Homemade Downdraft Gassifier Wood Buring Stove
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(alarswilson)
Re: Woodgas stoves on 06/20/2006 10:12:33 MDT Print View

Also notable are the contributions of Ray Garlington: http://www.garlington.biz/Ray/WoodGasStove/

and Mark Jurey:
http://www.csun.edu/~mjurey/pennywood.html

I have made both of these stoves (in 5-15 minutes), and they do a remarkably efficient job of burning wood without smoke, without the double wall. I'm not sure the double wall is worth the effort for most occasions.

ALW

Dale Wambaugh
(dwambaugh) - MLife

Locale: Pacific Northwest
Re: Re: Woodgas stoves on 06/21/2006 14:26:13 MDT Print View

Wow-- those are so simple! Is it possible to make one of these where the pot can sit down in the stove a bit and use cross-wise stakes to support the pot?


(alarswilson)
Re: Re: Re: Woodgas stoves on 06/21/2006 14:37:32 MDT Print View

Rig it up however you like. They're surely not as efficient or hot burning as your ingenious double-walled version. The most important aspect of them is the "top-down" burning. If it weren't for this, they are little more than modified hobo stoves, which work by limiting convective heat loss. Having spent many weeks trying to perfect their use under wet conditions, I can say that they do a little better than a simple cooking fire. But any wood stove is no substitute for basic wood craft.

The true champions of efficient wood burning for cooking are the fan-powered cook stoves by Belonio and Reed. Without a fan, there will never be blue-flame, carbon-monoxide free efficiency. See the recent posts by Anderson and Reed on the www.repp.org "Stoves" "discussion list." But these folks are working with impoverished rural populations where fuel shortage is a problem, and smoke is intolerable (as they will be used inside the home like our ranges). Such efficiencies are not needed in the backcountry where smoke is easily dissipated and fuel relatively abundant.

A more ambitious goal might be to develop a wood-burning stove that is acceptable to forestry officials for use in burn-ban areas. As it is, a properly contained wood fire is as safe as an alcohol, esbit, or gas stove (all will wreak havoc if fuel is spilled or kicked) and does burn only a handful of twigs to boil a few cups of water. Is anybody up to addressing this regulatory issue? ALW

Joshua Mitchell
(jdmitch) - F

Locale: Kansas
Nice Job, Ryan F on 06/22/2006 10:55:35 MDT Print View

Nicely done. I had (at one point) tried to make a similar integrated unit stove, but ran into problems as (I believe) mine had a much smaller annulus space than yours did.

Not having enough time to refine my idea, I'm glad to see someone else did.

I suspect that your design could be refined so that a group of boyscouts could make a similar design without the need of power tools (using a church-key can opener, a hold punch, a side-cut can opener maybe a couple other things... some tins snips...) I may need to find some similar-sized cans and try it out.

Miguel, I was just relooking at your pics. Am i wrong, or is the bottom of your 'firecan' (the inner can) solid? did you not put mesh in the bottom? does the ash simply collect in the bottom and you dump it out at the end of the burn?

Miguel Arboleda
(butuki) - MLife

Locale: Kanto Plain, Japan
Re: Nice Job, Ryan F on 06/22/2006 21:46:19 MDT Print View

Hi Joshua, you picked up that little unfinished business in that picture. :P When I took the first indoor photos I hadn't yet found a grating for inside the inner can. Since then I found a lightweight steel drain cover. It's being used in the lit stove picture.

This weekend I will be getting out to the mountains and trying the stove out. I'll bring a backup cartridge stove just in case. SInce it is the middle of the rainy season here, my woodcraft skills will be nicely tested... hope I can find the dry fuel I will need for the stove!

Joshua Mitchell
(jdmitch) - F

Locale: Kansas
Pre-Grate on 06/23/2006 09:27:59 MDT Print View

Ah, good... I was afraid I had missed something in my understanding of gassifying stoves.

No problems then...

Dale Wambaugh
(dwambaugh) - MLife

Locale: Pacific Northwest
Re: Pre-Grate on 06/23/2006 17:09:33 MDT Print View

Yes, I too am grateful for the explaination. :)

David Passey
(davidpassey) - F - M

Locale: New York City
Re: Ryans Woodgas stove on 06/23/2006 18:12:56 MDT Print View

I just built and tested a stove based on Ryan's model. Very impressive--clearly burning the wood gas. Very hot, very efficient, no smoke. The flame was not blue, but was jetting from the holes in the inner can.

I wonder what the burn pattern would be if the holes in the inner were smaller.

On the bottom of the inner can, I just cut big holes will a razor knife for ventilation.

