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#131114 - 03/23/10 12:42 AM Making my own wood gassifier stove
Pat-trick Offline
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Registered: 06/22/09
Posts: 175
Loc: Portland, OR
I used the Garlington url's, and some others, to make a prototype gassifier stove today, because the Bushbuddy costs $200 with the titanium pot made for it! I found an old piece of galvanized duct work today, and dug a can out of my trash, and I made a double-walled gassifier that is closed at the top of the walls, so that all the heated air has to go into the secondary combustion area. It has a false bottom with tons of holes for primary combustion air, some holes in the sides, and then the major holes 3" above the false bottom for secondary combustion air. My test burn today, using half wet wood, showed that I needed more combustion air. I'll do a burn in the morning, with my watch, and a quart of cool water in a two quart pot. My goal is to boil in a reasonable amount of time, say 10 minutes, and hold the boil for 20 minutes if possible. That way I can make lentils and potatoes stew. Here's a poor picture of it, 'cause the only camera I have is built-in to my monitor. When I get it working, I'll use aluminum flashing to make the outer wall, and keep the 28 oz Progresso Crushed Tomatoes can for the burn chamber. It's 4" diameter, and 4 and 5/8" tall. I cut about a 1/4" off the height.

I found that I really enjoyed tinkering with this project. It was fun, and the time just flew on by. it was even fun squatting in my yard in the rain, watching the thing try to catch on fire. With all the extra holes I gave it, it ought to do much better tomorrow. And hopefully I'll find some dry wood!

Let's see if I can figure out how to add the picture.


Well, I didn't figure out how to do it. It looks like I uploaded the picture, but I don't see it.


Attachments
prototype.jpg


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#131115 - 03/23/10 12:44 AM Re: Making my own wood gassifier stove [Re: Pat-trick]
Pat-trick Offline
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Registered: 06/22/09
Posts: 175
Loc: Portland, OR
Oh, there it is! It shows up after submitting the post. Yay!
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#131196 - 03/24/10 03:23 PM Re: Making my own wood gassifier stove [Re: Pat-trick]
Pat-trick Offline
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Registered: 06/22/09
Posts: 175
Loc: Portland, OR
So far I've gotten up to 150 with the 4" diameter stove. the pot puts the fire out, but when i take the pot off, the fire comes back. it's not getting enough air.
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#131214 - 03/24/10 07:29 PM Re: Making my own wood gassifier stove [Re: Pat-trick]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
SUCCESS!!

I did 4 things differently, and got a rolling boil at 10 min 30 sec.

1: opened the top of the double-wall for air flow through that space, in hopes of improving air flow into the secondary combustion area.
2: made sure no wood was bigger than a pencil, and mixed in quite a bit of smaller. all dry.
3: stopped loading at the low edge of the four secondary venturis. I had loaded up to the top before, an additional 1.5".
4. measured the quart of water, 32 oz. I had been using a bigger pot, and probably more like 2 quarts.

I got the boil without using a lid.

Had some smokiness from 5-8 minutes.
Went into charcoal burning, no flames, at 15 min. Temp 206
temp 206 at 20 min. The fire burned non-stop. (It had gone out several times each testing before today.)

Next time, I'll load predominantly pencil size sticks (1-2" long), with small ones at the top.
I'll also use a lid on the pot. And I'll stick around after 20 min to record temps, etc. I had to go walk before it got dark today.

Tomorrow I will also buy a taller 4" diameter can at the grocery store, for testing with a bigger batch of wood (same diameters though).

Anybody have the perfect wood-burning stove, home-made?
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#131243 - 03/25/10 10:07 AM Re: Making my own wood gassifier stove [Re: Pat-trick]
finallyME Offline
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Registered: 09/24/07
Posts: 2710
Loc: Utah
So, did you consistently feed it, or just fill it once.
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#131263 - 03/25/10 07:23 PM Re: Making my own wood gassifier stove [Re: finallyME]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
I filled it just the one time, shook it to settle all the pieces, dribbled alcohol on the top, and lit it.
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#131349 - 03/27/10 01:04 PM Re: Making my own wood gassifier stove [Re: Pat-trick]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
Back to the drawing board...

I want to bring a quart of water to a boil and keep it there for 30-45 minutes. A one-batch gasifier won't do that.

Today I added a better bottom screen (1/2" hardware cloth as opposed to can top with holes drilled). I also added a 2" collar and put the pot stand on that. That collar concentrated the gases and flames and made a BIG difference. However, I had to add wood continually and had quite a bit of smokiness. So...

I'm thinking to put the secondary air holes at the top of my tomato can (4.5" as opposed to 3"), so that my firebox will be 50% bigger. With the collar on top of that, that might give me better results. Also, I'm going to try bigger wood, placed vertically to improve air flow through the fire. I tried finger sized sticks 3" long, and they burned great (big flames) once they got going. I think it may be possible to add a stick every minute to keep the fire going without smoke, thus I can cook raw beans if I want. Yes, I like to sit around the fire and cook!

Stay tuned.
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#131357 - 03/27/10 05:18 PM Holy Moly [Re: Pat-trick]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
I discovered something today. I removed the bottom of the can, and put in a 1/2" hardware screen. Then I raised the can off the ground, used the collar, and discovered a wood blow torch! A quart of water boiled in 5 minutes flat, and all the wood was consumed in 9 minutes! I'll attach a picture.

