Modified Coleman Xtreme Stove

[Michael Martin]

Roger writes:

>> The needle valve is valving liquid….So liquid is going up the tube to the stove. It vaporises up there.

Roger, at full flame, in cold weather, I definitely agree with you. But at a low-heat valve setting, say at startup, or during a low-heat simmer, there would be a larger pressure drop right at the valve. Especially in warm weather, I expect some (all?) of the fuel might vaporize just downstream of the valve due to this drop.

If this were true, the fins would serve to conduct heat from the outside air into the evaporating fuel, providing the necessary heat of vaporization.

From a design standpoint, I think this would be desirable during startup where the pre-heat tube is still cool. The fuel still needs to vaporize before it reaches the jet to mix with the air, and the fins would help this process — reducing the chance of a fireball, as you say. Also, during low-heat simmering, it may be advantageous for the fuel to vaporize right at the valve to allow better flame control and reduce sputtering. (Both of these issues are probably irrelevant for full-throttle Winter snow melting.)

If a mixed-phase fuel were sometimes present in the fuel line upstream of the pre-heat tube, it might offer an explanation for the “wire” and “filter material” in the fuel line. Both of these mystery components might serve to smooth out the flow of a mixed-phase fuel to reduce burping and sputtering.

All of this is sheer speculation, of course. What we need is a transparent fuel tube so we could watch the fuel vaporize on it’s way to the burner…

Cheers,

-Mike

[Bill Fornshell]

Roger:
Here is the URL for the Poly-Tube DAM stuff. It is on 4 different pages. If you look at the top of the page you will see “SEARCH THIS BLOG”. Click there and it will take you to a list of the other pages. It is long and drawn out. This was a collection of posts/questions/answers that ran about a year.

DAM Blog

[Roger Caffin]

> Especially in warm weather, I expect some (all?) of the fuel might vaporize just downstream of the valve due to this drop.
To be sure, it would.

> If this were true, the fins would serve to conduct heat from the outside air into the evaporating fuel, providing the necessary heat of vaporization.
Good theory, but I suspect the amount of energy input via the mag block would be small. The canister would do just fine imho. After all, upright stoves do work in ‘warm’ weather’.

> From a design standpoint, I think this would be desirable during startup where the pre-heat tube is still cool.
But the whole fuel line and burner have heat capacity, and would warm the fuel far better, and once the flame is there, who needs any other heat source?
This works with other stoves.

Yeah, a clear tube might be interesting – but then it would have a different thermal mass. Hum.
More playing needed.

[Michael Martin]

>> Good theory, but I suspect the amount of energy input via the mag block would be small.

I agree. But it does perhaps double the surface area of the whole fuel tube apparatus. Maybe it reduces ice formation on the outside of the fuel line????

>> The canister would do just fine imho. After all, upright stoves do work in ‘warm’ weather’.

Ahh, but in an upright canister, the thermal mass of the liquid fuel remaining in the canister buffers the cooling effect. In a liquid-feed setup, the cooling would be dramatic in the fuel line until the temperature became too low for the fuel to completely vaporize upstream of the pre-heat tube. Also, in an upright setup, the canister itself can absorb heat from the environment, while the Xtreme canister is insulated by the black platic thingies from the fuel line (and preheat tube) where the evaporation takes place.

>> But the whole fuel line and burner have heat capacity, and would warm the fuel far better, and once the flame is there, who needs any other heat source?

We agree again. Hence, you can operate a conventional canister upside down. But, does it light easily and reliably? Can it simmer without sputtering out? The Coleman stove is designed for liquid feed and mass-market use. So perhaps it has these extra design details, that while not necessary for our Winter snow melting task, make it more user-friendly for the mass market.

BTW, Roger, as an engineer, I’ve really enjoyed your writings on bpl and your Aussi site. Thank you for your comments on this forum! Being able to have an exchange like this with someone of your credentials (or Ryan’s for that matter) is one of the best things about BPL.

[Roger Caffin]

Bill

I have taken over as Stoves Section Editor at BPL from Will R. My bio will appear one day on the masthead …
In the meantime, I wonder if you would be willing to contact me direct? Probably a breach of whatever on this forum, but my address will be public soon anyhow. My email is (I think):
[email protected]

[Roger Caffin]

> > Good theory, but I suspect the amount of energy input via the mag block would be small.
> I agree. But it does perhaps double the surface area of the whole fuel tube apparatus. Maybe it reduces ice formation on the outside of the fuel line????
‘reduces’ is unlikely: the whole lot would be way sub-freezing anyhow in mid-winter.

