Modifying a Trail Designs 12-10 alcohol stove ?

[Dean F.]

I'm puttering about with my Christmas present- a Ti Sidewinder for an Evernew 0.9L pot. On the TD website they say that the 12-10 stove won't fit in this pot with the Sidewinder and they include a Tupperware widget to store the stove in your pack, but fiddling around a bit it seems quite clear that the stove WOULD easily fit if the integral priming pan were trimmed off.

The instructions for the 12-10 stove implies that the priming pan is only really needed in cold weather. Personally, I find it desirable that my cooking set be as compact as possible.

So- and if Rand is skulking around here I'm particularly interested in his opinion- is there a big downside to trimming off the priming pan? I have another 12-10 stove that I could preserve for cold-weather use. For that matter, does TD make a priming-pan-less 12-10 stove? (I know that they don't- hint, hint.)

Has anyone tried this? Conceptually at least it seems obvious that there wouldn't be any issues for warmer-weather use.

[Bob Gross]

If you don't like the size of the normal priming pan, then you can use a collapsible priming pan. Just put a piece of aluminum foil there and burn the priming alcohol. Afterward, you can fold up the foil and stash it anywhere. There is nothing very critical about the pan, just as you can burn some alcohol there to produce bottom heat.

–B.G.–

[Dean F.]

True…

I'm really not seeing a down side to this. But I know that Rand spent a LOT of time and effort optimizing his stove for the Caldera system. I just want to be sure I'm not shooting myself in the foot on efficiency or anything by not priming.

[Bob Gross]

"I'm not shooting myself in the foot"

We will try to uphold your Second Amendment rights. Or, is that a cliche?

I hate cliches like the plague.

–B.G.–

[Franco Darioli]

yes, cliches are a dime a dozen.

Never used that priming pan myself.
In cold weather I use a bit of Vaseline impregnated cotton to get it going.
The al foil Bob is suggesting could also be used as a snuffer and recovery cup so that you end up using the minimum amount of fuel needed for the job

[Dan @ Durston Gear]

I've being using a 12-10 stove for years and I've never used the priming pan. If you can remove it while preserving normal functionality then I'd say go for it.

Or better yet, if your 0.9L pot is the wide shape then ditch the 12-10 stove and the stakes to hold in place. Just set the pot directly on the cone via it's rim, and replace the 12-10 stove with Zelph's Starlyte stove. There's many advantages to this including compactness, winter lighting ease, weight, simplicity….

See this thread – mostly pages 3-4.
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=57721

[Ken Thompson]

I've never used that priming pan either. My guess that the real reason it is there is to make things just a bit more stable. Cut it off, it is a can, not an arm.

[Bob Gross]

My previous understanding was that expending 3ml of priming alcohol will _warm_ up the main alcohol load. Then, when you ignite the main load that is already warm, you get a slightly faster boil. The alternative is to add the 3ml of alcohol directly into the main load and ignite it directly without priming. I think you get about the same overall fuel efficiency either way, but you might get quicker speed by priming.

–B.G.–

[Greg Mihalik]

I've removed the priming pans from all of my 12-10s. They pack better for me that way.
In cold weather I fill the stove and then I fill the top rim with alcohol. Easier to light. It works.

I use a Dremmel with a carbide bit, because of it's cutting pattern not hardness, to trim most of the pan. I get things close and then finish up with a file.

The outer can is minimally bonded to the pan. If your "cutting frequency" makes everything flop around you may break that bond. (Hence my preference for a fast cutter and a slow file.) If that happens re-bond it with something like JB Weld.

[Rand Lindsly]

There's no issue removing the outer rim of the primer pan to get it to fit into a 900ml Evernew with the Sidewinder. The only thing you need to be aware of is that the primer pan is holding the two stove walls/cans together…..so as noted…..you will want to use something like a dremmel or tin snips etc to remove the outer pan rim…..but leave all the stuff underneath so it holds it all together.

