BOOH VII

Rocket Mass Heaters, Rocket Ovens, Cold boxes, Solar collectors, etc..
Talk about your projects

Moderator: matt walker

Re: BOOH VII

Postby Nutcase » Sun Apr 28, 2013 12:20 pm

Here's a link to the offer for firewood I'm considering:

http://portland.craigslist.org/mlt/grd/3753821247.html

I talked to someone at the place offering it, he said it weighs about 8000 #/cord, which works out to over 60 pcf. Pretty close to the density of water. Not much cordwood actually sinks, does it? That got me to thinking, why not build a thermal mass out of this stuff? Well, I suppose some of it might have an aroma at bench temperature...but still, this is an idea worth considering. Again, it's something that can be undone or redone if it doesn't work out, and it could be implemented without extensive remodeling.
Mark
(aka Nutcase)
Nutcase
 
Posts: 145
Joined: Fri Dec 21, 2012 10:35 pm
Location: NW Oregon

Re: BOOH VII

Postby matt walker » Sun Apr 28, 2013 5:10 pm

Wow, that seems to be a great deal. That stuff will go a long ways being so dense.
User avatar
matt walker
Site Admin
 
Posts: 1803
Joined: Tue Jan 03, 2012 5:50 pm
Location: North Olympic Peninsula

Re: BOOH VII

Postby Nutcase » Sun Apr 28, 2013 11:18 pm

Last week I think I got a better idea about what is meant by "working a mizzou slurry into the blanket." In any case, so far it looks like I've found a way to handle it that is reasonably simple and effective. Here is what I have so far:

Image

This is the fourth of these letterbox pieces that I've made and the first I've gotten off the form without breaking it. It's still damp and unfired, but okay for gentle handling off of this form:

Image

The polyethylene sheet is taped onto the bottom of the form, so anything on the sheet can be rolled up and wrapped around between layers. I used a strip of duct tape to mark an appropriate position for the blanket and applied the mizzou. The procedure for that was straightforward:

1) Scoop up a cup or two of mizzou from the bag and pour it into a large mixing bowl.

2) Add water, mixing by hand, until soupy. Don't bother with gloves if your skin isn't delicate. It's just mud, more or less.

3) Scoop up a handful and smear it on the blanket. The blanket soaks up excess liquid, carrying fine particles and whatever is soluble. Further smearing turns into rubbing, which dislodges the larger solid bits, which can be brushed off to the side. Second scoops from the same mix have a higher proportion of finer particles, so this can be used fill divots and low spots. After the second scoop, it's time to add more mizzou and water as necessary. Keep at it until the coverage is as thick and uniform as seems reasonable.

Then I rolled the coated blanket up snugly. I think this stuff is 3 mil, and it was adequate for the load, but thicker would be better. The mizzou doesn't adhere to it.

After 22 hrs, it had set up enough to unwrap. I used a cast saw to trim some excess on one side and square up the edges a bit. I expect it to become stiffer and less fragile as it air dries. Tomorrow I will bake it.
Mark
(aka Nutcase)
Nutcase
 
Posts: 145
Joined: Fri Dec 21, 2012 10:35 pm
Location: NW Oregon

Re: BOOH VII

Postby matt walker » Mon Apr 29, 2013 12:59 am

Wow NC, awesome technique. So you are rolling the wetted composite over the mold after wetting out? Neat.

If part of the difficulty in removing them from the mold is adhesion, you might try coating the mold in packaging tape, then using some veggie oil as mold release.
User avatar
matt walker
Site Admin
 
Posts: 1803
Joined: Tue Jan 03, 2012 5:50 pm
Location: North Olympic Peninsula

Re: BOOH VII

Postby Nutcase » Mon Apr 29, 2013 5:03 am

matt walker wrote:Wow NC, awesome technique. So you are rolling the wetted composite over the mold after wetting out? Neat.


Thanks! It's more accurate to say that I am rolling the mold over the wetted composite, though.

In previous attempts at this, the issues have been structural/procedural. Adhesion to the PE sheet is totally not an issue. Not obvious from the picture, but there was one entire wrap of the sheet around the mold before I wrapped the mizzou and blanket, then a few more wraps.

For the first one, I tried to mix and apply a large batch all at once. Too much big aggregate for the thickness, plus working out the wrapping method on the fly, it was "almost good." The second one, the one I sifted the material for, got cracked in early handling, but it's holding up fine as the burn channel in my current system. It's just too thin for handling when green, plus the sifting took out the fibers, which I clearly see contribute a lot to green strength. The third was a failure in the handling during layup. Trying something different, I didn't get the blanket with mizzou onto the form with the mizzou in place. It was in the process of trying to salvage something from the subsequent slumped mess that I got onto my current method for handling the material. Anyway, this way works, it's dead simple once you have the form set up, and the way to set up the form is straightforward, so not much point in going into all the wrong turns in further detail.

