|
Post by petect on Feb 23, 2013 11:43:31 GMT -8
|
|
|
Post by endrunner on Feb 23, 2013 16:01:46 GMT -8
Thanks so much for the feedback! We should be ready to ship full cores in a few weeks. Our website is not up yet, maybe a few weeks away on that. We are thinking of doing a kick starter to get sales. We are happy to take pre-orders
|
|
|
Post by peterberg on Feb 24, 2013 2:17:13 GMT -8
As you know, I've always focused on the low tech. Solutions that can be made by anyone, virtually anywhere. I wonder how much of this kind of design can be done reliably with more.. neolithic/post-apocalyptic methods and materials.. You are right, I am thinking along the same lines. That's why I've tried to build one of these 6" cores out of firebricks in early spring 2012. Used a small trowel and a small grinder equipped with a 5" diamond saw. Stoneware clay and sand for mortar, clay and perlite (a lot) to shape the vortex end. All the other details were shaped out of bricks using the grinder. It took me two messy and dusty days to build a core vaguely similar to the present cast item. And another day to throw a make-shift feed tube together using the same grinder and a stick welding inverter. The riser was assembled using a hotchpotch of small pieces of vermiculite board, some screws and several feet of steel wire. Did work nicely, smokeless in about 8 minutes if I remember correctly. Just the core, nothing else and fired outside a couple of times. No measurements of course, forgot to take pictures. I'd need the bricks for the batch box project so I tore it down a week later. I'd think this won't count as neolithic/post-apocalyptic methods. ;D One would need electricity, reasonable advanced tools and craftsmanship of at least three disciplines. Not to mention an intimate knowledge of the core's innards.
|
|
|
Post by Donkey on Feb 24, 2013 8:14:02 GMT -8
Perhaps a form could be made with scrap cardboard, a home-made clay/sand/ash mix poured in (or packed in), then burn out the form.. Or a rough chamber built with high fire adobes, then hand sculpt internal details using the same mix.
I've often wondered if forms for a more modern heater core could be folded out of cardboard (likely waxed cardboard), which would double as the shipping container, to be burned out after assembly. This kind of form would complicate some things, like getting the cut outs, folds and tabs accurate enough; it can simplify a little as well, since the form is burned out, under-cuts and other difficult shapes would be possible.
|
|
|
Post by endrunner on Feb 24, 2013 8:53:06 GMT -8
IMO one of the problems with most handmade RMHs is the use of firebricks for the burn tunnel. Firebricks are great as thermal sinks, great numbers, 2x even granite for heat storage. But that's just the problem, it seems in the combustion zone, you don't want heat sinks, you want insulation properties, to get and keep combustion as hot as possible.
So any hand crafted burn tunnels need to be toward the ash perlite side with as little fire clay as possible.
|
|
dvawolk
Full Member
DSR2 125mm open system (actual project)
Posts: 255
|
Post by dvawolk on Feb 24, 2013 11:01:39 GMT -8
I am just drying the clay sand mix. I did the core with styrofoam with dust tape around. The core was dissolved with nail polish remover (acetone). Acetone dissolves styrofoam but does not dissolve dusc tape.
|
|
|
Post by Donkey on Feb 25, 2013 9:09:52 GMT -8
IMO one of the problems with most handmade RMHs is the use of firebricks for the burn tunnel. Firebricks are great as thermal sinks, great numbers, 2x even granite for heat storage. But that's just the problem, it seems in the combustion zone, you don't want heat sinks, you want insulation properties, to get and keep combustion as hot as possible. So any hand crafted burn tunnels need to be toward the ash perlite side with as little fire clay as possible. I tend to agree.. However, the expense of high tech materials, the skills to build the forms and cast a good working model are not available to everyone. My personal mantra is accessibility and user friendliness. To this end, some compromises can be made. I think that for a lot of people, it's worth a slower take-off to have a stove of this quality for next to nothing. Otherwise, I agree with you completely, EVERYTHING should be as well insulated as possible.
|
|
|
Post by endrunner on Feb 25, 2013 14:03:36 GMT -8
We agree!
|
|
|
Post by matthewwalker on Feb 25, 2013 14:13:15 GMT -8
This is a great discussion everybody. I whole heartedly agree, and feel that this info isn't really that well known out there. Good stuff.
|
|
|
Post by stephenson1 on Feb 26, 2013 4:57:06 GMT -8
That is truly beautiful. I look forward to hearing about burn tests. Is the vermiculite board durable enough to serve as a heat riser in the long term? If so, where to you get it? I'll be rebuilding my rocket oven in a few weeks and it would save a lot of grief stacking firebricks.
|
|
|
Post by endrunner on Mar 12, 2013 12:43:52 GMT -8
Here are the latest pictures showing the 8 and 6 in versions side by side. The 8" is a MONSTER casting. It weighs over 130 lbs. The 6" weighs 60 lbs. Attachments:
|
|
|
Post by endrunner on Mar 12, 2013 12:45:14 GMT -8
from another angle Attachments:
|
|
morticcio
Full Member
"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
Posts: 371
|
Post by morticcio on Mar 13, 2013 2:34:38 GMT -8
Here are the latest pictures showing the 8 and 6 in versions side by side. The 8" is a MONSTER casting. It weighs over 130 lbs. The 6" weighs 60 lbs. Very nice! Did you use an off-the-shelf castable or your own recipe?
|
|
|
Post by endrunner on Mar 13, 2013 5:54:35 GMT -8
We use a commercial insulative castable rated for 2300F. For a commercial product we need to have the materials certified.
|
|
|
Post by matthewwalker on Mar 13, 2013 10:31:54 GMT -8
Those look fantastic! Very nice work.
|
|