Rand :-)

[Dean F.]

Thanks, Rand!

@Dan "Just set the pot directly on the cone via it's rim, and replace the 12-10 stove with Zelph's Starlyte stove."

Well, how wide is the Starlyte? Will it fit in the 0.9L Evernew pot sideways? (In your setup it just sits flat in the bottom of the pot.) Does Zelph still have plastic caps for the Starlyte? Are they leak-proof, if I have the stove sideways, or upside-down?

[William Chilton]

The Starlyte fits sideways in the 0.6L Evernew wide pot, so there should be no problem with the 0.9. Zelph had the lid a few weeks ago, and it is still on the website, so I would guess it's still available. I haven't used mine yet so I can't comment on how leak-proof it is.

[Dean F.]

OK, why not? The simplicity of possibly being able to forgo the two tent stakes appeals to me, too. I just ordered a Starlyte, and I'll let you all know how the experimentation goes. If it goes poorly I'll be butchering a 12-10.

[Dan @ Durston Gear]

"Will it fit in the 0.9L Evernew pot sideways?"
The Starlyte is quite a bit smaller than the 12-10, so it should easily fit. The Starlyte is 2" in diameter.

"Are [the caps] leak-proof, if I have the stove sideways, or upside-down?"
The stove itself is leak proof because the wicking material absorbs the fuel and does not drip even if inverted. The function of the cap is primarily to stop evaporation, as alcohol is volatile and evaporates quickly.

"I just ordered a Starlyte, and I'll let you all know how the experimentation goes."
As the graphs on page 3 of my other thread show, pot height is an important variable. With the Starlyte you want the pot held pretty close to 1.8-1.9" off the ground. If you go higher then fuel usage goes up, and if you go lower then boils get slow. I believe with your 0.9L pot and Sidewinder cone, the pot is going to rest about 2.0 – 2.2" off the ground when supported by it's rim. You can simulate a 1.8" pot height (1.0" gap between stove and pot) by putting a small spacer under the stove. If you're happy with those results you can commit and trim ~0.3" off the bottom of the cone (hey more grams saved, and it packs even easier).

The other important variable is oxygen availability. In a normal cone the Starlyte burns a bit slow due to the low oxygen availability, which the 12-10 is optimized for. I added a few extra holes around the bottom of my cone (shown in other thread) for ideal performance. You can simulate this by creating an air gap around the bottom of the cone by placing the whole thing on a few spacers (ie. lay down some tent stakes and set the cone on that) while still remembering to adjust pot height accordingly. If performance is better with an air gap around the bottom, then it needs a few more holes to burn ideally.

You don't want to overdo it on the air holes though, because in the real world (ie. some wind) more air seems to get through the holes, so an ideal burn in the lab could burn lean in the woods.

[Dean F.]

@ Dan

Ah, thanks. That picture tells the story I was looking for. I also have a small fuel bottle that should fit inside the pot, too, for even more pack volume savings- it is flat like a hip flask rather than round like the one Rand provides. It's small, though, so only good for weekenders.

One issue with trimming the cone is that it might futz up the use of the Inferno insert. It seems pretty specifically sized to the cone. At the least the Inferno may require trimming as well to get it to fit. Perhaps a spacer under the Startlyte will be the best answer. Or, hell, maybe just biting the bullet and trimming the priming pan off the 12-10 will be the best answer. At least if I futz that up it's cheaper to buy a new 12-10 than a new Ti cone…

But I'll play around with the Starlyte first, and let the Hive Mind know my results.

[Russ Maynard]

I don't know if this helps, but I have used a MBD Mini atomic with good success. I got the idea off of hammock forums.

[Dan @ Durston Gear]

I've actually got a Mini Atomic coming my way in the mail right now. The Starlyte has a unique list of attributes that few other stoves can equal, so I don't anticipate the mini Atomic replacing my Starlyte, but I am interested to see how cleanly a self pressurizing stove like the mini Atomic can burn butanol, which I have coming in the mail too.