My next step is to use a bigger can so I don't have the separate collar. A 7 or 8" tall can, 4" diameter, will do it. I'll use the bottom 2" for the stove stand and adjustable intake openings. That way I can tone it down a bit. No sense in having flame higher than the pot. Then it will need a combination windscreen/secondary air heater, which can be aluminum flashing material. the whole thing ought to be light as the bushbuddy, I would think. I think it will be able to boil at least 2 quarts of water for as long as anyone would want, or short time, too.

I don't remember how to add a picture!

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#131359 - 03/27/10 05:22 PM Re: Holy Moly [Re: Pat-trick]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
OK, use File Manager. Here's the pic.


Attachments
holymoly.jpg


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#131360 - 03/27/10 05:30 PM Re: Holy Moly [Re: Pat-trick]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
and this one shows the screen at the bottom of the can.

I will find a can big enough to act as bottom intake, to replace that wire thing, and also as pot stand, to replace the wire at the top. It will be solid. The bottom 1.5" will have adjustable intake. The screen inside will be heavier duty.


Attachments
HolyMolyBottomScreen.jpg


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#131379 - 03/28/10 09:41 AM Sunday Morning Report [Re: Pat-trick]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
I fashioned an air intake controller - very rough - but it worked, and it made a difference. One quart of water came to a rolling boil at 11:00 flat. It had started to burn too fast, and I restricted the air, and the flame stayed on the bottom of the pot. My apparatus this morning wasn't readily adjustable, but if it had been, I would have been able to make minute adjustments to it to keep the flame just so.

There was a lot of blue at first, and then the flames were bright orange. I need to experiment with the stove screen: spacing, height, openings, etc. But the intake adjustment gizmo will be super.

I fed a couple sticks per minute into the stove and maintained a smoke-free rolling boil for 35 minutes. There was little wind, and I didn't use a pot screen. I discovered that there was an easy rythym of adding sticks, and that this stove likes sticks about finger size. I had to use my pocket knife to score around the bigger sticks and then snap them - just barely! Used to be I could snap small trees with my hands, now I have to use a knife on kindling. I'll for sure need this knife in my gear list. Might even sharpen it some.

My design shows a stove that will be 4" in diameter, with 3 pieces that use tabs and slots to twist and lock into place. The total height from ground to pot bottom is 9 and 1/2". The three sections and the stove screen will dismantle and fit inside the 4" diameter can with a 4 and 5/8" height. The three parts will be made of tin cans. I fit the 1/2" hardware cloth better, and it may do. There's no other wire, no nuts or bolts, duct tape, or gum. The sucker ought to be light. Sorry, no picture today. It's too ugly, being patched and wired together for testing of this and that.

Okay, off toward Jay Mountain for a little test of the legs. Wish I had a cannister so I can take some cold coffee and my pocket Rocket with me. This test wood stove is a big rattly, falling-apart conglomeration of rusted old crap I found laying around in my basement. ha. It would rip my Miwok or fall apart and get lost somewhere. But it's perfect for experiments.

Okay, I'll add a picture I took for a friend last night, maybe two.


Attachments
3.jpg


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#131814 - 04/08/10 09:25 PM Re: Sunday Morning Report [Re: Pat-trick]
larebow Offline
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Registered: 06/19/02
Posts: 36
Hey pat-rick hows the stove coming along?

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#131911 - 04/11/10 07:56 PM Re: Sunday Morning Report [Re: larebow]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
Oh, thanks for asking, I didn't report my last test run. It was after an all-nite rain. I found some "dry" sticks at the base of trees, etc, and got a fire going with great difficulty. I had to use huge amounts of alcohol, and over a 45 minute period I did get a fire going, but it wouldn't handle the air flow being diminshed, as for example, when the pot was on the stove. Since that day, I haven't done anything, because.... well... that wet day put a "damper" on my enthusiasm for a wood stove. I may get back to it shortly.
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#138857 - 09/15/10 11:28 PM Re: Making my own wood gassifier stove [Re: Pat-trick]
NorthTxHillbilly Offline
member

Registered: 09/15/10
Posts: 67
Loc: North Central Texas
Any new news? I'm looking for good advice on a small homemade wood burning camp stove design for an upcoming hiking/camping trip I'm gonna take with my wife and our dog. We're relatively new to hiking but I have lived on the family cattle ranch since I was in elementary school so I'm no stranger to nature.... The wife grew up in the country, too. Usually we take my truck and go to the same places that hundreds of other people camp at but this time we're planning to hike about an eight mile trail and camp at the midway point. Mainly I'm interested in minimizing weight. Any new info on the stove would be greatly appreciated, because I'm going to an area that has plenty of twigs and don't want to have to carry alcohol or cut wood. Your stove sounds perfect for what I'm planning to do.
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#138859 - 09/15/10 11:34 PM Re: Making my own wood gassifier stove [Re: NorthTxHillbilly]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
Originally Posted By NorthTxHillbilly
Any new news?