> while the Xtreme canister is insulated from the fuel line (and preheat tube) where the evaporation takes place.
If evaporation IS taking place in the fuel line, the ambient must be pretty warm. Butane boils at -0.5 C (31 F), while propane boils at -40 C (-40 F). It is quite possible that the propane boils off somewhere in that black tube Bill showed us and bubbles up to the jet at the start. But if it does, this leaves butane behind, and that is likely to be liquid, and so will reach the jet in liquid state.

> Hence, you can operate a conventional canister upside down. But, does it light easily and reliably? Can it simmer without sputtering out?
Experiment trumps theory every day. I stuck a Snow Peak GS200D in the freezer for a while, then took it out and lit it immediately with the piezo. Absolute delight to operate, as easy as the Xtreme. (So far, so good.)

You will be getting me as the Stoves Section Editor for a while on BPL. Sorry about that. :-)

[paul johnson]

Mr. Caffin,

Congrats on the editor position. BPL sure knows how to pick ’em. Good move BPL.

>>”Experiment trumps theory every day.”

three points:
1) obviously, the experiment must be properly set up.
2) decades ago, pioneer aviator, inventor, engineer, Igor I. Sikorsky was fond of saying to young engineers: “When the facts disagree with the theory, I urge you young gentlemen, to accept the facts.”
3) the “Rhiele Axiom”, states, “One Test is worth a thousand expert opinions.” Test Engineers the world over swear by this principle.

[Roger Caffin]

> Mr. Caffin,
> Congrats on the editor position. BPL
> sure knows how to pick ’em.
Let’s hope so!
But look guys – ‘Roger’ will do just fine. I get enough of ‘Dr Caffin’ when I am playing professional scientist, but not here, please!
Cheers
PS: yes, I do have a few special Features in mind for stoves on BPL. They will take a little while to be completed, but stay tuned.

[Michael Martin]

Hi Bill-

I saw your milling machine post on the Winter SUL thread and thought it would be more appropriate to discuss a few things here.

1) First, let me say that I have no experience machining anything. But, I’ve read that Magnesium is hazardous to work with — apparently the dust can ignite. I don’t know how real the danger is or what your background is. But, I felt compelled to bring it up. Please be careful.

2) On a brighter note… If your new machine works well, could I hire you to skeletonize my casing for me? If you’re interested, please email me at [email protected]. [thanks!]

Best Regards,

-Mike

[Bill Fornshell]

Mike, This stuff isn’t real Mag. I have worked with the real stuff and have a set of Real Mag wheels on a small very fast car I own. Talk about something being light.

Thanks for the warning about the Mag dust.

Anyway, as a potter I learned long ago to always wear a dust mask for what ever material I work with. I also have filed, scraped and a couple of things I don’t want to admit to with very little success on this Mag?? alloy.

Let me see how this “casting” works out and then we can talk about yours.

[Ryan Faulkner]

I just decided to test out stripping my MSR windpro canister stove.

but I am wondering, what do you use as a pot stand, and to keep the leggles stove upright?

I bet this has been mentioned, but I havent been reading this thread and I dont think there has been any pics of a stand.

[Ryan Faulkner]

without a pot stand, the stripped windpro weighs 4.7oz.
I also got it to work with a pocket rocket head, but this wont work well in cold temps because there is no flame heating the feul line, but it will work in the summer.
the striped stove with the pocket rocket head weighs 3.7oz.

[Ryan Faulkner]

Here is a pic of the windpro canister stove.

The 4.7oz stripped stove next to pot stand.

the 3.7oz stripped stove

4.7oz flame looks exactly the same as the stove with pot stand in action

[Bill Fornshell]

Rejected Idea for light weight legs for the Xtreme. I made a set of legs out of .016″ Titanium but when I put a pot with 1 liter of water on it the legs sort of fell over. I didn’t add a crease in the Ti for extra strength and the water was to heavy. I have tried other ideas but I am not happy with any of them yet.

I have made stove stands out of cat food cans and other aluminum cans but don’t like any of them so far.

I really think I want a separate stove stand and a separate cook pot stand.

Jason suggested a hanging system of some sort. This would work outside but I am not sure how it would work in a snow cave. The whole idea behind the “Diet” for the Xtreme was a stove that would be very good in the cold and be used to melt ice/snow for water on Ryan’s winter hike.

The weigh of the modified Xtreme is 6.26oz but it still has no stand for the stove or cook pot. I have reduced the weight of the Mag casting from about 1.7oz down to about 1.07oz a savings of about 1/3 from the orginal weight. I was hoping for more but not yet.