[Dean F.]

Update-

I just took some measurements and the unmodified Sidewinder holds the bottom of the 0.9L Evernew pot 2+5/16 inches off the ground if supported from the pot lip rather than using the tent stakes. So I'm guessing that, yes, I'll either need to shim the Starlyte upwards by 7/16 inch or so, trim a similar length from the cone, or use the butchered 12-10.

@Dan- At what elevation were you doing your experiments with the Starlyte? I live at almost 7000 feet, and that's usually the lowest point of my hikes.

But also, yes, with the priming lip trimmed off the 12-10 fits inside an Evernew 0.9L pot with the Sidewinder:

You an also see my "weekend" hip-flask-shaped fuel bottle. The mini-Bic and measuring cup are inside the sleeve with the Sidewinder, and the entire Inferno system is included.

Having just done a test-run, I remain impressed as hell with the cone and 12-10 system.

I also spent a half-hour or so snipping and sanding the sharp bits from the edge of the Inferno grate. Because I'm like that.

Oh, and putting a few drops of alcohol in the crimp on the top of the 12-10 makes it much easier to light, as mentioned above somewhere I think, and would probably work just fine as a priming device in itself. I think this is a good, quick solution. But I'll still play with the Starlyte- it does look interesting. Hell, I'm even thinking of commissioning a custom cone from Rand that's 7/16" shorter and with only the woodburning holes for the tent stakes so that I can still keep the original cone as-is…

Therein lies madness- this stove stuff can consume one, y'know?

But the shorter cone would fit even more easily in the pot and I could do away with the need for the tent stakes except in woodburning mode. For 90% of my hiking the woodburning option is really only for emergencies, anyway, so I think that I can do without the Inferno insert most of the time, too. I'll have to ask Rand what he's asking for custom cones these days, but only after I get the Starlight and verify what height I need with some experimentation. Maybe I'll even try to find a controllable location at around 9000 feet in which to experiment…

[Drop Bear]

Here are some instructions by Don Meredith from his lightpack blog ,

After reducing the priming pan on the 12-10 I can fit it into the Evernew Titanium Ultra Light 600ml Pot (ECA251) with the inferno and floor.

*edited to get the link working

[Dan @ Durston Gear]

Virtually all my Starlyte testing was done at 2000'.

[Dean F.]

Well, I had a package from Zelph waiting for me when I got home from work today. I had ordered a Starlyte with a lid, and I have to wonder if he was reading this thread because he sent it without the pot stand. But he also included a second Starlyte WITH a potstand, and one of his windscreens, and a little disposable aluminum foil ashtray that I suspect is meant to be used as a priming pan but which suspiciously also makes a great 3/8" shim for the Starlyte… Hmm…

Anyway, thanks Zelph.

So I did some preliminary comparisons with the 12-10. I ran boil times on 600mL of 55F tapwater. It turns out that my wife just bought a nifty new digital meat thermometer that includes both a timer and an alarm when a set temperature is reached. Mwah-hah-hah!

Hey- she stole my digital scale, so payback is a bitch.

Anyway, I set the thermometer alarm to 200F. My house is at almost 7000 feet and it is worth noting that the water was in a rolling boil by the time the thermometer read 200F. I'm not sure if that jives with the altitude or if it is merely some systemic error, perhaps because the remote thermometer probe wasn't fully immersed (I didn't want it touching the bottom of the pot). Thus these results may be a bit premature, but I figured I'd give some rough first impressions.

Unfortunately I got some pretty wide variations on repeat runs. In retrospect I think I found the error- I was eyeballing 600mL by the graduation on my pot, which is clearly inaccurate. I should have used a measuring cup (not having a graduated cylinder handy). Nonetheless some things are clear:

I ran the 12-10 using the tentstakes as intended. It is worth noting that one stake got red-hot and deformed under the weight of the pot- these are the included titanium stakes. I then ran the Starlyte with the pot resting on the lip of the cone, without the stakes. As expected the boil times and fuel consumption on the latter sucked- they were both significantly worse than the 12-10.