As always, thanks to all for the great ideas and techniques. The forums on this site are a treasure.

Ryan Faulkner
(ryanf) - F

Locale: Mid atlantic, No. Cal
Re: Re: Ryans Woodgas stove on 06/23/2006 19:49:24 MDT Print View

thanks for mentioning the absence of smoke when using the stove, I remember this now that someone said it, I guess I just did not notice while using it, Another great advantage to this design.

Ryan Faulkner
(ryanf) - F

Locale: Mid atlantic, No. Cal
Ryans Woodgas stove stand on 06/27/2006 09:49:37 MDT Print View

I completed the final peice of my stove last night, the pot stand.

I am not sure If it will hold up in high heat I would test it, but it has been raining for the past 4 days and is supossed to continue for the rest of the week

I made it from an aluminum film canister
Image hosting by Photobucket
here is a picture on top of the stove
wood stand 1
It is removable
ryans stand 2
and rolls up to fit in the stove
ryan stand 3
rayns stand 4
ryans stand 5

I also made a change in the fire grate, I made larger holes in the bottom of the can
fire grate

and am using a thin titanium stake to suport the inner can to make more room for air to flow
ti stake

here are a few more pics.
wood stove

wood stove 2
wood sttove 3

the final dimensions are 4"X4.75"

Edited by ryanf on 06/27/2006 09:56:20 MDT.


(alarswilson)
Start with a double-walled mug on 06/27/2006 18:06:33 MDT Print View

If anybody has the time and cash to burn...

Try making a similar stove out of a double walled titanium mug. Try starting with Snow Peak's 21fl.oz (4.4oz) or 15.8fl.oz (3.5 oz) double walled tall stackable cups (http://www.snowpeak.com/gears/tw-stackablecupspage.htm).
---smaller seems impracticable. These are starting weights. Some material will be taken away, and a little added-so they should be close to a finished weight. The price (sans labor) is still less than a Bushbuddy.

1. Remove the handle assembly (if not starting with stackable cup)
2. Cut the majority out of the outer bottom--but leave the lip for strength.
3. Cut the inner bottom out about 1/2-3/4" from the bottom and replace with lightweight SS hardware mesh, or weave your own out of SS wire (or simply pepper the intact bottom with 3/16" holes, ala R. Faulkner's stove).
4. On the outside, Drill 3/8" holes 1/4" from the bottom all the way around w/ 3/8" gap (experiment for best dimensions)
5. On the inside, drill 1/4" holes all the way around with 1/8" gaps (or whatever makes it an even fit--make a template) about 3/4" from the top.
6. For a pot stand, try fashioning some apparatus with titanium wire that will sit over the lip.

From what I've read by those who have designed such stoves, that the size of the holes and their placement matters a lot for the performance of a particular sized stove. I don't know the formulas, but you could search www.repp.org's stove discussion list for assistance, or write to Tom Reed or Paul Anderson.

One could practice with tin cans to get the best setup, then transfer the dimensions to the expensive titanium. There are also many cheaper stainless steel double walled cups that could serve to practice on.

Just an idea--any takers?

Edited by alarswilson on 06/27/2006 18:18:16 MDT.

Joshua Mitchell
(jdmitch) - F

Locale: Kansas
Woodstove from Doublewall Ti on 06/28/2006 08:41:50 MDT Print View

Andrew,

I've considered a similar design myself out of the doublewall stackable cups as they don't have any handles to remove. However I believe that working the holes into the inner wall will be trickey.

I have also considered using the Ti Single Cup (II) (one of each) as I believe it would be easier to work the inner and outer cans seperately and these two should (I haven't actually seen them in real life) stack with plenty of annular space for air movement.

Edited by jdmitch on 06/28/2006 08:42:54 MDT.

Adam Kilpatrick
(oysters) - MLife

Locale: South Australia
wood gassifier using beer cans on 08/04/2006 19:33:32 MDT Print View

has anyone considered or tried making a wood gassifier with a beer can outer and a small steel can inner to save on weight. I am thinking of using a heineken can for the outer. It might be hard to find a lightweight steel can in the right dimensions for the inner though. How hot does can the outer get on the stoves made so far? Would it be hot enough to warp/melt aluminium?


(alarswilson)
Re: wood gassifier using beer cans on 08/04/2006 19:54:41 MDT Print View

The outer can would certainly not get hot enough to melt/burn aluminum--it may char if touching the inner can at the top. Ask Ryan F. how his aluminum pot stand worked--that should let us know if it is a servicable material. ALW

Adam Kilpatrick
(oysters) - MLife

Locale: South Australia
wood gassifier using beer can and mesh inner? on 08/05/2006 01:30:13 MDT Print View

Cheers for the reply Andrew. Ill have to give it a go as soon as I get through this beer.

