Cat Can Stove - Questions

[donthaveoneyet]

Hi,

I'm working on lightening my pack. Have used a Trangia/Clikstand combo mostly, which I used to think was pretty light. I've been toying with the cat can stove, as in the one Skurka shows in his video where you punch holes in the can. It's pretty cool and the first one I made boiled 2 cups in under 6 minutes with a little over half an ounce of den alcohol. And it weighed a grand total of 0.20 ounces.

But I'm also moving toward a smaller pot, and the flames did lap up the side of the pot. So I thought maybe if I made the holes smaller, that might help. So I made one using a 1/8 inch drill bit in the drill press. Strangely, it took 9 minutes to do the same boil, and didn't seem to "bloom" as quickly. Maybe it was some other factor, not sure.

I also was wondering if the thing would work better with the holes lower on the can? I seem to recall with DYI Trangia stands, 1 inch was considered a good spacing between flame holes and bottom of pot. These are less than that.

So, for those of you who have some knowledge and experience with these, what do you think? Smaller holes better? Lower holes better? Or is the basic hole punch model like Skurka made the optimal approach? FWIW, in the pic below, the one on the left is the hole punched on.

Thanks!

IMG_0518[1].jpg

[Kookork]

If it boiled two cups of water under 6 min, then it is optimal. strangely, any minor adjustment in design of cat stove makes considerable difference in performance. If you make holes lower, then the volume of alcohol that it can hold is diminished and chances of alcohol splashing from the stove on the ground( or your hand ) in accidental sudden movement of the stove would be higher.

If you make the holes in one row( or make less than desirable holes) then the stove is prone to turn itself off when the wind is blowing fast.

[Odd Man Out]

Skurka's has recently posted an article on his blog about the deficiencies of the Super Cat stove. You might want to read that.

http://andrewskurka.com/2015/super-c...l-stove-flaws/

As you have seen there is usually a balance between efficiency (low fuel use) and power (low boil times). A few years ago a migrated away from super cat stoves for the reasons outlined in the blog post. You can increase power and efficiency if you go to a center burning stove. Currently I boil 2 cups of water in under 4 min with less than 15 ml of fuel. The stove only weighs a few grams but I rely on a relatively heavy 6.5 oz pot.

However if you want to experiment with cat food cans here are some tips I learned while still using them. one option is to build a pot stand that is slightly taller than the stove. Also build a windscreen that goes up the side of the pot and only slightly larger than the pot. Then try a stove with just one row of holes ( called a simmercat) and make an insulated base (foil over thin styrofoam). These mods accomplish several thongs. The base insulates the stove from the cold grpund. The fuel must boil in order to bloom. Suspending the pot a couple of mm above the stove on a pot stand has several advantages. A wide stand gives more stability to the pot. It makes the stove burn hotter so even with just one row of holes you get good power. The advantage of higher holes was already pointed out. The gap between the stove and pot allows you to put the pot on the stove immediately. It will burn slowly until it blooms but that fuel is not wasted as you are heating the pot during the priming period, thus increasing efficiency. I made my pot stands out of hardware cloth and my windscreens out of aluminum flashing. The windscreen helps promote a stable air flow and helps to trap heat as it rises up the side of the pot. The wind screen is not just to block wind. It is a necessary part of the whole system even when the air is calm.

[burger]

Why switch to a smaller pot? The supercat casts a wide flame, and it's really meant for a wider pot (note: wide does not necessarily equal big in volume. There are wide but shallow pots out there). The tiny weight savings from your smaller pot may cost you more in fuel weight and time.

[fastfoxengineering]

smaller diameter pot = zelph starlyte for the win

larger diameter pot = they all work pretty well imho

[capehiker]

Currently I boil 2 cups of water in under 4 min with less than 15 ml of fuel. The stove only weighs a few grams but I rely on a relatively heavy 6.5 oz pot.

That is a really good boil time. What stove are you using?

[atraildreamer]

...But I'm also moving toward a smaller pot, and the flames did lap up the side of the pot. So I thought maybe if I made the holes smaller, that might help. So I made one using a 1/8 inch drill bit in the drill press. Strangely, it took 9 minutes to do the same boil, and didn't seem to "bloom" as quickly. Maybe it was some other factor, not sure.

IMG_0518[1].jpg

I suspect the other factor are the notches you put in the top rim of the can pictured on the right in the picture. While the notching would help keep the pot from sticking to the stove, they would also act as a vent and not allow the burning fuel to develop the proper pressure for a good burn. Try making another stove omitting the notching and see what happens.

[Odd Man Out]

That is a really good boil time. What stove are you using?

