Caldera Cones – My Adventures in Improving the ULC system

Just a heads up that the 2g Terra Nova stakes don't work after all.

They're plenty stiff at normal temps, but this one got too hot and bent under the shared weight of a pint.

I have now switched to use two homemade stakes from that Ti rod I ordered which is a bit thicker (ie. 2.0mm vs. 1.7mm). Weight is up from 1.9g each to 2.2g.

Dan,

I know I'm a little late with this, but I had a Walmart pot that I didn't like the way the knob protruded on the top of the lid so I took it off, cut about a 2" long piece of 1/2"; webbing, folded it in half and pop revitted it thru the old screw hole. Makes a 1" loop to pick the lid up by.Lays flat for storage.

JJ

I have essentially the same pot set up for my 2-man trips. I have never used the fry pan lid. Rather, I bought a piece of 3/32" thick Lexan (polycarbonate) at the Home Depot and cut a lid for it. The lid lifter was simply a piece of griptease tied in a loop through 2 small holes at the center of the lid.

Sooo…that lid melted (but did not deform otherwise) at the points that were in direct contact with the pot. Nonplussed, I cut another lid from the same sheet just a tad smaller. I stole one of my wife's silicone hot pads and cut a narrow ring out of it. I attached the ring to the polycarb lid where it contacts the pot. Problem solved.

Much lighter and more compact than the 'frying pan' lid, and my alcohol stove and conical windscreen still fit perfectly inside with an 8 oz water bottle of fuel and a lighter.

Thanks for the info guys.

The lid issue has been on my mind for a while. What I really wanted to do was replace the 40g fry pan lid with a 7g carbon fiber lid from Ruta Locura, but they don't make one big enough for my pot, which leaves me with the heavier and less elegant MYOG lids.

At that same time, I've been thinking how the large cut-out in my cone (designed for feeding in wood) is negatively affecting efficiency because a lot of heat is escaping. The handles on my pot are positioned quite high, so no cut out is needed (unlike most pots).

I mulled over what would characteristics would define the perfect pot for me. I established these criteria:

1) You can get a ULC style cone for it
2) The largest (#2) Ruta Locura carbon fiber lid will fit
3) Pot handles are positioned high enough that you don't need a cut out

Only one pot meets these 3 criteria. It's the Evernew ECA278 750ml. Ideally I'd like to stay around 850-900ml, but 750ml is do-able and it'll save even more weight and pack smaller.

So bottom line is that I contacted Trail Designs and ordered this pot plus a custom cut down down. My cone is going to be perfect for the Starlyte stove, short enough to use the CF lid and have no cut out for max efficiency. That should be here in 2 weeks or so. My adventures with the 900ml pot have been great, but this is going to be the next level in light weight, efficiency and elegance.

The latest chapter in my adventures with ULC cones started today when a package from Trail Designs showed up.

I communicated with Rand and Russ at TD and got this custom ULC cone made from the 750ml Evernew pot as I described in my previous post.

This setup looks pretty normal in the pictures, but it's the details that make the difference. Notice the lack of a cut out for the pot handles, which means more efficiency. Also notice how the whole thing stores without using the lid space, so I was able to switch to the 7g carbon lid from Ruta Locura.

Going forward, I think I'm going to add a few holes to the bottom of this cone to boost up the air flow a little bit. It's a bit lower than my previous cone was, so the boil times are a bit slower. Hopefully I can get it dialled it without over-doing it.

Also, I'm looking to replace the stakes with a silicone band instead. The beauty of this is that the silicone band can permanently stay in place on the pot, so the number of pieces will effectively drop from 3 to 1. I think a silicone band is going to weigh 5-6g, so it should weigh about the same as the stakes.

Why not leave the pot support on the StarLyte and be rid of the stakes and band? Configure the cone to suite the StarLyte. The cone will prevent movement to the sides and give wind protection.

Dan – that's exactly what I've done with your Fancee Feest stove. I've cut down a cone to just the height needed to fit inside my Evernew Ultralight Ti pot (the wide 900ml version) and I'm using the pot support on the Fancee Feest stove to hold the pot. This has given me a nice compact light-weight cooking setup with a minimum of parts to lose. Everything fits inside the pot. So far it's working for me and, in side-by-side tests, I'm getting similar boil times and fuel efficiencies as my bulkier Caldera Cone and 12-10 stove setup.

Dan,

Why not get the TD Fissure and have a full cone that heats the entire pot?

I just got one for a .9L Deep Evernew and it all fits inside along with the inferno insert.

That also alleviates the need for the stakes.

I do like your setup. I have a ULC for an SP 700 I would like to do this with and love the starlight idea and being able to save your unused fuel.