Then I shimmed the cone and Starlyte up to allow better ventilation and run it a bit more lean (i.e. allow more air/oxygen in):

Doing this resulted in boil times and fuel consumption both quite significantly BETTER than the 12-10. Clearly, yes, the Starlyte needs to run more lean, as Dan had found.

I then used the ashtray to shim the Starlyte up by 3/8", which should have put it in the "sweet spot" regarding height to the pot from Dan's experiments. However, I got very similar times and fuel consumption to the previous results.

But as I mentioned I think I have identified the source of my result variability. When I get more free time (probably not until at least this weekend) I'll repeat some runs with better water volume measurements.

I know that Rand did extreme amounts of testing when developing the 12-10 to get it to perform well in the widest possible conditions- I remember it. And, having used the 12-10 in Caldera Cones quite a lot in varied conditions I have to say that they impress me, but in purposely making a generalist stove the 12-10 probably truly EXCELS nowhere. I'm thinking thus that 7000 feet may be one place where the 12-10 performs well but doesn't excel, and perhaps this altitude is the Starlyte's prime time.

Another question, of course, is "Does the 12-10 need to run more lean at this altitude, too?" I would seem to make sense that it might but I didn't test that. (But I will.)

Also, as advertised, the Starlyte is very easy to light and is spill-proof.

Anyway, more will follow.

[Dan @ Durston Gear]

Great to hear things are coming along. Stove testing sure is fun. Nice to see you're getting some interesting results.

[Dean F.]

So, I measured 2 cups of water very carefully, and did two trials for each data point and averaged them- all were consistent. I called water "boiling" when the temperature rose by 120F (because that gave me target temperatures around 180F, at which point bubbles were continually breaking the surface, but not a rolling boil). I did not use a lid on my pot, since it seemed to shift around, so I removed it from the equation. My pot is an Evernew wide 0.9L. My house is at almost 7000'.

On the charts below you see a line for the Starlyte stove with varying numbers of shims under them. 0 shims means that I shimmed the cone up to allow better ventilation, but also shimmed the stove up to keep it at "ground level" relative to the cone. -1 shims means that I did NOT shim the stove up, so it actually sat a little lower than the bottom of the cone. Each positive numbered shim is one layer of cardboard used to shim the Starlyte higher and higher, closer to the pot (4 shims is about 7/16"). 4 shims should have the stove well into the "sweet spot" that Dan derived.

So, as the x-axis moves to the right, the stove gets closer to the bottom of the pot.

You also see two single-data points; both represent the TD 12-10 stove. One is with the stove used as directed with tent stakes holding the pot high, and the other is with no stakes and thus with the pot supported on its lip (i.e. closer to the stove).

Fuel Useage:

Boil Times:

You can see that I got much different results than Dan. I don't know if this is due to the altitude or what.

The 12-10 stove used as directed (with the stakes holding the pot higher)has the best fuel consumption, and the worst boil time.

The Starlyte curve shows better boil times the FURTHER the pot is above the stove- unlike Dan's data. Altitude?

If I use the 12-10 after removing the stakes and let the pot sit on it's lip, as with a Classic Caldera Cone, it looks like fuel consumption may be similar to the Starlyte, and boil times improve significantly but are still inferior to the Starlyte.

(Just for grins, I also checked the 12-10 with the cone shimmed up for better ventilation and there was no significant difference in either boil times or fuel consumption.)

Some thoughts:

1) Really, the difference in fuel consumption across this range is very trivial, 0.34-0.41 oz. Even if we double that to allow for a higher volume of really cold water taken to a true rolling boil, we're talking 0.68-0.82 oz, a 0.14 oz range. It would take 3.5 days with two boils a day to cost you one measley ounce. Or, thinking of it another way, the difference costs you about 3 ounces over a 10-day trip. So, I think that other factors might be considered more important- burn time, packability, stove weight, etc. On these points (under my conditions) the Starlyte seems to win- it's faster and smaller, and weighs about the same as a 12-10, plus has the anti-spill capabilities.