There are so many tiny details in the wood stove's construction, that are determined by trial and error. The closer I get to a design that works, the closer I get to the Bushbuddy design. So I decided to just buy a Bushbuddy. They have lowered their prices, and you can now get one out of stainless steel, about 5 ounces, for about a hundred bucks. I'm getting one with my next check. I think Bushbuddy has worked out all the details, while I haven't.
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#138862 - 09/16/10 01:02 AM Re: Making my own wood gassifier stove [Re: Pat-trick]
NorthTxHillbilly Offline
member

Registered: 09/15/10
Posts: 67
Loc: North Central Texas
That's a bummer, I'll have to experiment at home a bit, but then again I'm not doing a several day hike with possibly wet wood. If its gonna rain, we're staying home, so with some experimentation and your previous advice, I should be able to make something work. Thanks!
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#138868 - 09/16/10 10:10 AM Re: Making my own wood gassifier stove [Re: NorthTxHillbilly]
finallyME Offline
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Registered: 09/24/07
Posts: 2710
Loc: Utah
You can make a stove that works by just cutting a can up. It won't be as efficient as a bushbuddy, but who cares, you aren't carrying the fuel.
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#138870 - 09/16/10 11:35 AM Re: Making my own wood gassifier stove [Re: NorthTxHillbilly]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
you can find pictures of the bushbuddy on their site, and using a ruler, you can measure the dimensions of their various parts. if you can reproduce what they made, you'll have a stove that works.
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#138880 - 09/16/10 01:31 PM Re: Making my own wood gassifier stove [Re: finallyME]
phat Offline
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Registered: 06/24/07
Posts: 4107
Loc: Alberta, Canada
Originally Posted By finallyME
You can make a stove that works by just cutting a can up. It won't be as efficient as a bushbuddy, but who cares, you aren't carrying the fuel.


And you can leave the cut up can at home, use three rocks you find locally to put your pot on, and not carry any stove either wink

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#138893 - 09/16/10 04:14 PM Re: Making my own wood gassifier stove [Re: phat]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
Originally Posted By phat


And you can leave the cut up can at home, use three rocks you find locally to put your pot on, and not carry any stove either wink



There IS a danger of starting a below ground fire when using an open fire pit on top of the ground. There are layers of dead material that can catch on fire, or simply smolder. We hear stories about smoldering underground fires in the news all the time. I like the idea of the contained wood fire, and especially in something like the Bushbuddy that has double-wall construction. I don't think anyone who uses this forum has ever used one for backpacking, because I've asked for reviews and haven't gotten a single one. In fact, there's been lots of resistance to the idea of using the Bushbuddy or other home-made wood stoves. But, I've heard in other places on the internet that the thing does work. It can be used for boiling water, or some prolonged cooking, or simply for the pleasure of a "campfire". Keeping the fire from contacting the ground makes it safe for the planet. The double-wall construction provides a pre-heated secondary air source for more complete combustion of the wood, and results in pretty much a smoke-free fire. I've gotten that with my own incomplete version of the double-wall Bushbuddy. If anyone decides to use it, they ought to bring a back-up stove, either alcohol, or propane, or one of the many others. Like for when it's solid pouring rain for 3 days. BTW, it's not a wood gassifier technically. It just gives good combustion of wood.
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#138933 - 09/17/10 12:23 PM Re: Making my own wood gassifier stove/"FLAME wars [Re: Pat-trick]
CamperMom Offline
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Registered: 01/04/02
Posts: 1201
Loc: Eastern MA, USA
Hi, Guys-

If we start to debate the merits of 3-rock fire lays VS contained fires and protecting the plane, will we be in danger of starting a "FLAME WAR" here?

LOL!

CamperMom

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#138946 - 09/17/10 06:02 PM Re: Making my own wood gassifier stove [Re: Pat-trick]
phat Offline
Moderator

Registered: 06/24/07
Posts: 4107
Loc: Alberta, Canada
Originally Posted By Pat-trick
Originally Posted By phat


And you can leave the cut up can at home, use three rocks you find locally to put your pot on, and not carry any stove either wink



There IS a danger of starting a below ground fire when using an open fire pit on top of the ground. There are layers of dead material that can catch on fire, or simply smolder.


Sure, if you build your fire on a layer of organic materiel - but this really depends upon where you are. If I'm building my fire on sand, or rock, or clay, or gravel, it's just not the case.

Is it *appropritate* to have an open fire everywhere? heck no.
many places it would definately leave a trace, and many places the act of scavenging for fuel everywhere would adversely affect the place. Similarly flying embers could light fires in very dry places. Places like that are also no place to use a wood stove either.

Quote:

We hear stories about smoldering underground fires in the news all the time. I like the idea of the contained wood fire, and especially in something like the Bushbuddy that has double-wall construction. I don't think anyone who uses this forum has ever used one for backpacking, because I've asked for reviews and haven't gotten a single one. In fact, there's been lots of resistance to the idea of using the Bushbuddy or other home-made wood stoves.


And you've hit the nail on the head - this is a lightweight backpacking forum.I *DO* use a wood fire in *some* places i go where it is appropriate to do so, when I do though, and I'm carrying an alky stove or canister stove for the other times.

Much of the time I am out, I am in sensitive areas in the alpine. in those places I will not use wood, even in a stove.

Coastal hikes with driftwood everywhere? heck, fire on the beach time. no need for a stove there.. high tide and winter storms make it pretty much no trace.

Quote:

But, I've heard in other places on the internet that the thing does work. It can be used for boiling water, or some prolonged cooking, or simply for the pleasure of a "campfire". Keeping the fire from contacting the ground makes it safe for the planet.


It can keep it safe if you want to have a fire on top of a duff layer. Anywhere else, well, the planet has been burning for long before humans - I doubt it will care.

