My little J

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My little J

Postby Bobwieser » Thu Feb 19, 2015 12:43 am

I got some over stock " Delta T Crete Block mix" from Smart Ceramics for $15.00 per 30# bag. It looks like it has lots of vermiculite in it, it's max service temp is 1600 F and the density is 23# per cu ft. I figured it's good enough to experiment with for a 6" J. As I was building my mold I asked myself 2 questions, What would Mat do, ( he would be done and be cleaning the mud off by now) , What would Peter say, ( it's your heater please build it and share the results). Mat and Peter I hope I got your expected replies correct. I did deviate from the norm because I used what was on hand. Total mix for the core and riser was 90#. Here is the wood mold for the feed, tunnel and bottom of the riser.
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I used a 12" duct with 6" coffee cans to form the riser
It has a crude tripwire. I fit it into a piece of duct trunk that was to be thrown away. Here is the parts after mixing and lightly packing.
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The drying did test my patience and after 4 days I burned out the inners of the mold.
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I have a thin sheet metal P channel.
I put a drum and connected a chimney to it I am shocked that it lights with 2 pages from a magazine, drafts wonderful, lots of heat and goes smoke free in short order.
The material is rather fragile but strong enough so long as you don't jam wood into the feed. It's light enough at 45# per piece to be some what portable. And the base stays cool after hours of burning. There is 4.5" under the core. Total cost $ 45.00 plus dumpster diving.
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Re: My little J

Postby peterberg » Thu Feb 19, 2015 10:57 am

Yes, my reply would be something like that. One advantage of a really soft refractory: it's quite insulative. The max service temperature is at the low side of things, but for experiments it's way better than an all-steel J-tube. When the feed tube is wearing out too quick, a short piece of square metal tube would solve that. It would burn away of course, but it's easy to replace.
regards, Peter
+52° 1' 47.35", +4° 22' 57.60"
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Re: My little J

Postby Bobwieser » Thu Feb 19, 2015 11:36 am

Thank you for the reply Peter. I knew the max temperature was low especially for the riser. I figured if it's rated 1600F there is some overhead in the rating. The riser is the same size as the 6" batch I posted in "My first casting". I plan put the riser on that one to see if it improves the secondary burn by heating up faster.
I did put small ceramic wall tiles in the base of the feed of the little J to combat erosion there. I removed them because it seemed to cause some occasional light smoke back from the feed, not acceptable.
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Re: My little J

Postby matt walker » Thu Feb 19, 2015 3:38 pm

Very cool Bob, I'm envious of the refractory score! I would for sure build with it and see how that rating matches real world use in a rocket. I expect it will show some wear but generally hold up well enough to function for quite some time, regardless of little pockets and cracks and crumbles.

I'm encouraged to hear about your tile in the feed experiment. I tried the same thing way back when I first cast my home J, and had the same experience which led me to favor insulative cores. Nice to get some confirmation.
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Re: My little J

Postby mannytheseacow » Fri Feb 20, 2015 3:24 pm

Cool stove, Bob. Thanks for sharing that. Any plans to encase it or just built for fun?
"Knowledge is power. Arm yourself."
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Re: My little J

Postby Bobwieser » Fri Feb 20, 2015 4:22 pm

Manny, my original plan was to make it to use outside. I am heating my basement with it for now, just instant heat from 1) 55 gallon drum. For outside use I'm thinking of putting a 10" high ring of 1/4" SS hardware cloth on top of the riser with a metal top saucer from a broken patio heater over that, no drum. My hope is that it will provide radiant heat from glowing hardware cloth. Just for fun.
I have my 6" batch in the basement too, it has a 2nd drum attached. I have to use a fan for draft because my exhaust goes 16' horizontally outside. It heats beutifully.
I find that burning pine and other soft wood (construction debris that I call "Rocket Fuel") works best in the batch since there is no coals at the end of the burn.
I burn oak and maple splits and scrap hard wood flooring in the J with no smoke back and no coals at the end of the burn.
No mass for either heater.
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Re: My little J

Postby Bobwieser » Fri Feb 20, 2015 4:41 pm

I forgot a pic of the batch with a glass panel burning strong.
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Re: My little J

Postby mannytheseacow » Fri Feb 20, 2015 6:15 pm

That's awesome that you've even got it in use in your basement. Did you ever do anything with that stove door?
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Re: My little J

Postby Bobwieser » Sat Feb 21, 2015 1:38 pm

Manny, sadly I have not fitted the door yet. Thank You for sending it to me, I do plan to use it.
For now I have the ceramic glass held in place with bricks. The core is set directly on the concrete with 3 bands of plumbers tape (perforated strap) holding the 2 halves together. I know it's not ideal, it's temporary. My basement walls are insulated inside and out with a walk out door and my desk is here so tending the fire is not a big deal. It's nice to have warm kitchen floor and the heat flows up stairs because it's open wide stairs with no door. When I get the temp over 75F I open the door into my garage to heat that too. I put a fan on the floor to blow cold air out of the garage and into the basement, the warm air flows in to replace what's been blown out. I find that's a better way to move warm air around.

Mat I did see a post of yours where you said that when you removed some dense bricks from your feed that it livened up your J. I was hoping that thin wall tiles would work and with the info gained from you I knew what to look for. Since I really never let it cool completely it took a while to remove the tiles. Not that it was so bad but they definitely did cause occasional light smoke back. Removing the tiles helped a lot.

Time to clear more snow.
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Re: My little J

Postby Bobwieser » Wed Feb 25, 2015 12:43 pm

We had an ice storm some years ago, a large tree fell onto my deck and damaged a propane patio heater with other things. I burned that tree.
I took the top off of the heater, removed the burner and set it on my little J.
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It still burns clean and smokes back sometimes since there is no chimney.
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It does get hot and turns red as it should. I'm thinking of putting the old burner in with a gap above the riser to deflect the flames out to the radiant ring.
For now it works as good as before just shorter.
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