There are some rough edges on the process still, literally. The mizzou squishes out a bit as it is wrapped, and anyway it's a little bit tricky getting the thickness uniform and not allowing the coarser aggregate to pile up. The cast saw is good for cutting plaster, and it is working okay on the mizzou while it's green, but the blade I have is just a metal blade, not adequate by a long shot for actually cutting this material when it's hardened. Maybe I will eventually need an angle grinder.

Eventually I will attach some pictures to this process description. This time my wife wasn't around, and I had my hands full...
Mark
(aka Nutcase)
Nutcase
 
Posts: 145
Joined: Fri Dec 21, 2012 10:35 pm
Location: NW Oregon

Re: BOOH VII

Postby matt walker » Mon Apr 29, 2013 3:09 pm

Got it, I didn't realize you had the mold covered with the film as well. I've found refractory cuts like butter with a diamond blade on an angle grinder. There are diamond masonry blades available for circular saws as well if that is an option for you.
User avatar
matt walker
Site Admin
 
Posts: 1803
Joined: Tue Jan 03, 2012 5:50 pm
Location: North Olympic Peninsula

Re: BOOH VII

Postby Nutcase » Mon Apr 29, 2013 4:25 pm

Thanks for that point of guidance. I have circular saws, but the angle grinder option would probably be best for this stuff, due to the thin and unflat conformation. Just FYI, the cast saw has an oscillating action with a circular blade, so it cuts rigid stuff but doesn't cut skin. Hmmm, it might even work with a small diamond blade, assuming the anchoring of the diamonds isn't too asymmetric. Not a particularly demanding usage. On the other hand, Harbor Freight has cheap angle grinders , and I will eventually want one for working on water heater cores and stuff like that anyway.
Mark
(aka Nutcase)
Nutcase
 
Posts: 145
Joined: Fri Dec 21, 2012 10:35 pm
Location: NW Oregon

Re: BOOH VII

Postby mannytheseacow » Fri Feb 21, 2014 6:43 pm

Back when I joined this forum there were two things that really made me join. One was the cast core idea and the other was this Nutcase guy who was doing all this experimental stuff and posting pictures and stuff. Whatever happened to that cat? I miss Nutcase.
"Knowledge is power. Arm yourself."
User avatar
mannytheseacow
 
Posts: 940
Joined: Sun Feb 24, 2013 12:40 am

Re: BOOH VII

Postby matt walker » Fri Feb 21, 2014 6:45 pm

I do too, he was doing some super cool stuff that still is ahead of the curve, in my opinion. I hope he's out there with some super rocket heater blowing minds in his neighborhood. I wish he'd come back though.
User avatar
matt walker
Site Admin
 
Posts: 1803
Joined: Tue Jan 03, 2012 5:50 pm
Location: North Olympic Peninsula

Re: BOOH VII

Postby Nutcase » Mon Apr 18, 2016 3:31 pm

Greetings. It has been a while, close to three years, since I visited this site.Thanks for the kind words, Matt and Manny...T.? Just got that. Anyway, long story short, various things happened, now I'm living out in the country NW of Portland and I'm looking forward to making this forum (and rocket stoves) part of my life again.

My work with rocket stoves pretty much stalled out at the time I stopped posting. For the '13-"14 heating season, I did kludge together something like I had used the previous year, built around the burn channel piece pictured above. The following spring we left our home in the suburbs and moved to where we are now, a place where neighbors don't complain about your roosters. Up to now, we've been managing with a badly installed but functional conventional wood stove (Fisher "Papa Bear"). I had thought to replace that stove this year as part of a drastic remodel. Then, about a week ago, we stumbled onto an opportunity to move to a bigger property (7.3 vs. 1 acre) with a better house only 1.4 miles up the road. With what amounts to an unheated, unfinished 1200 sq. ft. above-grade basement as part of the deal, I will have plenty of both motive and opportunity to get back to rockets.

I have been doing some things with cattle panels and 2x4s that I will post about elsewhere on this forum as time allows. Have a lot of catching up to do, plus moving.
Mark
(aka Nutcase)
Nutcase
 
Posts: 145
Joined: Fri Dec 21, 2012 10:35 pm
Location: NW Oregon

PreviousNext

Return to Heating and Cooling

Who is online

Users browsing this forum: No registered users and 1 guest

cron