Quote:

The double-wall construction provides a pre-heated secondary air source for more complete combustion of the wood, and results in pretty much a smoke-free fire. I've gotten that with my own incomplete version of the double-wall Bushbuddy. If anyone decides to use it, they ought to bring a back-up stove, either alcohol, or propane, or one of the many others. Like for when it's solid pouring rain for 3 days. BTW, it's not a wood gassifier technically. It just gives good combustion of wood.


I agree completely. The engineer in me loves the things - I love to tinker with them. My only issue with them is the practiality of using them for backpacking in most situations. For me, it's simply a case of:

1) in many situations where I should not have a wood fire, I shouldn't use this either.

2) In situations where I can have a wood fire, I can have one without carrying this.

3) For all other situations, I need a stove.

4) There are concievably some situations where I could use this where I could not have a wood fire. I concede it's possible, and always have. I just haven't encountered such situations, in a lot of backpacking.

5) given the rarity of 4) above, and the fact that for the weight of your a 5 ounce stove I have stove, stand, and 2 to 3
days of fuel for two hot meals a day for one person, I just can't manage myself to make the weight tradeoff - even for the coolness factor.

The most common thing for me to do is have a few places where wood fires are possible, and then adjust my stove fuel load accordingly.




Edited by phat (09/17/10 06:02 PM)
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#138948 - 09/17/10 06:20 PM Re: Making my own wood gassifier stove [Re: phat]
OregonMouse Online   content
member

Registered: 02/03/06
Posts: 6521
Loc: Gateway to Columbia Gorge
I've looked seriously at the possibility of a combination alcohol/wood stove, (the Caldera Cone folks have one) but they are just too heavy. Like phat, if I want a fire and it's legal (not very often where I backpack), I'll just build a small fire in an already existing fire ring.

Out here in the west, in areas close to and above timberline and also in more popular areas, fires are usually banned. Mostly it's because of the scarcity of fuel. The land managers want what little dead wood exists in those areas to decay and replenish the extremely thin alpine soils. A wood stove would be no better than a campfire in this regard, since even small twigs are scarce. We also have seasonal bans--no fires even in the fireplaces in car campgrounds--during times of high fire danger, which usually happen during the "dry season" (July through September, although this year's September is quite wet).

In the East, where you rarely have dry seasons and wood is plentiful if not in too great a supply, it's a different story. I suspect that you'd save enough weight on fuel to offset the extra weight of a wood stove.
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#139045 - 09/20/10 07:14 PM Re: Making my own wood gassifier stove/"FLAME wars [Re: CamperMom]
finallyME Offline
member

Registered: 09/24/07
Posts: 2710
Loc: Utah
Originally Posted By CamperMom
Hi, Guys-

If we start to debate the merits of 3-rock fire lays VS contained fires and protecting the plane, will we be in danger of starting a "FLAME WAR" here?

LOL!

CamperMom


Now that is funny, I don't care who you are. thanks
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#139048 - 09/20/10 07:29 PM Re: Making my own wood gassifier stove [Re: phat]
finallyME Offline
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Registered: 09/24/07
Posts: 2710
Loc: Utah
I agree with phat. And, it took a little while to come to this conclusion. I am an engineer by profession. I think the bushbuddy is freakin' cool. I think the whole concept of a gassifier is awesome. I had to have one. Of course, I couldn't find the money to buy one, and I love to make stuff, so I decided to make my own. I did and it worked great. But then came the thinking on how to make it lighter. Which led to what is the purpose of the stove. To me, the purpose for choosing this stove over others was that you didn't have to carry fuel. And it is better than a can because it burns the fuel more efficiently. Why is it important to burn wood more efficiently when you don't have to carry it? That led to why not just bring a can? A can does the same thing, just less efficient, but cheaper and lighter. And then, why bring a can when a small fire with rocks will do the same thing but be free and weigh nothing? I have never gone anywhere in Utah that didn't allow fires some of the year. If you are concerned about hurting the ground, then bring a piece of sheet metal. Also a trick I learned from earthling is to use two SS bicycle tire spokes to support your cup. I still like wood burning stoves, and think they have their place. But I have a hard time justifying them on a backpacking trip. But, YMMV.
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#139183 - 09/22/10 09:43 PM Re: Making my own wood gassifier stove [Re: finallyME]
JAK Offline
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Registered: 03/19/04
Posts: 2569
I agree with what was just said about efficiency being less important when the wood is free. Efficiency is still important though, because the good stuff might be scarce, and its good to carry enough for the next fire, and efficiency can mean less work saving energy, and efficiency means less smoke, and efficiency oftem means being able to use damp fuel, though not always.

Still, I think a simple can type hobo, properly sized and holed for conditions (somewhat larger for winter) is very competive and often superior to a manufactured stove like the bush buddy. Also, adjustable windscreen type stoves/fires are usually worthwhile improvements over 3rock type stoves, and can be just as compact. In some places you can use more rocks, or a dakota pit, or a Finnish log candle type stove so even a windscreen isn't always a neccessary improvement.

Three things for certain:
1. Global Sustainability often trumps Leave No Trace.
2. Easy to over-generalize with fire and stoves.
3. Messing with fire and stoves never gets old.