"Why not leave the pot support on the StarLyte and be rid of the stakes and band?"
This was originally what I was going to do about 5 months ago, but Rand (from Trail Designs) explained this wouldn't be nearly as stable as using the stakes. He explained that when the weight is resting on the cone, the pot and cone essentially act as one stable piece. It can't tip unless the entire thing tips. Conversely, when the weight is resting on the stove, the cone doesn't add much stability because if the pot starts tipping, the cone can just slide with it and the pot can tip inside the cone or slide off the stove. Having the cone trying to keep the pot on the stove is better than a traditional windscreen, but still not nearly as stable as having the pot resting on the cone.

Rand's explanation is longer and makes more sense:
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=53228&skip_to_post=448765#448765

Also, then I couldn't use the amazing lid you sent me :)

Also, replacing the stakes with a silicone band seems like it's going to work extremely well. The silicone band weighs 6 grams, compared to 5 grams for the two stakes I was using.

"Why not get the TD Fissure and have a full cone that heats the entire pot?"
The Fissures are nice, but I believe this setup is lighter, simpler and arguably just as efficient.

With this cone, 450ml of the 750ml capacity sits inside the cone. Since I'm pretty much always boiling 500ml, there shouldn't be a significant difference in efficiency when boiling this volume. I've also got the bonus of no handle cutout, although you could do that with a Fissure as well.

In terms of weight, simplicity and ease of use, the ULC cone is superior…especially when using a silicone band instead of the stakes. There's just one dovetail enclosure to put together instead of two and you don't need to snap two cones together, so it's just as simple as the original Caldera Cone, but with the storage issue solved. The band always stays on the pot, so there's no hassle there. Super simple and easy, which has been one of my main goals.

I've ordered a skinnier black silicone band, which should be a little lighter and easier on the eyes than this one:

Yep – Have to admit that's pretty sweet.

Well – Thanks a lot … now you got me going down that road.

Did you ever find out what the plastic stove lid was from?

No. I got from it Dan/Zelph. Maybe he can tell us. I've been worried about losing mine and not being able to get another. A clear lid is easy to lose.

This is a cool project Dan! I may have missed it but what are the component weights of your current system? I love the simplicity of it.

LOL. Dan/Zelph probably regrets sending Dan that plastic lid! I imagine everyone is pestering him …. or at least I know I have. Sorry Dan. It's just good old fashioned "simple-smart".

Dan where did you get the silicone band? I've only seen them sized for beer cans (or is that what you have … just super stretched around your pot). Again the simple solutions wins, particularly where you can reduce the number of moving pieces.

Nice work. Like Craig, I am basically following your lead here and converting my system to same.

lol … me too about a month ago. I wanted to buy the stove with a lid but he did not have one he could part with yet.

I imagine he is trying to source them right now : )

Don't loose that lid Dan!

"What are the component weights of your current system?
Evernew 750ml Pot (ECA278) – 75.4g
Ruta Locura Carbon Fiber Lid #2 – 7.2g
Starlyte Stove w/o Pot Support – 12.4g
Cap for Starlyte Stove – 2.5g
Custom ULC Cone – 25.3g
MYOG Ti Stakes – 4.5g
Silicone Band – 5.8g

TOTAL: 127.3g or 128.6 with silicone band

For comparison, my 900ml Evernew Pot with the frying pan lid, 12-10 stove, standard ULC cone and regular stakes was 186.4g. So I've shaved off 49g and only 12 of those grams saved came from the pot switch.

"Where did you get the silicone band? I've only seen them sized for beer cans."
It's a wrist band, as opposed to a beer band. $0.99 shipped on eBay. This yellow one was a 'thick wristband' that I cut in half, but now I've ordered a regular width band since more width wasn't needed and yellow is hideous. You could probably even cut a regular one in half to pinch another 2-3 grams. Get em here:
http://www.ebay.com/itm/270704494233?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649#ht_3707wt_922

I sure hope it's silicone…it's supposed to be but I haven't tried it yet. I'll try it later today. I'm not sure how big the beer bands are. Maybe they're the same thing, but intuitively they seem smaller.

One neat thing with the silicone band strategy is that you can also vary the gap between the stove and the pot. So it's another variable to geek out over.

“Conversely, when the weight is resting on the stove, the cone doesn’t add much stability because if the pot starts tipping, the cone can just slide with it and the pot can tip inside the cone or slide off the stove. Having the cone trying to keep the pot on the stove is better than a traditional windscreen, but still not nearly as stable as having the pot resting on the cone”.

