that this is the best homemade recipe:
Homemade furnace refractories
Making DIY Refractory For Your Foundry Furnace.

2/1.5/2/1.5 (fireclay/portland/silica sand/perlite)

But, in the examples given (foundry from melting metal) this mix is cast into a container and the final form is thick and solid. The throat on a rumford has thin, curved walls, so it can't be to brittle.

I would probably stick with the ferro cement, or, add some reinforcing metal mesh to your casting.

Let me know how you get on.

Cheers,

thijs

Bit of a thread hijack sorry.
Had a look at the chicken wire method awhile ago and thought it looked pretty simple.
For some reason my IP address is banned for contractor talk and I can't sign up, have tried a few times ans sent them a coupke of emails with no response.
Just started cutting some bricks for my wfo. Haven't finished the new deck for them both yet, missus wants it done for xmas
Will keep you up to date.
cheers