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#139208 - 09/23/10 10:58 AM Re: Making my own wood gassifier stove [Re: JAK]
chimpac Offline
member

Registered: 04/06/09
Posts: 148
Loc: alberta,can.
Quote:

We hear stories about smoldering underground fires in the news all the time. I like the idea of the contained wood fire, and especially in something like the Bushbuddy that has double-wall construction. I don't think anyone who uses this forum has ever used one for backpacking, because I've asked for reviews and haven't gotten a single one. In fact, there's been lots of resistance to the idea of using the Bushbuddy or other home-made wood stoves.


And you've hit the nail on the head - this is a lightweight backpacking forum.I *DO* use a wood fire in *some* places i go where it is appropriate to do so, when I do though, and I'm carrying an alky stove or canister stove for the other times.
end quote

I backpack all the time with a woodstove and chimney. What is the weight limit for the chimney/stove to be discussed on the lightweight backpacking forum.

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#139221 - 09/23/10 01:11 PM Re: Making my own wood gassifier stove [Re: chimpac]
finallyME Offline
member

Registered: 09/24/07
Posts: 2710
Loc: Utah
chimpac, I think that a wood stove with a chimney in winter is a completely different animal all together, and my answer changes when talking about this. Also, phat uses a wood stove and chimney in winter. I want to use a wood stove with a chimney, but have yet to make one. I know so little about it, and your pictures are really hard to decipher.

As far as a weight limit, I don't think there is one. If you are going to an area where you would bring a wood stove, then obviously lighter is better. But, if you are going to an area where you can't have a fire because of regulation, then no matter how light a wood stove is, you can't bring it anyways.
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#139268 - 09/24/10 03:30 AM Re: Making my own wood gassifier stove [Re: finallyME]
chimpac Offline
member

Registered: 04/06/09
Posts: 148
Loc: alberta,can.
The stove/chimney I used this summer is all steel and weighs 26 ounces. The weight could be reduced using aluminum and titanium parts. I do not have to worry about how much fuel to carry.
I did some berry picking and filled and sealed the jars on site with a steam canner I made for one jar on my woodstove. When its raining is time to pick over the berrys and cook them inside.
I burn very little wood on a gassifier type stove.I leave no fire scars on the forest floor.

If woodstoves are permitted in a campground or not should not be the issue here just the merits of the function of the stove.

The woodstove phat uses is not good for cooking so he only uses it in winter when he needs the heat.


Edited by chimpac (09/24/10 08:56 AM)

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#139294 - 09/24/10 06:43 PM Re: Making my own wood gassifier stove [Re: chimpac]
OregonMouse Online   content
member

Registered: 02/03/06
Posts: 6521
Loc: Gateway to Columbia Gorge
No matter how good the stove is, it can't be used r where or when either it is illegal, gathering wood fuel for it is illegal or above timberline where no fuel is to be had.

In most of the Cascade range (even this past summer which was cooler and wetter than normal) the use of wood fires--including any kind of wood stove--is banned during the dry season (yes, we do have one!), even in front-country campgrounds with fireplaces, because of the high fire danger.

In addition to the problem of fire scars, many areas near timberline have no dead wood left because so many people have used it up over the years. The Forest and Park Services want what dead wood is left, even twigs, to decay and replenish the extremely thin soils in alpine areas, the main reason wood fires are banned at higher altitudes.

I don't think that someone from eastern North America who has never been in the west and who is used to lots of wood everywhere and frequent rain can visualize conditions out here. You are welcome to come out and find out for yourself!


Edited by OregonMouse (09/24/10 06:44 PM)
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#139317 - 09/25/10 01:32 AM Re: Making my own wood gassifier stove [Re: OregonMouse]
chimpac Offline
member

Registered: 04/06/09
Posts: 148
Loc: alberta,can.
I am really sorry you can't burn wood where you want to go, so you have to make the best of it and use what you can for cooking.
This thread is really about making a gassifier stove, are you saying forget it, you will never use it because there is no place to burn it?
It is good to be informed about where a woodstove on a chimney in a tent is legal and I would be interested in a thread devoted to the subject.

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#139323 - 09/25/10 05:26 AM Re: Making my own wood gassifier stove [Re: chimpac]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
Originally Posted By chimpac
I am really sorry you can't burn wood where you want to go, so you have to make the best of it and use what you can for cooking.
This thread is really about making a gassifier stove, are you saying forget it, you will never use it because there is no place to burn it?
It is good to be informed about where a woodstove on a chimney in a tent is legal and I would be interested in a thread devoted to the subject.


Let me squeeze a comment in here. I don't believe the Bushbuddy and other double-walled stoves are gassifiers. The double wall design simply adds a secondary air inlet of warmed-up air, for more efficient burning.

I was playing with my variation of this type stove yesterday, and the wood was wet, but i used birch bark like paper, twigs, and then big chunks of wood. After 5 minutes of smoking, the fire got going and lasted about ten minutes. Almost got 2 cups of water boiling. I think the trick is in selecting wood that will get hot and burn long. I have no idea what kind of wood I was burning yesterday, but it wasn't pine. Another trick is to load BIG chunks in the thing, sort of like we do with a home wood stove. After the first 5 minutes, when the thing was trying to get going, there was NO smoke at all. Next time I'll use bigger diameter chunks on top, to see if I can get a boil out of one load of wood. The diameter I was using yesterday was about an inch, an inch and a quarter, for the big stuff. I load the stove with peeled and crumpled birch bark, and then make a hatchwork pile with teensy twigs on top of the birch, and bigger twigs, up to pencil diameter, in the criss-cross pattern half way up the can, then the chunks on top.