I am also thinking of using mesh for the top half of the inner to save on weight, which will extend past the top to act as a pot support. But I will see how hot the outer gets first-that might be pushing it too far. Especially as the most available fuel for me is Eucalyptus (In Australia) which burns very hot.

Sam Haraldson
(sharalds) - MLife

Locale: Gallatin Range
Sparks on 08/05/2006 11:06:34 MDT Print View

The minimal research I've done into wood stoves showed that they threw small amounts of spark into the air immediately surrounding the stove. However, seeing as how the models we are particularly discussing are gassifier stoves my information may not be correct.

Frank Deland
(rambler) - M

Locale: On the AT in VA
wood stove designs on 02/24/2007 16:14:59 MST Print View

I tried tin can versions, but found them not easy to light. Then, along came the littlbug (note there is no "e"). I found it easier to light the fire on the ground without the can or chimney. As soon as it gets going put the stove on top. Design your sove without a bottom. If you do not want to do that and have your stove portable while lit, or not scarring the ground, I would suggest designing the stove so the the match can be held underneath the tinder. The flame has a larger area of tinder to ignite. If building a fire on the ground, just dig out a small trench with two fingers, making it easy to get the match underneath. Use the lid of your pot to fan the flames.
http://outdoors.webshots.com/album/556839194qbaYfz
Have you seen the chimneys used to light charcoal for grill cooking. There is a space for tinder (newspaper) to be lit underneath the charcoal. The charcoal sits on a small grate a few inches above the bottom where there are also vent holes. BTW for tinder look for the lowest dead branches on evergreens, like hemlocks. A handful of the smallest twigs on these branches, still attached to the tree, ignite easily.

Edited by rambler on 02/24/2007 16:27:12 MST.

William Golden
(Can-CanBushBuddy) - F
MYO Bush Buddy from Cans on 06/24/2008 18:58:33 MDT Print View

The real Bush Buddy is a highly refined stainless steal stove that weighs 6.5 oz., and burns wood cleanly and efficiently. By analyzing its structure, we can re-create its effectiveness from cans. I've written an article on how to do it for the next issue of Wilderness Way Magazine: http://www.wwmag.net/features.htm . Meanwhile, here are a couple images of it:Can-Can Bush Buddy works and weighs about the same as the real deal.A look within, showing hardware cloth after many hot fires.
Parts: Outer Can: 4" dia x 4.75"; Inner Can: 3.5" dia.x cut height with large bottom hole with four each tabs bent: up and down; Ash Tray: 3" dia x cut height with 4 side-pressure tabs; Half-inch hardware cloth grate inserted into slits for corners; Pot-holder/windscreen: 4" dia x 2" tall, turns over and slides between inner and outer walls for travel, and all fits into billy-can (4.25" dia x cut height to fit) opened with seal-cutter so lid can be re-used. Air-flow spaces all at least a quarter inch. Ashes build up an inch before blocking flow; revive by shaking. Bottom doesn't get too hot for raw-wood surface like picnic table. Easily moved while burning with pliers of multi-tool. Releases almost no sparks even in moderate breeze.

Derek Goffin
(Derekoak)

Locale: North of England
Re: wood gassifier using beer cans on 06/25/2008 04:35:34 MDT Print View

Yes I have done it using a 2 litre aluminium japanese beer can as pot and outer jacket The printing discoloured but the aluminium never got close to melting. see this thread. http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=8025&disable_pagination=1
My pot windshield and stove all nest and weigh a total of 200 gram

William Golden
(Can-CanBushBuddy) - F
Re: MYO Bush Buddy from Cans on 08/04/2008 20:14:08 MDT Print View

I've simplified and lightened my design with a single 4" x 6" can.Four ample draft intake holes (made by bending in double flaps) also serve as a grate.
A grate doesn't have to be continuous. These lower draft hole flaps, bent in, hold up most of the wood, allowing coals and ashes to drop into solid-bottom ash tray, so heated air comes up under wood for a clean burn. Loosely put in tinder, kindling, wood, and light from below.Same size vents above let flames lick pot on their way out. Ample door (2 1/4" wide by 1 3/4" tall) allows feeding of large wood plus more air exchange.
Single piece is strong, light, leaves no trace, no parts to lose or abuse. Burns fast and clean. And of course it needs a small aluminum wind-screen if used in an unprotected place, to prevent embers from getting blown away by a freak wind. Making Tea.

Edited by Can-CanBushBuddy on 08/04/2008 20:55:20 MDT.