Capillary Hoop Stove discussion

[squeezebox]

I was in the international market a while back. I was rummaging in the Mexican freezer isle. I saw sheep pizzle, and then picked up the beef pizzle, heavily wrapped in plastic. It was about 18" long and about 1" in diameter. The middle aged Mexican worker was a few feet away. I asked her if this was what I thought it was. She laughed at me and walked away. I did not buy it or put it in my mouth.

[squeezebox]

I was in the international market a while back. I was rummaging in the Mexican freezer isle. I saw sheep pizzle, and then picked up the beef pizzle, heavily wrapped in plastic. It was about 18" long and about 1" in diameter. The middle aged Mexican worker was a few feet away. I asked her if this was what I thought it was. She laughed at me and walked away. I did not buy it or put it in my mouth.

So much for the amigo aisle!

[aero-hiker]

It's in the Asian markets here. @aero-hiker - look up Lotte, H-Mart, Great Wall, etc.

Thanks! I'll check H-Mart.

Btw "squashing" the ribs and using Heet seems to have been a large improvement!


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[bnolsen]

It's in the Asian markets here. @aero-hiker - look up Lotte, H-Mart, Great Wall, etc.

Walmart here sells starbucks double espresso shot 4 packs. Those look like good candidates for eCHS for both rim diameter and depth of the collar.

[aero-hiker]

Yeah, I actually just finished drinking one. The upper rim seems like it is a little bit smaller than I would like, but I could always give it a try.


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[BirdBrain]

A candidate can for an eCHS must have the outside diameter be as close to the rim diameter as possible as illustrated on this video capture from a TetKoba video.

eCHS-Japan.jpg

In the USA, this can comes as close as you can get.

Milo-8oz.jpg
That can is the best I can find for the collet. For the body, I find the 5.5oz V8 cans to be about as good as it gets. Red Bull is to thin.

v8-5.5oz.jpg
It is possible that I have not looked at every Starbucks can on the market, but I am yet to find one where the rim to can diameter are close enough to work. As OMO stated, hold 2 of the cans against each other. The rims need to be almost touching. The closer they are the better. As the gap increases, the can becomes impractical to use.

Having said all this, I did not type all this to say you are wrong. I typed it for the sake of clarity and to find out if there is another can on the market that will work. OMO has listed a few other options that are not available in my area.

Update: Went to store. Checked out the small Starbucks cans. They seem to be very similar to the V8 cans. Therefore, they should work as good as the V8 cans. bnolsen and OMO already knew that. Just wanted to acknowledge that they were correct.

[Odd Man Out]

I have seen the starbucks cans. they look to be pretty similar to the to V8 and Ocean Spay cans. I may have made a stove out of one, but I don't recall.

I saw some Japanese cans of green tea in the store the other day. They have rims that touch, but the label says they are to be recycled as steel (must be a Japanese designation, doesn't look like the US recycling label). Anyone know if there are such a thing as steel cans of this size? Maybe I will cut into one tonight.

[BirdBrain]

I have seen the starbucks cans. they look to be pretty similar to the to V8 and Ocean Spay cans. I may have made a stove out of one, but I don't recall.

I saw some Japanese cans of green tea in the store the other day. They have rims that touch, but the label says they are to be recycled as steel (must be a Japanese designation, doesn't look like the US recycling label). Anyone know if there are such a thing as steel cans of this size? Maybe I will cut into one tonight.

I built one out of the very can you describe. It is made of a steel alloy. It did not work well. It was very difficult to construct. Beyond that, The stove did not run right. I am convinced the high rate of thermal conductivity of aluminum is largely responsible for the balance in the hoop. I also believe it is why the Toaks Siphon Stove does not produce the pretty blue flame seen in a typical eCHS. I will take a picture of the stove I built out of that can and the can I used in a few minutes.

Here are the pictures:

~

~

On a side note, it is absurd how many variations of this stove I have built. I am glad to be beyond that obsession. It is likely I will never build another stove. I have too many obsessions. Some are retired as I gain new ones (obsessions that is).

[BirdBrain]

Forgive my zeal. It is likely there is no other place to share my findings on such testing. It is possible that few, if any even care here. However, for what it is worth, I just lit my steel eCHS again to refresh my memory of the issues with it.

Before listing them, it is pertinent to state that I built it as best I could to the parameters of the best stoves I was able to construct out of aluminum cans. I felt it would be wise to change only one detail at a time. Although I tried to follow the construction dimensions of my favorite stoves, the material made it difficult to replicate an aluminum version. I had to abandon any thought of a secondary hoop at the bottom. Now to the operational issues.

The stove bloomed very fast. That was likely the only positive.

Although I did my best to make the ribs the same size, the jets were very unbalanced. One side rose much higher than the other. This is the first distribution of heat issue with a metal of lesser conductivity that was evident.

The fuel in the bowl boiled eventually. This is counterintuitive and speaks to the mechanics of what is happening in the ribs. It would seem logical that a material that transfers heat faster (aluminum) would heat the fuel in the bowl faster than material that transfers heat slower (steel). However, that is not what is happening in a CHS. I won't entirely revisit that here. It is discussed in detail earlier in this thread. Suffice it to say, unlike other jetted alcohol stoves, it is not desirable to have the fuel heat in the bowl. The fact that the fuel heats faster in a steel eCHS than in an aluminum eCHS reaffirms (at least in my mind) that the fuel in the ribs is trying to quench the heat. It has more success with aluminum than steel.

