Modified Coleman Xtreme Stove

[Bill Fornshell]

Richard, Don’t ask me how many I bought at the $2.99 price. I can say that I did leave one for the next person.

There has been a good Thread on the Xtreme stove at the backpackinglight yahoo group the last couple of days. Information a little on the technical side but not to deep. I have learned a few good things about how the stove works.

I have decided to build my stove/stand set-up to take one of my Trangia cook pots. I have two that are about the same size (1.5L & 1.75L) but one is a little deeper. I might go to a Titanium pot of the same size later.

Mike, your pictures are great.

[kevin davidson]

Bill–from what I read from Mike M. over in Yahoo Groups and taken with Curt’s own cutting to the bone— would you say that the biggest weight reduction possibilities, apart from ditching the Magnesium fin housing, would be in creating a Ti stand for the burner assembly? Or can you fabricate lighter parts for the assembly, as well? Is the burner bowl a throwaway?

[Bill Fornshell]

Hi Kevin, Lets start with the Burner Bowl. The stock burner bowl weighs 25.2gr. I have made a replacement out of aluminum that weighs 6.3gr. Is it a throw away, with my 6.3gr version, not yet. Will my lightweight version do what the heavier stock item did I don’t know yet. It might melt.

The Valve & Hose Assembly. I still need to take this apart and see what is inside it. then I will see how much I can trim it to reduce it’s weight of 135gr. Because I am working on this stove as a primary tool for melting ice/snow at a very low temperature I don’t want to degrad the ability to attach the canister to the gas line and control the stove between 20 degrees F and -20 degrees F. At this temperature you will need to do everything in gloves or mitts. More on this later. It would be nice to reduce the Valve assembly by 1/3.

How this stove looks when I am finished is still not clear. If you think of the Jet-Boil as a stove system I want my finished product to be a stove system also. That means everything built-in but with a cook pot that is put into and taken out of the stove system.

If I was making a mild season stove I could make a nice danty set of Titanium legs that weigh very little and a stove easy to use without gloves or mitts. That is not the current goal.

[kevin davidson]

Bill, I have not forgotten the need to be able to use this stove in Winter—-indeed, it’s the only time I would ever use it unless I get into high altitude climbing again. But it sounds you feel there is still ample room to put the Xtreme on a diet.

I’ve not actually had the privledge to have used a stove I could really operate with my mitts. Generally speaking, I have found liners, thin or thick, adequate in the depths of Winter. It’s a matter of controlled exposure.

I have heard of stoves modified for Antarctic or High Arctic use with oversized controls and fittings for use with uber mittens.

I guess I don’t understand why very light Ti legs would not be adequate for the intended use—-particularly if rod stock was used.

[Paul Luther]

Bill and Richard,
Thank you for your replies. I’m in Buffalo, NY. I’ll check the local Gander Mountain for Coleman Xtreme stoves and canisters. Thanks for the info on the Coleman outlet website.
Paul

[Bill Fornshell]

Kevin said: “I’ve not actually had the privledge to have used a stove I could really operate with my mitts. Generally speaking, I have found liners, thin or thick, adequate in the depths of Winter. It’s a matter of controlled exposure.”

You are correct, liners would have been a better word to use. I have several different kinds to include some Possum Down liners from BMW. I have been in the White Mt’s when it was below “0” F. and my fingers would get cold fast outside my Mitts even with liners. My liners today are selected as carefully as I pick my mitts. Experience is a hard teacher at times.

I will know more about the Valve Assembly before the day is over. I am about to put it on the operating table.

[Richard Nelridge]

Bill,

Keep us posted on the updates. Looks promising and hopefully the patient will survive the operation.

Rich

[Joshua Mitchell]

Last I checked Mcmaster was one of the more expensive options for Ti Rods.

A couple of sources:

Online Metals
Grade 2:$2-3/foot

Grade 5: $12/foot

OR

Solid Graphite Rods?

