Core mould done

[mannytheseacow]

That's looking really good, Rhett! I just copied the code and pasted into youtube's search box and your vid came right up.

Don't sweat the cracks. Look back at my 6" build and you'll see mine split right in half, too. I pasted it back together with a little wet mix and it's been fine once encased in the bench.

Man, right after I built mine I was sold on doing just what you did with elbows. I'm really excited to see how you like this down the road. Having gone through it all now it seems like I'll just continue with plywood core molds in the future, because yeah they shrink a lot and the plywood burns away fairly quickly. I like keeping that fire and ash down low at the feed too and not in the burn tunnel. Anyway, I really like what you did and can't wait to see how it works for you.

[matt walker]

[Rhett]

Oh I see, you have to put the full url in, not the video id. Thanks for the tip!

[Rhett]

Manny - yeah, I already think I am not going to like the elbows. Maybe the elbow under the riser is a good idea, but the elbow on the feed tube side kind of causes the sticks to angle in rather than stand straight up and burn down into themselves. I't not great. If the feed elbow burns out I will pull it out and dig out some of the core to flatten the bottom there. Either that or rig up some hoops to keep the taller sticks standing up straight. That would work. If I do the steel enclosure for the shop heater, then I thought maybe welding a little hopper out of some scrap expanded metal would make sense.

Matt - yeah, I think there is the possibility that some of that black smoke was from some grease or something on some of the wood I was burning. Or maybe on the stove pipe? But that was new so maybe not. I want to get a good long burn going during the day with the cracks patched and see what happens. It's not perfect but yeah, it seems workable. I mean, the thing produces heat so at the end of the day that's something!

[Rhett]

Just noticed you said "the core might still be wet". Yes, it's terribly wet still. So is the riser. Is that a factor in the cleanliness of the burn? I guess that could keep temps lower than they would otherwise be so that would make sense...

[matt walker]

Yeah, wet is a huge drag on the system. They get progressively better as they dry. If your stove pipe was new it was for sure smoking, they are coated with paint that burns off and smokes quite a bit as it does. It doesn't actually burn away, the pipe will still be black, but it like, cures/burns off some stuff on the first burn.

Interesting about the core made from elbows, the sweep in the feed being a pain makes sense. You know, my core has that "atrium" off the feed for the window, and I am constantly sweeping the larger chunks and coals back there, away from the burn tunnel, to keep them from building up. Might be something to think about for your next cast Manny, especially with the hard, coaling, wood that you have there.

[Rhett]

Yeah I burned it again last night - crystal clear. Already so much better and I think it will get better still. There is still a lot of wet clay left. Man, I used too much clay. I am sure of it. The riser is breaking apart too now. When it comes to mixing, vermiculite != perlite. I used 2:1 verm to clay and I really think it was nowhere near enough. I am afraid when the pipe burns out the riser is just going to fall to pieces if I move it. So I need to get it placed where it is going to be and not touch it. It's insulating good, the propane tank outer shell doesn't remotely get warm after 30 minutes of burning so that's nice. Not too worried about the core either, I can patch it up and then brace with cob or steel as you said.

It's performing beautifully as far as I can tell, even with the wet clay left. I think that smoke must have been the stove as you said, I didn't realize new pipe would do that. One thing that surprises me is how easy this thing is to light. It wants to be on fire.

So adding up my materials, I have spent $75 on clay and have two of 5 bags left so that's $45, I spent $35 on two buckets of furnace cement and used that. I spent $70 on 8 cubic feet of vermiculite and have used about 7 of that, let's call it $60. I used about $3 worth of fiberglass. $14 for the riser stove pipe and another $12 for the elbows. So all in I am at $170. Not bad for an 8" system with a massive 47" heat riser and 3" of insulation all around it, but I really think it could be improved. For one thing the perlite costs the same and I am convinced I would have used half as much, I'll have to pay closer attention to the labeling next time. That would have saved me $35 and resulted in less cracking. I shouldnt really call it cracking, mine is breakage.

So now I am researching cob to see if it is a good option for me for using this thing as a firepit/bench. I have a mountain of soil I excavated when I built my house. I am going to do a soil test to see how usable it is for cob.

[matt walker]

Cool man, great little wrap up of the core so far. As for the cob outdoor system, the thing with the cob is you can agonize over the soil test, the suitability of outdoor cob, and so on, endlessly. I suggest just diving in one afternoon and covering up a little half barrel bench, or a short piece of flue pipe you cover up with some mud. Don't worry too much about the details, just get muddy. You'll learn more in an hour and develop a whole lot of confidence and concepts that you didn't think of before you started playing with it. It's really, really liberating as a material. I had so many questions and perceived issues, and once I was muddy it all just faded and I was able to build shapes and solutions(particularly the exhaust transition area, barrel to flue run) I could not have conceived of prior to experiencing what was possible with the material I had on hand. So yeah, just go make a bucket of mud and play with it, don't overthink it.

[Rhett]

Well said. I think I will do that.

[Rhett]

Second burn video showing lighting and clear smoke. Don't be a killjoy about my clear exhaust not being 100% thermally efficient Matt. Party pooper.