Donut shaped center draft alcohol stove
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Colin Krusor
(ckrusor)

Locale: Northwest US
Donut shaped center draft alcohol stove on 01/22/2013 23:20:36 MST Print View

The outer part of this stove is made from the bottoms of two standard size soda cans and the inner is a segment of an old aerosol-toothpaste can (?). A wine bottle was used to flare the inner aluminum tube over the outside lip of the outer parts, to mechanically hold the assembly together and neatly finish the edge. That junction is also sealed on the inside by a small amount of high-temperature silicone. There are twelve pretty large holes in the inner part (about 1/16") and one hole in the outer part with a small allen screw for filling with fuel. A small mound of high-temperature silicone on the inside has female threads and seals around the screw when it's in place so fuel vapor only escapes from the jets. Fuel is added from a syringe that I carry in my first aid kit anyway.

I decided to try the donut shape because I thought it might be possible to construct a bowl-shaped windscreen that has a hole in the bottom and seals around the stove. I thought this might be a good way to prevent gusts from introducing cold air into the space around the pot (inside the windscreen). With a bowl-shaped windscreen that is sealed at the bottom around a donut-shaped stove, all of the gas around the pot is hot stove exhaust, and a chimney effect draws cold outside air through the flame. This idea might not be worth pursuing, but this was my reason for considering a stove of this shape.

In three boil tests this stove brought to a boil two cups of about 57F tap water in an average of 6:33 min. and burned for an average of 7:51 min. using 15 ml of a 50/50 blend of methanol and ethanol. In the photos below I added a pinch of boric acid to the fuel to make it easier to see (makes it greenish). The stove is primed by burning a small amount of fuel on a small disc of heat-resistant fabric (a "CarbonX" PAN knit). The stand is made from 0.01" thick 15-3-3-3 titanium. The stove, stand, and priming pad together weigh 15 grams (0.5 oz).

stove

stove1

stand

stand1

stand2

pad

screw

flame

flame1

flame2

This is a photo of the stove from underneath:

flamebottom

scale

Franco Darioli
(Franco) - M

Locale: Melbourne
Donut shaped center draft alcohol stove on 01/23/2013 01:56:36 MST Print View

That is a great looking stove !
I like the ti stand/sleeve.

John Donewar
(Newton) - MLife

Locale: Southeastern Louisiana
Re: Donut shaped center draft alcohol stove on 01/23/2013 03:26:24 MST Print View

Colin,

Nicely done!

;-)

Impressive pictures and workmanship. :-)

When do we get to see the windscreen?

Party On,

Newton

Dan Yeruski
(zelph) - MLife

Locale: www.bplite.com
Pot Support on 01/23/2013 06:38:44 MST Print View

Nice "dual flame" I like it. How tall is your pot support?

Louis Jewett
(lfjewett)
Re: Pot Support on 01/23/2013 08:51:59 MST Print View

Great project!!! The one worry I would have is the High Temp silicone failing and the internal fuel assembly leaking. If it proves sound could this stoves flame be controlled by a air restriction plate on the bottom? It would give you a way to adjust from simmer to full blast with a BBQ style air intake?

Yohei Aoyagi
(zzz_bear) - MLife

Locale: Tokyo
Re: Donut shaped center draft alcohol stove on 01/23/2013 12:27:33 MST Print View

Nice job.
Shara Project make a few donut styled hole alcohol stoves in Japan.

http://www.shara-project.com/field/

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Donut shaped center draft alcohol stove on 01/23/2013 13:33:40 MST Print View

Elegant.

Cheers

Nathan Hays
(oroambulant)

Locale: San Francisco
Donut stove on 01/23/2013 20:06:19 MST Print View

Now I know what I'll be doing tonight. Really, really nice.

Dan Yeruski
(zelph) - MLife

Locale: www.bplite.com
Center Draft on 01/23/2013 22:19:31 MST Print View

Thsi stove I designed years ago and Tony Beasley of Australia machined it for me out a solid piece of aluminum.

The photobucket video was made with a camera that had a 20 second video application. Seems ancient.

Colin Krusor
(ckrusor)

Locale: Northwest US
Stove height on 01/24/2013 09:39:47 MST Print View

Thanks for the responses. I'll post an update once I get a chance to finish the windscreen that I had in mind for this stove.

Dan, the pot is elevated above the ground 3.5", and it's 1.25" above the stove. The requirement for the stove to be elevated about 1" on its own little stand is one of the shortcomings of this design, I think. It pushes the pot up and requires a taller windscreen.

Louis, so far the silicone seems to be holding up. I added it as a precaution, but I'm not sure that it was actually necessary. The aluminum surfaces at the junction of the inner and outer parts of the stove are smooth, and they are crimped together pretty tightly. Besides that, the silicone at the bottom, that protects against leakage of liquid fuel, never gets hotter than the temperature of boiling alcohol, which is either 150F or 175F depending on the type (methanol or ethanol), and lower than that in the mountains. The silicone I used should tolerate temperatures approaching 800F (and higher for brief periods). That's high enough to anneal the aluminum of the stove, and much higher than normal operating temperatures, even right around the jets.

Alan Bradley
(ahbradley)
Re: Re: Donut shaped center draft alcohol stove on 01/27/2013 13:42:26 MST Print View

Couldn't such a design have low CO emission?

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Donut shaped center draft alcohol stove on 01/27/2013 14:22:22 MST Print View

> Couldn't such a design have low CO emission?
Not guaranteed, but with the increased availability of air it is possible.

Cheers

Ktaadn .
(ktaadn)

Locale: New England
Sheet of titanium .01 thick on 03/15/2013 10:43:44 MDT Print View

Beautiful stove!

Where would you recommend me finding a small sheet of titanium in the same thickness of your pot stand?

Thank you

Angus A.
(mangus7175) - F

Locale: http://theshadedtrail.blogspot.com
Re: Donut shaped center draft alcohol stove on 03/15/2013 11:00:13 MDT Print View

Talk about stove pr0n! That is a thing of beauty...very clean design.

Jordo _99
(jordo_99) - MLife

Locale: Nebraska
Ti source on 03/15/2013 11:27:09 MDT Print View

@Kasey, searching Titanium foil or Titanium sheet on ebay should come up with a number of thicknesses and sizes that would work.

...likely you would want something around .005" or a little thicker...I know that's the thickness most windscreens are made out of.

I've been looking lately and found numerous sales that would give enough Ti for around $20 or less...likely being able to make a few of them.

Brandon =Þ
(Beeen) - MLife

Locale: California
Re: Donut shaped center draft alcohol stove on 03/15/2013 12:15:47 MDT Print View



I made this my desktop background.

Ktaadn .
(ktaadn)

Locale: New England
Re: Ti source on 03/15/2013 12:20:08 MDT Print View

Thank you JP

Nick Larsen
(stingray4540) - F

Locale: South Bay
Re: Donut shaped center draft alcohol stove on 03/15/2013 13:09:21 MDT Print View

That is a pretty awesome little stove!!!
I would be interested to see you play with the hole sizes though. I wonder what a larger amount of smaller, needle holes would do to the boil times and file usage...

Colin Krusor
(ckrusor)

Locale: Northwest US
Stove on 03/16/2013 18:51:22 MDT Print View

Kasey, as JP says, Ebay is a good source for Ti foil. I've gotten most of the Ti foil I've ever used on Ebay. TiGoat, Seek Outside, Suluk46, and a couple other cottage backpacking gear companies also sometimes stock it.

Nick, I've considered a larger number of smaller jets, but I haven't had time yet to try it.