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HitTheTrail
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PostSun Sep 13, 2020 8:29 am 
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Since it is too smokey to go outside I thought I would post something about gear. A lot of stove systems with heat exchanger cups are heavy, bulky and often have more capacity than you need. And replacement cups may not be available at all (and can be expensive).

To make a cup of coffee or reconstitute a dried meal, half a liter is usually fine. In addition, the cup is often made to couple with one specific stove. The solution to this problem is readily at hand. Lots of heat exchanger cups are available on amazon and can be quickly modified with a hack saw. Here are a couple of examples that are less expensive and are more compact or can be made that way:
Sterno Inferno stove
Tentock stove cup

Sterno Inferno cup cut to fit other stoves
Sterno Inferno cup cut to fit other stoves
Sterno cup with MSR pocket rocket delux. Cup and burner 6.7 oz
Sterno cup with MSR pocket rocket delux. Cup and burner 6.7 oz
Sterno cup with Snow Peak1 litemax. Cup and burner 5.6 oz.
Sterno cup with Snow Peak1 litemax. Cup and burner 5.6 oz.
Tentock cup cut to fit other stoves
Tentock cup cut to fit other stoves
Tentock cup with MSR pocket rocket delux. Cup and burner 7.6 oz.
Tentock cup with MSR pocket rocket delux. Cup and burner 7.6 oz.

Also, be careful with titanium cups when trying to melt snow without a few inches of water in the bottom of the cup to start with. It can melt your fins.

Jet boil titanium cup with melted fins from trying to melt snow.
Jet boil titanium cup with melted fins from trying to melt snow.

edit: the Sterno cut with the Pocket Rocket deluxe burner is only 6.7 oz not 7.6 oc
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Randito
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PostSun Sep 13, 2020 8:49 am 
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HitTheTrail wrote:
Also, be careful with titanium cups when trying to melt snow without a few inches of water in the bottom of the cup to start with. It can melt your fins.

One doesn't always have the luxury of "starter water" when melting snow.

When the pot is filled with snow and there is no water in the bottom, the first bit of snow that melts is absorbed by the snow above, leaving an air gap.

To avoid scorching the pot, instead of filling the pot with snow,  start with a small amount of snow add snow a bit at a time as it melts.  Tedious yes.
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Malachai Constant
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PostSun Sep 13, 2020 9:31 am 
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For snow melting liquid fuel stoves still excellent due to low temps. In a pinch you can use a reactor for limited water as it heats the cartridge.

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"You do not laugh when you look at the mountains, or when you look at the sea." Lafcadio Hearn
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RumiDude
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PostMon Sep 14, 2020 12:52 pm 
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HitTheTrail wrote:
Lots of heat exchanger cups are available on amazon and can be quickly modified with a hack saw.

I use a Dremel tool for that sort of work. I have found it is easier and more precise than a hack saw. Of course I already had a Dremel for use with other stuff. I would not buy one just for a project like this, but since I already have it ...

Anyway, I have been thinking of trying this though I am reluctant to modify a pot and end up screwing things up. But the smoke and Covid have me a bit further on the stir-crazy spectrum than I normally am so who knows.

Rumi

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"This is my Indian summer ... I'm far more dangerous now, because I don't care at all."
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InFlight
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PostMon Sep 14, 2020 2:27 pm 
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The Sterno Cup is 6.7 ounces (194 grams) and has a 16 ounce capacity (475 ml).  A plain Titanium 500 ml Evernew Pot is 74 grams (2.6 Ounces).

The typical fuel canister has 100 grams of fuel, and the empty cylinder is 94 grams (3.57 & 3.32 Ounces).

With a JetBoil I could boil around 40 cups per canister in warm weather.  If we assume a regular pot is 30% less efficient, it would have 28 cups per canister. 

For a one week trip, assuming 4 cups of water boiled per day

Sterno Cup
194 Grams
Fuel Used    70 ml
Extra Fuel    30 grams
Canister      94 grams
Total:        338 grams  (11.9 Ounces)


Ti Cup
       74 Grams
Fuel Used   100 ml
Extra Fuel   0  grams
Canister     94 grams
Total:        268 grams (9.45 Ounces)

Thus on longer trips the heat exchanger equipped pots will make up for the extra weight with reduced fuel use.  The TI pot would need an extra canisters or a larger one.  For shorter trips the TI pot saves weight.