When the jets ebb, the stove continues to run for a long time in the bowl. Because the whole stove is hot as the jets ebb, there is little incentive for the fuel to go up the ribs. In order for the fuel to be wicked until almost gone, there needs to be an imbalance of temperatures in the stove. The greater the difference in temperatures between hoop and bowl, the greater the percentage of fuel that will be burnt before the jets go out. This detail should encourage eCHS users to not worry about carrying a shielding for the bottom of their stove. I carry none.

As to the performance, my steel stove had more power, burned the fuel faster, and was less efficient than my aluminum stove. I am going out on a limb and say a titanium version would suffer even more. It is possible that changing the construction parameters could result in better performance. However, my steel version was so hard to construct, I will not be finding out if that possibility exists.

But yah. To those that care. Thanks for indulging me. Maybe my words save you some grief or point you in a direction of success in building a steel version.

[aero-hiker]

Thanks for the tips. I am searching hi and low for Nestle Milo and will likely stop by H-Mart on my way to Dutch's open house Saturday.


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[bnolsen]

Thanks for the tips. I am searching hi and low for Nestle Milo and will likely stop by H-Mart on my way to Dutch's open house Saturday.

definitely seen those cans in hmart. i happened to work in an office building next door to the local hmart.

[Odd Man Out]

OK, so those steel cans don't work. Anyone want to buy a can of green tea?

[squeezebox]

At least playing with beverage cans is better then watching TV reruns.

[aero-hiker]

BB and OMO: I finally got some Nestle Milo cans at H Mart. Do you guys use those for the tub AND the collet, or just the collet? I seem to recall BB suggesting V8 can for the collet. Is that correct?


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[BirdBrain]

BB and OMO: I finally got some Nestle Milo cans at H Mart. Do you guys use those for the tub AND the collet, or just the collet? I seem to recall BB suggesting V8 can for the collet. Is that correct?


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Collet is inner/top piece. Body (tub) is outer/bottom piece. Use Milo can for collet. Use V8 can or any can that OMO has mentioned for body. Do not use Red Bull for either part. It is too thin. The diameter of the rim on the Milo can is as large as you can get on these small cans. this makes for a better seal when inserting into the body. The bottom of the Milo can is not a good choice for a body. The shape makes for huge tabs. Also, the Milo can makes a nice hoop. It is slightly larger than other choices. Ideally, the hoop would be slightly larger than even the Milo can. It can be enlarged. It is a PITA though. A slightly larger hoop makes for easy control of pressure in hoop. Ideally, there should be very little pressure in the hoop.

The fun begins. Take it slow. Be precise. Crush the failures. Or mail them to friends.

[Odd Man Out]

What he said. I have not found a Milo can yet.

[Maui Rhino]

Over the weekend I made 3 CHS-U stoves...2 were made from 5.5oz V-8 cans, and the 3rd was made from heavier aluminum Sprite bottles. They had the same diameter as the V-8 cans, and all stoves were made to the same overall dimensions. Jet size was 1/32 (~0.78mm) because that's all I could find locally.

My first attempt using the V-8 worked okay, however some of the jets weren't well defined, and one seemed to be blowing more straight up, with the vortex of flame centered over the edge of the can, instead of the aperture. My ribs were crude.

#2 was much better. Jet flames were more defined, and ribs were more defined and even. Overall, construction was easier than my first stove. On one jet, with a less defined flame pattern, it appeared that a secondary flame was coming from between the two pieces of the collet and jet deck, inside the aperture. I assume there is a slight gap, although visually, they appear to be solidly pressed together.

#3 with the aluminum Sprite bottles did not turn out well. Construction was more difficult, requiring more effort to cut. Shaping the ribs was very difficult due to the heavier material. I resorted to carving a grooved block of wood for inside the can, and a triangle file, pressed together with an adjustable wrench. I was unable to make nice creases in the top rim, which I suspect reduced fuel flow. The stove burned weakly, with more yellow flames, and never formed defined jets (reached full bloom). Burn time (~12min) was also longer than the first two stoves (8.5-9min). The fuel also boiled in the tub as the stove burned, similar to the description above about the steel stove. Press fitting the three pieces together was also much more difficult than with the V-8 cans, which I did using only finger pressure. With the Sprite bottles, I was forced to use a dowel to push the collet fully down into the tub. This deformed the rim of the inner apeture, and may have impacted burn time.

Overall, I learned some things and had fun. I'll be making some more as soon as I drink some more V-8. I may try sealing the rim between the collet and jet deck with JB Weld also.

[BirdBrain]

You are correct. There is a gap between the folds on the inside of the rim. Burning under the rim is normally a sign that the aperture is to large. It is normal to have some bending of the flame near the aperture. Upward convection caused by the flame and wicked fuel in the collet create a vacuum in the bowl. This vacuum must be satisfied. Some air will flow into the bowl. Some of the turbulence you see in the flame is that air going into the bowl. If you are inclined to fill that gap, it can be done from underneath. That method requires a lot of jb weld and will increase the weight of the stove. Another method is to drill the holes, extrude jb weld back through the hole via wiping with finger, let dry, and redrill the holes. If the stove is built right, it is not necessary to worry about that gap. One jet being weak is a sign that a nearby rib is flat or too large. Try to make ribs as uniform as possible.

[aero-hiker]

For my CHS-u I used a very small quantity of JB Weld between the jet-deck and rib-collet. I didn't see any leaking from this junction of the hoop.


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[aero-hiker]

Just found an interesting video on an alternate design/can-type eCHS from Silvio De Leonardo. https://www.youtube.com/watch?v=vscWNXrtoBg This stove has inwards pointing jets, like the original CHS unlike his other CHS video. Didn't mean to add fuel to the fire, but just thought I'd post it here. I may try to build it if I can find the right Axe can, and a scent that I can stomach...