[Bill Fornshell]

I think I have reduced the Mag. casting for the Xtreme Stove as much as I can easy. I have each piece down to .507oz or 1.01 for the pair. I will see if I can file off the other 0.01oz to bring it to 1oz even. The stock casting was 1.68oz.

The pictures show the before and after. It still connects to the PowerMax Canister the same as in its stock form. I don’t want to change that.

The milling tool I got works nice.

[Bill Fornshell]

So it is finished. The Mag Casting has turned out to be .99oz for the two parts. The 3 steel screws that came with the unit weigh 2.4gr and I will look for something nylon or aluminum to replace the steel screws.

There was a question about doing a modification such as I have without a shop or special tools. I really think the answer is NO. The milling might be possible with a “flex shaft” drill system or maybe a Dremel type hand drill thing. I don’t own a Dremel tool so I can’t say for sure. I do know that my milling tool needs to be set on 20,000 rpm for the Tungsten Carbide Cutters I used.

The lighter burner head I am going to use needs a new aluminum tube to connect it to the fitting that has the pre-heat loop on it. The new tube (about 1-1/4″ long) needs to be threaded in two different sizes, both uncommen metric sizes. The two tap’s had to be special orderd and I hope to get them Friday. The burner head came off the Coleman F1 Ultralight Stove.

Then you will need to make a new lighter set of legs. I will start working on the legs for my stove on Tuesday.

Current weight without the legs is 6.18oz.

[kevin davidson]

Bloody impressive. I want one.

Are you planning on using the stock control valve handle?

[Michael Martin]

Beautiful!!!

Bill, you inspire me! (Although after seeing your gear, I may never get up enough nerve to post pix of any of my cobbled-together, rough-cut homemade projects….) My stuff looks like a kindergartener made it next to yours.

Cheers,

-Mike

[Bill Fornshell]

Thanks Kevin

Kevin Said: “Bloody impressive. I want one.”
Answer: Send lots of money.

Q-Are you planning on using the stock control valve handle?
A- If I stay with the stock knob (I think that is what you are talking about) I will try drilling a few holes in it.

Thanks Mike.

Mike said: “Bill, you inspire me! (Although after seeing your gear, I may never get up enough nerve to post pix of any of my cobbled-together, rough-cut homemade projects….) My stuff looks like a kindergartener made it next to yours.”

Never sell youself short. It is more important to get your ideas made, finesse’ can come later. I call everything I make a prototype till I am happy with it. We should all understand a prototype is a work in progress. I also don’t have a thin skin and like others imput. More sets of eyes looking at something has to be better than just one set of eyes looking. There have been times I didn’t have the material I wanted and my prototype even made me laugh. But the idea I was working on “worked” and later I found a better material.

[Ryan Faulkner]

I know how you feel mike.
my stove stand for my wind pro is a little crude, if you saw it in person, and looks like garbage compared to bills Ti stand, but it works great and is light so I dont care.

Im getting a sewing machine soon so my first few projects will be…
but I think I will get the hang of it

Bill good job,
the milling machine basicaly files things down right?

[Bob Gabbart]

Bill – Very impressive work! RE: The control knob. What about making a tensioned flip over wire control like on the Snow Peak and Vargo Ti stoves.

(picture from Roger Caffin’s review of the Snow Peak Ti GST-100 Stove)

It would just require drilling two holes in the side of the control axle and then bending a piece of Ti rod

[kevin davidson]

I concur with Bob about the control “knob” modification—very easy to use with the heaviest mitt.

[Roger Caffin]

Bob Gabbart wrote:
> The control knob. What about making a tensioned flip over wire control like on the Snow Peak …
and included a picture of the Snow Peak GST-100.

It might be polite to mention that you got this picture from my OR on the stove at BGT, at
WarthogBGTMyOldORsSnowPeakGST100SnowPeakGST100.htm
but I am not really fussed.

Cheers
Roger Caffin

[Bob Gabbart]

Sorry Roger. I’ve added a caption below the picture and added a link back to your review.

Bob

[Curt Peterson]

Bill,

Very nice work! At that size and weight, it’s worth keeping as it makes attaching the fuel infinitely simpler. I may try to duplicate this with some much more rudimentary tools. We’ll see….

By the way, you can drop another 0.2 ounces (7 grams) by losing the prop-up stand on there. It only serves to pool the fuel in the bottom of the bottle, but it works without it and there are about a million things that could replace its function (twig, small stone, dirt, etc.)

Can’t wait to see your stand solution!

-Curt

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