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Wow, that went smokeless so quickly! Your fuel must be really dry. That thing is doing great man, you are going to have a hell of a heater there.

Yeah that stuff is super dry.

Couldn't be happier with the way the thing burns, but sure wish It hadn't cracked apart. I'm going to patch up those cracks as soon as I can find a sucker dumb enough to help me move that riser off. That thing is a beast.

Well I tore down the core and rebuilt it. The bottom eight inches are so were solid so it was just the top half I needed to redo. My form was already destroyed so I just kind of sculpted it the way I guess you do with cob and it worked. I like the way it turned out. In my research on adobe brick testing I found that if you drop your brick onto concrete and it shatters it has too much sand, not enough clay. While my core cracked (which is a sign of too much clay), it was very brittle and could be crushed in your hand, so I think maybe I was wrong all this time and I had too little clay, not too much. I pulverized the top half of the core, threw in a bunch more clay, added water and re-scuplted the top. I rounded the edges because I thought it looked cool. Once it dries a bit I'll be in a better position to see if this mix is stronger.I don't think I'll put that heavy riser back on there until the core is entombed in a strong cob bench

That looks really good, Rhett.

Yeah man, it does look really good. Good practice for making that bench too, looks like you got the hang of it for sure.

I went ahead and sculpted a riser for it. I don't know, this could be a big mistake, but the core turned out so well I thought I would try the riser as well. I don't have any steel around it for support so it may just break apart or something. This brings the proportions back down closer to standard measurements - that original riser was just humongous. And heavy. I sculpted a little bit of clay onto the back of the feed tube to better support my fuel. That seems to work great. Will try to fire it up this weekend.

Nice Rhett! I imagine it will probably crack a lot, but they pretty much always do anyway. If it stays together I think it will be great. Gravity might take some chunks off that riser as it cracks though. I wonder if it would be worth wrapping in some scraps of chicken wire or something to help hold it together? I dunno, just brainstorming here. Either way, it's pretty dang cool and seems like a pretty fun way to just get a combustion unit together to play with.

right, i wondered about wrapping it in wire or something to keep it together. you know if this does holds together somewhat it gives people an option on construction if they cant find a grease barrel, propane tank, whatever. The sculpting was a little trickier than packing into forms but not by much really. And it has the advantage I think of being able to see if you are getting good coverage or if you are creating a bunch of voids.

One thing that surprised me, the clay from the original riser was still very workable weeks after construction. I only did 4 or 5 burns of 15-20 minutes so it never really got put through the paces but I was surprised how wet the clay was so long after the fact. Having the steel skin really kept the moisture in deep inside the riser.

That's really cool, Rhett! It totally has a Dr. Suess look to it. I love that wavy natural building look and am kind of sorry I went with the hard lines of brick for mine.

As for holding up, with my old potbelly I wrapped a flexible copper water line around the exhaust and encased it. I had a hard time keeping it in place because it always expanded and contracted with the heat (less than you'll be seeing, too!). Eventually I added that flexible metal masonry mesh to it and tied it around with wire. It helped dramatically, though still needed maintenance from time to time.

Ha that's right, very Dr Seuss. That's a good way to describe it. I was thinking it looked insectoid or something. Like some kind of alien termite mound. But Dr Seuss works.

Man I have had the thing in my shop it's just not drying in there. The core feels almost as wet as the day I made it.