I've had another epiphany. It may have already been done but it's new to me. I was thinking about the possibility of casting the J tube in refractory cement. Risers could also be done in this manner. Nothing new about these ideas.
In order to ensure that new builders get it right, a mould could be shipped to prospective builders. It would be sort of a plug made from either Styrofoam or a stiff, waxed form of papier-mâché that could hold its shape during the process, similar to the stiff paper towel cores used in commercial applications. It would form the inner shape of the J tube. I can imagine any number of deviations from straight lines designed to cause turbulence, direct flow or for any other purpose. Since the plug only needs to be designed once and then replicated many times it makes sense to incorporate whatever is considered best practice. Probably just smooth but the possibility exists for a multitude of contours. Papier-mâché models could be made so that they ship flat. They would assemble according to instructions. All lumpy joints and fasteners would face the inside so that the finished product would be smooth after the mould is burned out.
After the cement is set and cured the plug could be dug out in the case of Styrofoam or after a few puncture holes are made it should be easy enough to burn the stiff waxed cardboard type. With most molding processes we need to compromise the shape of the artifact being produced in order to extract the mould. But this could allow for any shape imaginable much like the lost wax process used in bronze casting.
Artists who muck with plaster of Paris have probably already worked out many of the mould making details.
A mail order business could be developed around this concept. Customers could order any number of different models and shipping costs would be minimal since were talking about very light items.
Commercial installers might also like to use these plugs. I could see casting several different models in advance and then moving them using a furniture cart from shop to point of use. The plug could be burned out before shipping. Since this would be a finished, cured J tube I'll refer to it as the dry process. In referring to customer built units which are cast in place we'll refer to that as the wet process.
For the wet process I imagine the installation process would go like this. A bed of refractory cement would be laid out and then the form would be set into it and leveled and tweaked until in perfect position. Then the refractory mix could be globbed and pressed into position in the same manner that one would apply cob to a wall. The exterior could take any shape desired provided adequate thickness is achieved.
In the dry process the installer would show up with the finished J tube strapped to a furniture cart. It would be set on a foundation of firebrick or cob. A preformed riser could then be slipped over an interlocking lip. From this point on, the mass heater would be built in whatever manner is chosen.
It is probably a little too early in rocket stove development for this to take off immediately but if building code approval were to happen it might very well call for some sort of standardization. Anyone who comes up with a unique model could license the mail order outfit to market it. Some sort of cooperative could market for all of its members as this would be much more efficient than 50 of us competing to sell plugs on the Internet. I'm willing to consider manufacturing these plugs and shipping them worldwide. If we managed to get huge volume we could set up manufacturing in India where there is a long tradition of producing handmade paper products.
Of course heavy, manufactured J tubes could be shipped around the world as finished units. The whole idea of my home casting idea is to greatly reduce shipping costs and to prevent shipping damage.
I'm sure there are dozens of kinks to be worked out of this plan but it's not rocket science
And that's what happens if I wake up at three in the morning and can't sleep. I come up with grandiose schemes designed to save the world Thank you: the mad scientists Dale
With the refractory cement, the options I've looked at were either a wooden or other relatively soft mold material that you would pour a wet cement slurry into, or a metal mold that could handle the forces involved with hydraulic pressing - you put the refractory in the mold then apply enough pressure to bond the refractory.
For me, the hardest part (besides affording all the supplies I want) is firing the initial parts. Once I've made enough, I could make a rocket stove powered kiln to fire the rest...
"Instead of Pay It Forward I prefer Plant It Forward" ~Howard Story / "God has cared for these trees, saved them from drought, disease, avalanches, and a thousand tempests and floods. But he cannot save them from fools." ~John Muir