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HitTheTrail
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PostMon Sep 14, 2020 2:35 pm 
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RumiDude wrote:
I use a Dremel tool for that sort of work. I have found it is easier and more precise than a hack saw.

Actually, I have a Dremel that my wife bought me years ago but never used it much. Not even sure I know where it is now. How do you get a Dremel to cut a straight line like a hack saw?

Also, I think you and I have vastly different philosophies about making mods to gear. If you are reluctant because you might screw it up you probably shouldn't do it. When I get new gear I always look for ways to make it more usable, having it turn out different than planed is a cost of pursuing my hobby. YMMV.
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HitTheTrail
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PostMon Sep 14, 2020 3:08 pm 
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InFlight,
Thanks for the comparison analysis and data. I generally do one night/two day trips and only use a stove to make a couple cups of coffee in the morning. My little Ti coffee cup that I pour hot water into and drink from is around 400ml. That takes 6g of fuel to boil, so I get around 16 cups of coffee from a canister. I don't like bulky items in my pack so there is no way I need a 1L heat exchanger cup. That's why I usually cut them down to 500ml or less. Not to save weight but space.

Also, I have several Jetboil Ti cups that I cut down and have been using for the last several years(one of them is pictured in this original post with melted fins). I always got white foam on top of the water as it started to boil and thought it was coming from my hydrapak water bottle. I treated the hydrapak with lemon juice as people suggested and even tried different water bottles, but the foam would still form. I just recently discovered it was coming from the Titanium cup. It was some kind of oxidation reaction I guess.  Going to an aluminium cup solved the problem.
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RumiDude
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PostTue Sep 15, 2020 4:06 pm 
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HitTheTrail wrote:
How do you get a Dremel to cut a straight line like a hack saw?

I go slow. It's pretty easy for me to control that way.

HitTheTrail wrote:

Also, I think you and I have vastly different philosophies about making mods to gear. If you are reluctant because you might screw it up you probably shouldn't do it.

The main difference may be one of expendable funds. As to how that pertains to a project like this, I would note that the heat exchanger and shield on most of these pots appears to be attached via spot welds. Spot welds are often problematic and in applications such as this are dependent on each other. So with limited funds, I am reluctant to ruin something like this.

I'm also always trying to pass gear I no longer use to other people rather than landfill it. So if I make something that is fairly unuseable, I can't pass it on. Additionally, if gear is modified the warranty is most likely voided. That would apply mainly to higher end gear like tents, packs, sleeping pads, etc.

So yea, we have a different philosophy about modding gear. It's not to say I never do it, just that I am reluctant to experiment too much. I'm conservative in that aspect.

But as I said, I have a pot that I think I can use to modify without making it otherwise unuseable. So I might get out the dremel and see what I can do.

Rumi

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"This is my Indian summer ... I'm far more dangerous now, because I don't care at all."
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RumiDude
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PostSun Sep 20, 2020 3:46 pm 
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OK, I got the Dremel out and modified a Primus pot that came with this system. I used my Snow Peak LiteMax stove with it. I boiled 0.5 liter of 37*F water in 2:09 seconds. There was little to no breeze, so not much of a test with that. I had the stove wide open, which I seldom ever do. I did not weigh the canister but I am sure it used less than 8 grams of fuel. The canister was near empty.

Anyway, I would say that is clearly a huge success given the temp of the water and the resulting time. The downside is that it is not easy getting the pot on and off the stove. I sat the pot on the stove, turned on the gas, and then lit it. It's a bit more difficult that way.

If this saves fuel, which it seems likely, this setup will be my new favorite. The pot weighs 138 gms/4.9 ounces.

Rum

UPDATE: I did another boil test, this time in slightly breezy conditions, 0.5 liter of 37*F water and the time was 2:33 using 8 gr of fuel. The valve was completely wide open. I think that is overkill as it could just be half way open and still have a vigorous flame.

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HitTheTrail
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PostSun Sep 20, 2020 7:08 pm 
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RumiDude wrote:
The downside is that it is not easy getting the pot on and off the stove.

But that is actually a plus not a downside (in my humble opinion). It means you can pick up the entire stove and cup as one unit and pour hot water into a cup or instant meal without worrying about the cup falling off or burning yourself by trying to hold the cup on the stove.

Glad you tried this mod and had it work out for you. up.gif
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