[Bill Fornshell]

I have taken the Valve Assembly apart. Three screws and the “Heat Sink” part of the Valve comes apart/off the valve assembly. It looks just like Curt’s pictures when the Heat Sink part is removed. I really thougt there would be more to it.

I thought Curt or Mike posted the weight of the Heat Sink but I can’t find it. I get it as 47.6gr/1.67oz. The rest of the Valve and Hose Assembly weighs 84.3gr/2.97oz.

The first thing I am going to do to the heat sink is to remove all metal that isn’t necessary to hold it together or hold the canister/Valve connection. In the cold temperatures I am making this for I think it would be nice to have something to hold onto when connecting the PowerMax canister to the valve Assembly. What you can’t really see in the pictures is the black plastic parts(2) that the canister connects to. Without the heat sink those two part have nothing to hold them together. I should be able to drill or cut away half or more of the heat sink.

The second area where I might be able to reduce some weight is by making the braided stainless steel? line shorter. I will have to visit one of my local “Hot Rod” shops and see who can do something like that.

I am still not real sure I know what the Heat Sink part is doing. Trying to displace cold from the gas canister or hold heat. The fins would lead me to think they are made to displace something and not hold it.

In one of the pictures to follow you can see the new Burner Bowl I made. The cup shown (is/was) a Poached Egg Cup. I eat really well most of the time when hiking. I do have a very light weight kitchen kit when I want to go SUL.

[Michael Martin]

Nice Photos, Bill!

The heat sink transfers heat to the fuel from the air. What I don’t know for sure is whether this is just during startup or simmering, or maybe during warm weather operation where the fuel might vaporize just downstream of the valve.

Your bowl looks great, but I expect the stove would work just fine without any bowl at all.

What did you do to your poor pre-heat tube? That thing looks like a pretzel. :-O

Cheers,

-Mike

[Bill Fornshell]

Thanks Mike,

I guess what I am after is just what does the heat sink do for the stove at “0” degrees? How cold do you think the gas coming out of the canister is? Is it colder than say the outside temperature at “0” degrees or less? I guess there is a point when “0” F might seem warm. Then I have to go back to my main concern and that is the ease of doing thing when it is really cold.

I think you are right about the Burner Bowl. Since I had an extra little cup I just went ahead and made it. My fear is that the heat might melt it.

The Pre-Heat Tube, you just had to ask that question didn’t you? It got a little “bent out of shape” when I was trying to take things apart the first time. I had a little trouble finding a tool that I could get into the little hole on the lower part of the burner assembly. I should be able to striaghten it up when I am done messing.

[Michael Martin]

Bill writes:

>> How cold do you think the gas coming out of the canister is? Is it colder than say the outside temperature at “0” degrees or less?

The long answer:

If it’s warm enough in the braided tube that the gas vaporizes before getting to the pre-heat loop, then the gas in the tube will be *much* cooler than the canister temperature due to evaporative cooling of the fuel. The fins would then serve to warm the fuel from the surrounding air and keep it vaporized. Just guessing, but I can see this happening during warm weather operation, simmering, or startup.

But, at full throttle at zero degrees, I don’t expect there will be much of a pressure drop across the valve (the big drop should occur at the jet). So, (and I’m really just guessing again) I expect that at 0 deg F, the fuel won’t vaporize until it gets to the pre-heat tube, and until then will remain liquid at about whatever temperature it was inside the canister. [Of course, this assumes that the pre-heat tube has not been mangled beyond all recognition.] <g>

The short answer:

My best guess is that the fins don’t do squat at zero degrees once the stove is warmed up and roaring. Priming/Simmering is another story.

[Bill Fornshell]

Hi Mike,

Before

After

How about a longer pre-heat tube that runs all the way around the burner bowl or burner head?

[Curt Peterson]

Looks like your surgery has begun, Bill. I’m excited to see where this all ends up!

I agree with Mike that the burner bowl isn’t necessary at all. In fact, I believe it’s actually labeled a “windscreen” in the Xtremem blown-up diagram I remember seeing at some point. I’d use a windscreen regardless, so it was redundant.