Dan, I think you gave up too soon. You should have tested the stability of the pot on the StarLyte while inside the cone. Having the cone right next to the pot will give it plenty of stability. I seriously doubt if you could tip it over any easier than having the pot rest on the cone. Rand talked you out of it. Now you have extra parts and that includes the lid. Once you’ve determined how much fuel to use, that amount will be consistant from one boil to the next. inside the cone. Measure your fuel (1/2oz) and there is no need to put a cover on the Stove, just let it burn out.

I’ve had a few ask where to get the lid. It comes with a can de-solder wick. 10 rolls of de-solder wick per can. Use one roll at a time and cover the remainder to prevent drying out of resin. I have not tried to source them out as of today. I’m playing with stove/pot assembly :-)

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I do still have the Starlyte pot support. I just slipped it back in to play with.

I can see a pretty good argument being made for using the Starlyte pot stand instead of the original Trail Designs stakes. It's a whole lot lighter (2g vs. 16g) and one could argue that it's sufficiently stable and quite a bit simpler. My MYOG 2g Ti stakes erase most of the weight difference, but the pot stand is still much simpler.

Compared to the silicone band though, I don't see an advantage gained by using the integrated pot support. The simplicity is the same since the band always stays on the pot, the weight is within a few grams (2g vs. 5g, maybe less) and without the pot support, the stove leaves more space inside my pot for other stuff.

Regarding the lid, using the silicone band (or stakes) gives me the option to use the lid or measure my fuel. So I'm not necessarily needing the lid. I could leave the lid at home and measure, but then I would need something to measure my fuel with, so I'd still have the same number of pieces. I could leave the measuring piece at home and use a fuel bottle with markings, but that's less accurate and I'd likely burn off more fuel than the lid weighs. So this decision comes down to simplicity (measurement marks) vs. lighter weight (lid). Using the silicone band lets me go either route.

If your cone is not completely round at the top your silicone band is going to melt and stink. My cone is not round and will allow a lot of heat to attack the silicone band. I have pliable measuring cups that I include with all stoves. I can send you a life supply at no charge. They are 1oz capacity graduated in oz and ml.

The cone right up against the pot while sitting on the StarLyte pot support will prevent the pot from spilling your precious water/dinner. The set-up I made with the Kmart grease pot and StarLyte stove could not be tipped over or spill the contents. The pot sides was 1/8 inch from the top of the cone teepee angular windscreen.

I'm the kinda guy who likes life to be as simple as can be. I like as few pieces as possible. No one really likes stoves that have to be primed in one way or another. The StarLyte is a champion when it comes to "user friendly" absolutely no priming necessary in cold weather. The burner that comes with the Caldera requires priming. I just recently tested mine, I know for a surety. Requires matches, not a bic type lighter to ignite it.

Thanks for the offer Dan. I actually have a few of those 1oz measuring cups around (they come with the TD cones), although I've never tried them. I should give them a chance. I've always assumed that fuel usage would vary quite a bit depending on water temperature and wind, so I've preferred to over fill, snuff and recover using the vacuum nozzle from Packafeather.

Once I get this cone dialed in, and I'm confident of how much fuel a pint will take then I'll try using the measuring cup. I'm having some awesome results right now.

Packafeather fuel sucker cap: http://packafeather.com/fuelbottle.html

Last night I spent way too much time playing with the variable of 'pot height'. The results are really interesting. I did multiple (2) tests at each height and averaged the results (although both tests were always very close because I've been diligent with controlling the conditions).

The stove is 0.8" tall, so the gap between the stove and pot (which is what I'm really playing with here) is 0.8" less than these absolute pot height figures.

Important: These tests were done with very cold water (40F), 500ml of water (6% more than a pint) and methanol fuel (less hot and energy dense than ethanol), so much better results would be achieved using ethanol and a pint of 60-70F water, which seems to be more of the norm.

We can see that fuel economy improves the lower the pot is inside the cone. Pretty straight forward, but good to confirm with actual tests. This makes sense because more of the pot in inside the warm cone, plus the stove is burning slower (due to having the pot really close) which improves fuel economy. Ultimately you could probably get the pot too close and mess up the combustion so much that it burns poorly and thus fuel use increases.

The boil time results are more interesting. We can see that if the pot is too low (ie. 1.4", or a 0.6" gap) then the stove is really getting stifled and a boil takes forever (~13 min) even if we do get great fuel economy. As you raise the pot up, the boil times get faster since the stove has more room to burn. This is true until you reach the point where performance diminishes because the stove is already burning as hot as it can, and the pot is just getting further away. The fastest boil times occur in the 2.0 – 2.3" pot height range (1.2 – 1.5" gap).