The stove is an easy Capillary Hoop Stove (made form a small aluminum juice can). The pot is an Olicamp XTS which has a heat exchanger around the perimeter of the bottom. The wind screen doubles as the pot stand. It is a cylinder of aluminum flashing that is slightly smaller than the pot so it rests on the heat exchanger. There are air inlet holes around the perimeter of the bottom but no vents on the top. Thus all the heat is forced through the heat exchanger. The windscreen height is cut to store inside the pot. I use a piece foil as a base. I replaced the relatively heavy handle and lid that comes with the pot with lighter DIY handles (made of clothes hanger wire) and lid (made from a dimpled aluminum pizza pan - not shown). Also not shown is the snuffer, which is the bottom of a medium sized Red Bull can. With this I can put out the flame when the water boils and recover excess fuel. Without this feature you have to guess how much fuel you will need and either come up short (and refill mid-boil which is a safety hazard and tedious and time consuming) or your use too much fuel and have to burn off the excess (waste of fuel and huge decrease in effective field efficiency). It's very easy to use. Squirt in fuel, light, put on pot. I hold the stove in my hand to light. No priming. It will be going full speed by the time you get the pot in place. Snuff it out when done. The wind screen does not get very hot - if it does, your system is not very efficient.

pot2.jpg

[donthaveoneyet]

I suspect the other factor are the notches you put in the top rim of the can pictured on the right in the picture. While the notching would help keep the pot from sticking to the stove, they would also act as a vent and not allow the burning fuel to develop the proper pressure for a good burn. Try making another stove omitting the notching and see what happens.

Hm. That's interesting. I read somewhere (or maybe it was one of the gazillion useless youtube vids) that the notches would help. I'll try another one tonight (the cat is enjoy this process). Thanks.

[Odd Man Out]

I suspect the other factor are the notches you put in the top rim of the can pictured on the right in the picture. While the notching would help keep the pot from sticking to the stove, they would also act as a vent and not allow the burning fuel to develop the proper pressure for a good burn. Try making another stove omitting the notching and see what happens.

If you hold the pot 1 or 2 mm above the stove so there is a gap all the way around, the stove still pressurizes and the flame jets form normally. It actually increases the rate of the burn. I'm not sure why but it is easy to show. One way to do this is to get a heavy duty paper clip and made 3 or 4 U shaped pieces. Drape them over the edge of the stove so the pot rests on the clips, above the rim of the stove.

[atraildreamer]

Hm. That's interesting. I read somewhere (or maybe it was one of the gazillion useless youtube vids) that the notches would help. I'll try another one tonight (the cat is enjoy this process). Thanks.

I think that there may be another alcohol stove fanatic in the making!

Here is one of the possible results if you let the cat stove construction addiction get out of hand!

[Rocket Jones]

Someone here on WB, quite a while ago, did some testing using the SuperCat and wide vs. narrow pots. His conclusions were that the flames going up the sides were not as wasted as some believe. Wish I still had the link to that thread.

That said, I use a hybrid cat stove. Mine has the full top row of holes, and only half the lower row. It takes longer to boil, which is what I want because of the way I cook. When I did straight FBC, then speed was king, now I want the extra minute or two to heat and rehydrate my food.

I've always used a wind screen with my Super Cats, and thinking back on it, I've always used wide pots (KMart Grease Pot, then the GSI Kettle, and now a titanium pot with fry pan lid.

[donthaveoneyet]

Why switch to a smaller pot? The supercat casts a wide flame, and it's really meant for a wider pot (note: wide does not necessarily equal big in volume. There are wide but shallow pots out there). The tiny weight savings from your smaller pot may cost you more in fuel weight and time.

I should have been more clear. I'm not actually going with a "smaller" pot, but with a narrower one. I've been using a GSI kettle; it's a decent pot, but wide and short. I'm replacing it with a Toaks 1300, actually a bigger pot, but a little narrower and taller. Main reason is, I couldn't get stuff in the GSI that I wanted to carry in it (too short). The Toaks is also a little lighter. There's a couple of other things I didn't like about the GSI, although it works well with a Trangia/Clikstand setup. Haven't received the Toaks yet, but will re-run the tests once I get it.

[donthaveoneyet]

I think that there may be another alcohol stove fanatic in the making!

Here is one of the possible results if you let the cat stove construction addiction get out of hand!

Actually, I wish my cat would get that fat, then maybe she wouldn't spend every night chasing things around the house all night long... like tooth paste lids or pencils. Snakes and rats make much better pets (we have those, too). And dogs (ditto).

[burger]

I should have been more clear. I'm not actually going with a "smaller" pot, but with a narrower one. I've been using a GSI kettle; it's a decent pot, but wide and short. I'm replacing it with a Toaks 1300, actually a bigger pot, but a little narrower and taller. Main reason is, I couldn't get stuff in the GSI that I wanted to carry in it (too short). The Toaks is also a little lighter. There's a couple of other things I didn't like about the GSI, although it works well with a Trangia/Clikstand setup. Haven't received the Toaks yet, but will re-run the tests once I get it.