With my stove design, there are separate inlets for combustion air for the fire itself, and for the secondary combustion area at the top. Also, if the bottom fills up with combustion debris, I can remove the cook pot, and using a couple longish twigs, pick the stove up while it's burning and move it over, leaving the ashes behind. The bottom is open. Of course it has to be used on a flat rock. I can also add birch bark below the fire to help it out a little, by stuffing it through the primary inlets with a little twig. That's helpful when adding more fuel to keep a fire going. I removed the primary and secondary air adjustment mechanisms for now, because they were getting hard to operate due to the cans being outside all this time and getting a little rusty. woops. I've got a dozen prototypes outside laying around.

For me, here in the east, the wood stove is fun, mystical, my connection to my neanderthal brothers (not you guys), and it's something I do for me. My wanting to mess with it outweighs my concerns for saving 2 ounces. Also, I am happy to not use fossil fuel whenever I can. I know it's different out west, thanks to all the emails describing the situation there. Bummer for you westerners! The thrill of camping for me has always been defined by "the campfire" and things I could put in one. Somemores, marshmallows, hot dogs, my camping buddy... not to mention all the lies and tall tales told boldly. Just kidding about the buddy. Fire is sort of magical out in the woods.

It's interesting that just this week Hillary Clinton was talking about clean-burning stoves for undeveloped countries. The gassifier is just such a stove. It was designed for that kind of use. It's really complicated, clean-burning, and it does convert wood into gases that are then burned. I think it's also a downdraft type of combustion. I don't know of a true downdraft gassifier that is functional for a backpacker. Does anyone know of one? Do we have an expert who knows about this stuff?

Well, if it's a gassifier, or just an efficient burner, I like the idea of a smoke-free fire. I haven't really learned all the nuances of how to use mine yet, but it's a cool way to burn some time, pun intended. Better than sitting in front of the monitor (the new TV, complete with advertisements on every freakin webpage). I know that the Bushbuddy instructions say to "practice, practice, practice!" To use it well probably involves learning about the different kinds of trees, and the burning characteristics of each kind. Every kind of tree burns differently from all the others, and moisture affects them differently, as well. Also, being green or cured makes a difference. I may NEVER learn how to use this thing completely!

On a different note, I was awarded disability (yay!), but the gov't decided to change the date of onset a couple years, thereby screwing me out of 36 grand. I said screw that and am presenting more evidence. If I have to, I'll appeal to the federal courts. I was hoping to get my backpay this month. It's been six years now since I've worked gainfully.
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#139324 - 09/25/10 05:30 AM Re: Making my own wood gassifier stove [Re: Pat-trick]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
The bottom is open, but there is a wire mesh a half inch above the open bottom, to hold charcoal and burning wood. Only the ashes drop through the wire screen.
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#139325 - 09/25/10 05:35 AM Re: Making my own wood gassifier stove [Re: Pat-trick]
Pat-trick Offline
member

Registered: 06/22/09
Posts: 175
Loc: Portland, OR
I'll try to get some pictures today.
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#139341 - 09/25/10 08:50 PM Re: Making my own wood gassifier stove [Re: chimpac]
Trailrunner Offline
member

Registered: 01/05/02
Posts: 1835
Loc: Los Angeles
Originally Posted By chimpac
The stove/chimney I used this summer is all steel and weighs 26 ounces.


Just curious, why would you carry a chimney in the summer? I can see just a wood stove, but a chimney adds a lot of weight. Is it really cold where you camp in the summer?
_________________________
If you only travel on sunny days you will never reach your destination.*

* May not apply at certain latitudes in Canada and elsewhere.

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#139344 - 09/26/10 12:45 AM Re: Making my own wood gassifier stove [Re: Trailrunner]
chimpac Offline
member

Registered: 04/06/09
Posts: 148
Loc: alberta,can.
It all depends on the weather.
How many days is it comfortable to have breakfast out side on the patio. Canada is cooler than California and this summer we have had alot of stormy weather when nobody is out on the patio. When you carry a chimney you have the option of being inside out of the wind, rain and smoke. I do not need a different rig for the coldest winter weather.

Without a chimney a camp shelter is only a fair weather outfit. You can tell that by how many tenters there are after labor day or before June here in Canada, their equipment is designed only for fair weather. We have days in summer when the temperature does not get above 10 C. Its no fun cooking and eating in a cold wind around a little gas stove and in the rain its impossible.
How much is a "lot of weight"?


Edited by chimpac (09/26/10 09:48 AM)

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#139348 - 09/26/10 12:23 PM Re: Making my own wood gassifier stove [Re: chimpac]
Trailrunner Offline
member

Registered: 01/05/02
Posts: 1835
Loc: Los Angeles
Originally Posted By chimpac
How much is a "lot of weight"?


26 ounces. But it is you who carries it, not me. What works for you is all that really matters. But it is possible to be completely warm and comfortable in the winter without a chimney. That is one luxury I can do without.
_________________________
If you only travel on sunny days you will never reach your destination.*

* May not apply at certain latitudes in Canada and elsewhere.