With those results, we can choose a pot height that strikes the right balance between speed and fuel efficiency. There's not much point in going lower than 1.8" (1" gap), because the fuel savings are tiny and the boils get a lot slower. In the context of my cone setup, 1.8" is a good height that's biased a bit more towards fuel economy. Going up to 2.0" shaves a full minute while increasing fuel use by 9%. This is a good option for people who don't mind burning an extra 1.5 grams in exchange for a minute saved. Any pot height that's higher than 2.0 isn't going to be much faster (eventually it gets slower) and it's going to burn a lot more fuel.

So the conclusion is that the reasonable range of pot heights is 1.8 – 2.0", with 1.8" being fuel economy oriented, 2.0" being speed oriented and 1.9" likely being a nice all around compromise with boil times in the 9 min range for this ice cold water.

For comparison, my original ULC cone with the wider 0.9L pot and the Trail Designs 12-10 stove averaged 16.5g of fuel with a 8.25 minute boil time in the same conditions. This is very close to the performance I'd get with a 1.9" pot height. At that height, my setup would probably do 16.4g with a 9 minute boil, which is a wee bit worse overall, but I think most of that is attributable to the narrower pot, which is fundamentally less efficient.

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Prior to all the testing last night, I did add 8 holes to the bottom of my cone with a hole punch, as I felt it needed a bit more flow. That had a big positive effect (30 second faster boils using nearly 2g less fuel) and I believe I've pretty much nailed the cone design now, so I doubt I'll make further modifications.

I also trimmed the silicone band is half (again) last night. It's still working great and now weighs just 2.5g. Awesome.

Going forward, I've got the cone design and pot height figured out, so most of the work is done. I'm going to play around with different amounts of water and different water temps to get a better understanding of how the performance will vary. As well, I'm going to get out in the field and do some tests in windier conditions and with cooler ambient air.

Hi Dan, pretty interesting.

I'm not too familiar with the stove you are using. Does it have a large single open chimney flame similar to the 12-10 stove?

Your results are interesting. Efficiency and time aside, for me the real interesting result is that the lower distance between the stove and pot bottom will allow for an overall smaller cone, which means that it will be easier to have a cone that fits inside your pot and possibly an overall lighter weight.

In my non-rigorous testing, initial water temperature is the parameter that seems to overall have the largest affect on time/efficiency for me. When I am out and about I will often try to pre-heat my meal water in my pack next to my back, or if I am camping next to a cold lake or stream, I will leave a pot full of water to "warm up" by itself on the bank.

> The cone right up against the pot while sitting on the StarLyte pot support will prevent the pot from spilling your precious water/dinner.

Not really…..the pot sitting on the pot stand is not connected to the cone. It can slide off the stand pushing the cone sideways. The most stable scenario is to have the pot sitting on the wide base of the cone….not some disconnected tiny base.

> Ultimately you could get the pot too close and fuel use would increase, because a boil would simply be taking so long that you're losing heat to the ambient air and past the peak of efficiency.

Actually….the issue of getting too close to the stove is that you can choke off the ability for the alcohol coming off the stove to fully burn….and that will be the source of the inefficiency…..alcohol goes away but doesn't provide heat. In fact, the slower you burn, the more efficient you make it. The most efficient stove we ever made didn't achieve boil until 37 minutes…..and used almost no alcohol to get there. Slow = efficient….almost always….unless you're in a blizzard.

Rand :-)

Dan, I'm interested in your improved draught through the cone. What is the total area of air holes you have now ?

Thanks for posting the component weights Dan. With your new half band the total drops to 125.3g (a 61g savings over your previous system). Pretty sweet!

"…for me the real interesting result is that the lower distance between the stove and pot bottom will allow for an overall smaller cone, which means that it will be easier to have a cone that fits inside your pot and possibly an overall lighter weight."

Yeah the possibilities this opens up was the main draw for me too. With this stove and the pot positioned 1.8 – 2.0" off the ground, you free up 1.0 to 1.2" of height (3.0" is standard height) which enables either more efficiency (cone comes up higher on the pot) or you can chop 1.2" off the cone and save weight plus be able to use ULC style cones in pots that were previously a bit short, or needed to use a fry pan lid to get the cone in there. With my first 0.9L pot, the cone went from about 30g to 20g when I chopped off 1.2 from the bottom.

"initial water temperature is the parameter that seems to overall have the largest affect on time/efficiency for me."
I'm not sure if it's quite this simple, but in my tests I've been going from 40F to 210F (boiling temp at 2000') which is a 170F degree rise. Starting with 70F water would drop that rise to 140F, which is only about 80% as much of a temp rise.

"…the issue of getting too close to the stove is that you can choke off the ability for the alcohol coming off the stove to fully burn"
Thanks Rand. It makes sense that it's more about ineffective combustion that losing heat to the ambient air. I wonder if you'd get higher carbon monoxide with the pot too low as well.