2) I'm willing to bet that some data got scrambled on that fuel consumption curve for the Starlyte. I suspect that this function is somehow dependent on my starting and ending water temperatures, which varied from 51-172F to 64-184F. In theory it shouldn't be, but I'm trying to think of reasons to explain that double-hump. Well, really, I need to do about 20 trials at each data point to be rigorous, but that might be bordering on OCD. Anyway, I'll bet that in reality there is just an improvement in fuel consumption as boil time increases (within reasonable limits).

3) In general, given my conditions and pot choice, the Starlyte trades faster boiling times for higher fuel consumption, though lowering the pot onto the cone lips with the 12-10 stove lessens this effect.

4) With the 12-10 stove I can speed my boil times by about 1.5 minutes at the expense of 0.06 oz more fuel consumed, merely by not using the tent stakes to support the pot. That sounds like a reasonable trade. (Though for about the same fuel use, the Starlyte boils considerably faster. It just requires more ventilation.)

5) Since I'd have to punch more ventilation holes in my cone to use the Starlyte efficiently, I think I'm sticking with the 12-10 for now. The differences really aren't that large, and an 9 to 11 minute boil time doesn't annoy me. I may toy with the idea of a custom cone for the Starlyte when the fanaticism bug hits me again.

[Dan @ Durston Gear]

Interesting results. I think one significant difference between our setups is that my pot is tall/narrow, whereas yours is wide. So for a given pot height, you've got a lot more volume of air under the pot inside the cone. The larger cone circumference may affect airflow etc.

Upon initial glance, your graph of pot height vs. speed looks roughly similar to mine. My X axis is pot height, whereas yours is # of shims, so our graphs are flipped on the x-axis compared to each other. (ie. As you go to the right your pot height is getting lower, whereas mine was getting taller). Your -1 and 0 shim tests are the fastest ones, with seems to correlate with my observation that ~2.3" is the fastest. And then we both observe boil times taking longer as the stove is raised up, so the sweet spot seems to raise the stove up just enough to get good fuel economy.

You're fuel economy graph seems a bit funky. I wonder if maybe you happened to get a little better than normal fuel economy at 2 shims. Changing the .37oz to .39oz gives a nice graph. One interesting take away from your tests is how the fuel economy seems to vary less than mine does. I suspect this is because your wider/larger volume cone is less sensitive to height tweaks. I seem to have observed about a 20% spread in fuel economy over 1.5" – 2.3" pot height, whereas your data seems to fall within 10% or so.

Since you're fuel economy varies so little, I'd probably opt for a setup equivalent to about 1 or 2 shims.

[Dean F.]

Yeah, clearly something is awry with that fuel consumption graph at 2 shims. I'm pretty confident that it should be smoothed, as you describe. Perhaps some day I'll get around to repeating it.

Regarding the rest:

Do you really think that the wider pot makes that much of a difference? Your "sweet spot" regarding pot height is around 4 of my shims- just when my boil times start to go to hell. My "sweet spot" seems to be with the pot suspended much further from the Starlyte.

I guess I can see how the wider pot might mean less variance in fuel consumption- as long as the flame isn't wrapping around the pot sides and going "out the chimney", I guess there would be less variance because most of the heat is washing around the pot bottom anyway.

Hmm… So, yes, I guess I see how a wider pot might be more tolerant of minor changes like this.

When I try to figure out how much extra venting I need by multiplying the circumference of the cone bottom by how high I shimmed it up I get really large numbers- almost 3 sq in. That's a lot of extra TD vent holes.

And, yes, I have considered ordering a custom cone that's 0.22" shorter and with twice as many vent holes…

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