I also think the fins are probably useless once the stove is running. If I remember right, the directions say to turn the stove on very low for the first 30 seconds or so, then go ahead and crank it up. This should give the pre-heat tube plenty of time to warm up – even in really cold conditions – and at that point I can’t imagine the fins do anything.

I’m not sure what the temps were on Adams when I had my Xtreme “epiphany”, but I had a 10 degree bag and froze my ass off. Early in the morning is when the Xtreme was doubling (at least) the output of the Whisperlite. Probably somewhere between 5 and 20 degrees.

Any lightbulbs on the stand yet??

-Curt

[Michael Martin]

Bill writes:

>> How about a longer pre-heat tube that runs all the way around the burner bowl or burner head?

I don’t think a longer pre-heat tube is needed. A longer tube is used with a white gas stove because the fuel vaporizes at a higher temp. A smaller preheat tube can be used with propane/butane.

BTW, that’s a stunningly beautiful preheater you’ve got there. ;-)

Cheers,

-Mike

[kevin davidson]

It’s like watching “ER”. I can almost feel the cuts.
What we need is a webcam. ;-)>

I have heard similar re. vaporizing temperatures (MM’s observation). I also think a longer preheating tube would only make the unit more fragile.

[Roger Caffin]

What I would love to see is the interior of the control valve. Is this just a standard needle valve?

[Roger Caffin]

Bill: have you thought of making up a small plastic substitute for the magnesium ‘head’? Lightweight, but much easier to handle. It won’t be melting. It would also locate the canister neck.

[Roger Caffin]

What does the black control knob weigh? It should be possible to make a UL T-bar replacement?

[Bill Fornshell]

Roger Asked:
Q1 – What I would love to see is the interior of the control valve. Is this just a standard needle valve?
A1 – Is this what you are asking about?

Q2 – Bill: have you thought of making up a small plastic substitute for the magnesium ‘head’? Lightweight, but much easier to handle. It won’t be melting. It would also locate the canister neck.
A2 -Yes, but. The “head” weighs 39.6gr/1.4oz. (knob removed). I will drill it out and remove as much metal as I can first. I hope to reduce enough weight that making a substitute would not be worth the time. I would like to retain the ability to hold the canister connector and valve assembly with a much reduced stock unit.

Q3 – What does the black control knob weigh? It should be possible to make a UL T-bar replacement?
A3 – The black knob weighs 8gr/0.28oz. I will first drill some holes in the knob and see how much weight I can reduce that way. I agree that a replacement could be made. If I can reduce the weigh by half I may keep the knob.

[Bill Fornshell]

I found out today much trouble it can be to drop 3.6gr/0.13oz. I was able to remove the Hose from the Valve & Hose Assembly. The braided SS line has a black tube something in it that looks a little like filter material. I cut the braided line in half leaving it 3″ long. Anyway, it was far more trouble than it was worth.

My local Hot Rod shop gave me a little help by cutting the line with a really neat piece of equipment. They custom make a lot of Stainless Steel lines and couldn’t believe I would do all that work to save 3.6gr. I reminded them that some of what they did to their cars is also very time intensive. They have just returned from the Bonneville Salt Flats and a speed record attempt for there class. I just asked them if they used a check list and how many times did they go over it before each run.
They have a really nice milling machine and I might use it to remove material from the Valve Casing. I will have to make a chuck to hold the casing first. I may be able to do it with a flex shaft on a drill but I still need to mount it on something.

[Michael Martin]

Hi Bill-

Nice photos as usual!

Can you tell if there is anything interesting in the fitting between the braided tube and the solid tube? I’ve always wondered if the wire inside the solid tube performs some kind of valving or throttling function with how it mates with the fitting. I’m thinking it *might* work as a 1 way valve to temporarily shut off the fuel supply if the pressure in the preheat tube got high for some reason.