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#139349 - 09/26/10 01:21 PM Re: Making my own wood gassifier stove [Re: Trailrunner]
chimpac Offline
member

Registered: 04/06/09
Posts: 148
Loc: alberta,can.
Originally Posted By Trailrunner
Originally Posted By chimpac
How much is a "lot of weight"?


26 ounces. But it is you who carries it, not me. What works for you is all that really matters. But it is possible to be completely warm and comfortable in the winter without a chimney. That is one luxury I can do without.


Chimney with top carrier, bottom base, coupler weighs 16 ounces out of the total 26. I can make an effort to take that weight down useing aluminum to maybe 10 ounces if the 6 ounces extra is going to make me to tired.

I would like to compare that with what you carry for just cooking no heat. For cooking outside in whatever weather.

What does your stove, windscreen and fuel weigh for a weeks trip?

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#139353 - 09/26/10 03:41 PM Re: Making my own wood gassifier stove [Re: chimpac]
Trailrunner Offline
member

Registered: 01/05/02
Posts: 1835
Loc: Los Angeles
Originally Posted By chimpac
I would like to compare that with what you carry for just cooking no heat. For cooking outside in whatever weather.

What does your stove, windscreen and fuel weigh for a weeks trip?


Sorry, I'm not competing against you. Your needs are not mine. Carry whatever you wish. I don't cook outside in bad weather and I don't need the extra weight of a chimney to cook inside. Your system would never work for me.
_________________________
If you only travel on sunny days you will never reach your destination.*

* May not apply at certain latitudes in Canada and elsewhere.

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#139356 - 09/26/10 07:11 PM Re: Making my own wood gassifier stove [Re: Trailrunner]
CamperMom Offline
member

Registered: 01/04/02
Posts: 1201
Loc: Eastern MA, USA
Jumping in---

None of use should be competing when anyone is seeking information. Shouldn't this be about "HYOH?" Summer was brutally hot in a lot of the eastern USA, especially North Carolina through Virginia, where I was over the summer. A week's worth of fuel for me in the summer might be 3.5 to 6 Esbit tablets, assuming I am backpacking and trying to crank out miles. I have lots of toys, but keep going back to a Vienna sausage can for a pot. My cookset: pot, lid, spoon, insulated Ziplock Bowl, titanium wing stove is probably 3 ounces. That may be fine for me with easy resupplies of precooked-prepackaged meals that only neeed water to reconstitute. If I had to buy food in towns and cook it, things would have to be different. If the weather were cold/wet, my plan might have to change. As it is, in summer, I might totally skip coffee for caffeinated gum, coffee beans (maybe in chocolate), or a cold mountain latte made with instant coffee and dry milk. We all have to do what works for us.

CamperMom

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#139366 - 09/26/10 11:26 PM Re: Making my own wood gassifier stove [Re: CamperMom]
oldranger Offline
member

Registered: 02/23/07
Posts: 1735
Loc: California (southern)
Another consideration is fire safety. In the American Southwest (including California) fire restrictions are frequently in effect. Often the last type of stove allowed would be a canister system. I have seen conditions where I would not even light one of those, going instead for cold meals. At that point, in my opinion, it is best to not be in the woods at all.

On the first days of autumn, it has finally warmed up here in SoCal, and Santa Ana winds are in the forecast.

HYOH and peace.

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#139369 - 09/27/10 04:13 AM Re: Making my own wood gassifier stove [Re: Pat-trick]
chimpac Offline
member

Registered: 04/06/09
Posts: 148
Loc: alberta,can.
Here is what I have learned about a makng a stove burn as a gassifier.
It has to have two zones,
one zone where the wood is cooked to slowly release the gas.
The other a very hot zone where the gas (smoke) burns.
This can be done if the wood is stacked vertical and burned from the top down. The top supplied with good draft directed at the flame. The bottom deprived of oxygen, only getting enough to cook the gas out of the wood.
The smoke from the bottom will put the fire out on the top if the fire on the top is not hot enough. Small stuff has to be added until it burns hot enough. You should always see flames on the top. My stove is closed on top, draft comes in at flame level. The smoke exits out the back. There is a draft opening at the bottom that is closed or almost closed. I have not experimented much with a stove with an open top.


Edited by chimpac (09/27/10 04:28 AM)

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#139370 - 09/27/10 06:29 AM Re: Making my own wood gassifier stove [Re: chimpac]
JAK Offline
member

Registered: 03/19/04
Posts: 2569
I also like the idea of a close topped hobo stove. I've seen some old hobo designs like that. Not as sofisticated as yours, just hole near bottom and hole near top, but with the can upside down as opposed to what is usually done. Upside is you get a hotter combustion temperature. Downside is you can have some trouble getting the heat to your pot. Also, you still need some sort of insulation from the ground, especially wet ground or snow, and some sort of a grate helps also, but I question the need for a grate really, if gasification or partial gasification is what you are after anyhow.

The other thing I wonder about is the best design if you want to use the stove both for cooking and for throwing some heat. The open top type isn't bad if you are sitting over it, but I think the closed top and open side is probably better.

With a simple coffee can type stove you could always use it right side up or upside down I suppose. The best base in both cases might be another can. Perhaps a tuna can. Or perhaps it could be your can for holding tinder and burning char. Normally you would make char with the can over the fire, but if it was under, that might work and provide insulation and volatile gases at the same time, through a pinhole. Still some more insulation under that setup would still be helpful. It starts to get overcomplicated again.