Just get an evernew 1300 mL pot. If you need to store more than your stove, windscreen, and utensil in your pot, then you probably need a bigger pack (or smaller everything else).

[donthaveoneyet]

Just get an evernew 1300 mL pot. If you need to store more than your stove, windscreen, and utensil in your pot, then you probably need a bigger pack (or smaller everything else).

The Evernew 1300 is only 3 inches tall. The thing I want to put in it (a Ziploc plastic container with lid) is 3.5 inches tall (and 1.40 oz) (homemade cozy adds a little to the weight and diameter). The Toaks 1300 is 3 7/8 inches tall (internal measurement - I like how Toaks gives very detailed specs, including internal measurements). The Evernew also doesn't have a bail, which I like. The Evernew is a little lighter, but when I take the handles off the Toaks it will probably be about the same. I have long stored my stove, windscreen, coffee cup, striker, matches and a small chamois cloth in my pot. For a weekend outing, I can also get my alcohol in there. With this, I expect to also get the Ziploc container and still come out a good bit lighter. That's the plan, anyway.

[burger]

Well, you seem determined to use the supercat with pot that is inadequate for it. But if you're really concerned about saving weight, I would ditch the plastic container and the cloth and just cook in the pot instead. I can clean any pot in under 2 minutes with maybe 1/8 cup of water and my finger without creating any waste. And if the pot is less then hygenic after I'm done wiping it out, anything growing on it will be killed the next time I boil water in it. Coffee cup? You already have a pot and/or a water bottle. Boom, you just saved about 4 ounces.

It seems weird to be worried about tenths of an ounce on your put but carry several ounces of unnecessary equipment.

[Odd Man Out]

I like the Olicamp pot because it has a 1 to 1 height to diameter ratio. This gives a minimum surface to volume rstio. So for a given volume this makes a pot with a lightweight and it will retain heat best. I don't think tall pots heat as well and the wide pots are not tall enough to stoe the rest of my cooking gear.

[donthaveoneyet]

Well, you seem determined to use the supercat with pot that is inadequate for it. But if you're really concerned about saving weight, I would ditch the plastic container and the cloth and just cook in the pot instead. I can clean any pot in under 2 minutes with maybe 1/8 cup of water and my finger without creating any waste. And if the pot is less then hygenic after I'm done wiping it out, anything growing on it will be killed the next time I boil water in it. Coffee cup? You already have a pot and/or a water bottle. Boom, you just saved about 4 ounces.

It seems weird to be worried about tenths of an ounce on your put but carry several ounces of unnecessary equipment.

I know. I can't argue with that. Just to be clear, I also sometimes carry an REI folding chair ("Flex Lite Chair", weighs about 1 1/2 lbs, older version). Up until recently, I used an external frame pack, and for years was a devoted fan of the Svea 123. And I wear big heavy leather hiking boots. It's hard to teach an old dog new tricks. But my approach nowadays is to try to save weight in areas where I can without compromising my "luxuries" too much. That means some "light" or "ultralight" stuff, and some not-so-light stuff. I don't claim to be consistent or logical, or even particularly smart.

My current cook kit is Trangia (3.95 oz), Clikstand (4.7 oz), GSI kettle (6.05 oz), and one of several cups, lightest being a GSI (1.85 oz). So about 16.5 oz, without eating/stirring utensil, starter, alcohol (all of which will net out, more or less). With the cat stove (0.20 oz), a homemade windscreen (less than .50 oz), the Ziploc bowl and lid (1.4 oz), the Toaks pot (5 oz) and the cup, I should be able to do the same basic things at about half that. That's 1/3 the weight of my chair. It may seem kind of pointless, but like I said, I don't claim to be otherwise. Oh, I forgot, the cloth weighs .30 oz, I just weighed it, but I will probably cut it in half.

I'm saving weight in other areas, as well.

But back to the point... so you think my choices in pots are not good for use with the cat can stove? Is it the width of the pot? The height? Not sure. A lot of people seem to like the MSR Titan, and it's not as wide as the Toaks. Or is it the overall volume of the pot? What would you recommend for a pot? And yeah, I may ditch the plastic bowl, but right now I'm liking how I can roll a freezer bag over the edge and eat out of it, or use it with a cold cereal and powdered milk mix.

Anyway, I appreciate your help and comments. And Odd Man Out, I forgot to thank you for that Skurka article. Very interesting.

[burger]

It's the width of the pot that matters because the supercat puts out a wide flame. I switched from a titan kettle to the Evernew 1300 (which is about as wide as ultralight pots get) and got much better boil times and better results. I vaguely recall seeing tests of different width pots with the supercat but I have no idea where I saw it.

That said, if you're happy with your system and don't mind slower boil times or using more fuel, stick with it. I'm just saying what I do and what I'd suggest if saving weight is paramount. Obviously, everyone has their own considerations.