[Roger Caffin]

> Q1 – What I would love to see is the interior of the control valve. Is this just a standard needle valve?
> A1 – Is this what you are asking about?
Yep, thanks.
OK, standard needle valve. Hum – interesting. Thoughts which follow:

The needle valve is valving liquid. Consistent with performance. So liquid is going up the tube to the stove. It vaporises up there.

Other remote cartridge stoves are similar, but withOUT the big wire up a straight bit, and they work. I think the wire is simply an attempt at a heat exchanger, feeding back from the burner. Since other stoves don’t have one, …

Other stoves, like the Snow Peak GS200D, can be used with liquid feed. They do NOT have a massive lump of metal around the valve. So I think the beautiful finned diecast magnesium housing has the following functions: something to hold when you are mating the canister to the valve; something to protect the plastic clip which holds the canister; a stylish bit of marketing. Deduction from all this: you could safely leave the whole magnesium bit off. (I think …)

Apropos of other remote-cartridge stoves: I think it should be possible to make a stand which will hold a conventional cartridge in an inverted position so the valve can be easily adjusted. This means any remote-canister stove could be used. I will experiment, and report.

How did you get the pictures into the email???? If I succeed with the above, I may be able to post a pic of it.

[Bill Fornshell]

Mike asked:
Q1 – Can you tell if there is anything interesting in the fitting between the braided tube and the solid tube?
A1 – This looks like a standard “crimp” used to connect a tube and a braided hose. Remember the black (whatever) that is inside the hose. It looks sort of like a filter material, somewhat like the old style cigarette filter. A Coleman enginner said this material helps slow down or regulate the gas flow. I hope to get a call from him sometime next week. He was given BPL web URL to have a look at what we are doing. When you measure the brass rod that goes into the brass tube part of the hose and measure where the black stuff starts in the braided part of the line there doesn’t seem to be any space for something else.

Q2 – I’ve always wondered if the wire inside the solid tube performs some kind of valving or throttling function with how it mates with the fitting. I’m thinking it *might* work as a 1 way valve to temporarily shut off the fuel supply if the pressure in the preheat tube got high for some reason.
A2 – Heres is what I know about that brass rod:
– It is 3-5/8″+ a very small amount long.
– It is the same size (1/16″) as BPL Ti rod.
– It weighs 1.9gr
– It slides freely in and out of the brass tubing connected to the braided SS hose.
– It will slide into the brass fitting that the pre-heat loop tube is connected to about 3/8″.
– Gas pressure from the canister will move the brass rod, case in point, when the gas pressure blew the brass rod out of the end of the brass tube part.
— When the pre-heat tube is “hot” how much do you think the brass rod might expand? If the brass expanded it might act as some type of flow control.

Roger Said:
[1- R] Other stoves, like the Snow Peak GS200D, can be used with liquid feed. They do NOT have a massive lump of metal around the valve. So I think the beautiful finned diecast magnesium housing has the following functions:
1- something to hold when you are mating the canister to the valve;
2- something to protect the plastic clip which holds the canister;
3- a stylish bit of marketing.

[1-B] I agree.

[2-R] Deduction from all this: you could safely leave the whole magnesium bit off. (I think …)

[2-B] In warm weather I think your idea would work. For use in very cold weather I don’t think I would remove it.

Q-How did you get the pictures into the email?
A- You need to upload your pictures to a site such as Photobucket.com. They then provide the link to BPL.com or other places on the web. You do a copy/paste of their URL from Photobucket to BPL.com. Photobucket is a free hosting service for 500 plus pictures.

[Roger Caffin]

> 2-B] In warm weather I think your idea would work. For use in very cold weather I don’t think I would remove it.

Needs testing. But I have used other remote canister stoves like the Snow peak GS 200D in the cold. Light carefully, at low setting, so the preheat tube warms up without a fireball.

Question: I have lost the URL you gave somewhere to your blog with the balloon airbed. Can you repeat? Please!

[Author]

Posts