This is beginning to appeal to me again...
http://www.youtube.com/watch?v=wEHSJftQ9Vg&feature=related

OK, so carrying a chainsaw is sketchy. Even with a handsaw, getting 6" logs isn't practical. But what about driving one green stick into the ground like a stake, and then bundling 6 sticks around it with some snare wire or some sort of band clamp. Or perhaps a thin sheet around them to serve also as a wind screen. Maybe 3 stakes would be better, or the wind screen metal would serve as the legs or reinforce the legs. Anyhow, the ide would be to tightly bundle roughly 7 2" diameter sticks together, with the center stick being only 2" tall, and the others at least 6" taller, except one maybe where the chimney hole goes out. Some sort of tuna can for a stove top.

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#139706 - 10/01/10 11:58 AM Re: Making my own wood gassifier stove [Re: chimpac]
chimpac Offline
member

Registered: 04/06/09
Posts: 148
Loc: alberta,can.
I have discovered that I can get a gasifier burn with a horizontal firebox if there is a baffle or part of a baffle in the stove to make the smoke go to the front of the stove to get out.
New wood or wet wood is put to the back of the stove, the hot coals and burning wood is raked to the front next to the front draft.

I prefer a vertical stove because.
A horizontal firebox delivers most radiant heat more up and down.
A vertical firebox delivers more radiant heat sideways.

A horizontal stove laying down in the corner of the tent does not deliver as much radiant heat to the bodies in the tent as a vertical stove standing in the middle of the tent.


Edited by chimpac (10/01/10 12:07 PM)

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#139759 - 10/02/10 02:20 PM Re: Making my own wood gassifier stove [Re: chimpac]
JAK Offline
member

Registered: 03/19/04
Posts: 2569
You got me to thinking about how to make a stove more directional, for a solo hiker/camper. It is true what you say, but only if the outside surfaces are the same temperature. The top is usually even hotter, which reinforces your point.

So what if the stove was better insulated all around, even on top when you don't have a pot on it, and then you opened the door to allow heat to radiate out directly in that drection only. With more insulation on the other sides you would still maintain a high combustion temperature. If the stovepipe was small enough in diameter and not to tall in height you would not get too much airflow, and your stovepipe would be lighter in weight. You would probably still want a baffle.

So how much heat can you radiate from a 4"x4" opening?

Heat Tranfer Rate, q = 5.6703 10-8 (W/m2K4) x A x (Ts^4 - Ta^4)
(Area, A in m2; Temperature, T in degK)

Area, A = 4"x4" = ~ 0.01 m^2
Ta = Ambient Temperature of say 300K
(80F surface temperature of person sitting in front)

Ts = Stove Temperature of 260F to 800F depending.
400K = 260F: 10 watts = 9 kcal/hr
500K = 440F: 31 watts = 27 kcal/hr
600K = 620F: 69 watts = 59 kcal/hr
700K = 800F: 132 watts = 113 kcal/hr
800K = 980F: 228 watts = 196 kcal/hr

For every ounce of wood burned (roughly 1"x1"x4") at 20% moisture you will get about 400 BTU = ~ 100 kcal, so if you can achieve 10% efficiency in terms of direct radiant heat, if that is your aim, it would require 10 ounces of wood per hour to transfer 100 kcal/hr, or 30 ounces per hour to transfer 300 kcal/hr. Of course there will be other useful heat by thermal radiation and convection to the space and other surfaces, such as you sleeping bag, hanging clothes, cook pots, fuel supply, that sort of thing. It shouldn't take much heat for a small space, but with a wood stove you can't really run it all night like a candle or oil lamp, so its nice to be a little larger to get a really good drying out heat in a short span of time. Still, doesn't take much of a stove to do that for a small space. It would be interesting to go even smaller, also with a smaller diameter stovepipe. Say a 4"x4"x8" firebox or even smaller. Perhaps a vertical batch load, so maybe 4"x4"x4" of fuel, and 4"x4"x4" of space above that, but designed and packed in such a way to burn down uniformly and slowly.

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#139761 - 10/02/10 02:37 PM Re: Making my own wood gassifier stove [Re: JAK]
JAK Offline
member

Registered: 03/19/04
Posts: 2569
p.s. But if like stay horizontal, with the 4"x4"x4" jammed to the back of the stove, with the 4"x4"x4" combustion space in front of that, with a baffle above so that air flow in through the open door and combustion gasses pass forward under the baffle and then up and over the baffle and back across the top of the baffle and under your cooking surface when not covered, and then up the stovepipe. In such a conventional configuration, even though it is horizontal, it should radiate most heat out through the door while it is open, because you can see the wall of flame as it burns through the batch of wood. Also, as ash builds up it can fall and be scraped away.

So maybe horizontal is better.

p.p.s I like your design with the stove simply cantilevered off the stovepipe. The stove should be light enough for this, even when loaded and with a pot on top. Not sure of best diameter and height for a stovepipe, when minimizing weight. I like the idea of switching to aluminum tubing after a certain distance from the combustion zone. Perhaps the entire stovepipe could be a single aluminum tube, doubling as the tentpole, and hiking staff. As long as the baffling and insulating was done right, and the stove was loaded and operated right, I can't see that being a problem. You could then go with a diameter that is just comfortable as a hiking pole without being too big, like 1-1/4" maybe, or 1" if you could make the stove small enough.

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