May 25, 2013 at 9:35 pm #1303400
So I took a crack at an alcohol stove like this: Skurka Stove and am having trouble getting it to work.
I light it, let it warm up for 30 seconds or so, set the pot on it and the flames are reduced to small blue dots in the holes, not reaching up to the pot. I lift the pot again, the flame comes back to life. Set it down, dwindles again.
Sounds like not enough oxygen – so is the solution more holes/bigger holes? I used an awl (don't have the hole punch) so I'm guessing that's the problem, but thought I would check with the collective wisdom here.
Thanks in advance.May 25, 2013 at 9:47 pm #1989782
What exactly are you using for fuel?
–B.G.–May 25, 2013 at 9:50 pm #1989783
I'm using Klean Strip denatured alcohol from the hardware store that says "for marine stoves" on the can.May 25, 2013 at 9:59 pm #1989784
If you refer to the Skurka web page photos and then look at your own, what appears to be different in appearance? As long as you have the right can and the right number of holes of the right size distributed the right way, then that is the first step.
Denatured alcohol ought to be right.
What are you using for a cook pot?
What are you using for a windscreen?
–B.G.–May 25, 2013 at 10:09 pm #1989785
Make the holes at least 1/4" diameterMay 26, 2013 at 10:36 am #1989884
@hhopeLocale: East Bay
It's not a 'skurka' stove, it's a 'Jim Wood' stove. Here's the real jim wood super cat stove page. It has lots of pictures and the full design and explanation, if you read that you won't make the error you made since Jim Wood explains it so thoroughly. I realize that skurka's self promotion is a useful way to make a living off of walking around outdoors, but getting this jim wood stove to be known as a 'skurka stove' is pushing it a little bit far.
These super cat stoves aren't particularly efficient by the way, and don't work well if at all on narrow pots, and without a base suffer from cold ground fairly significantly, and a base makes the whole thing too unwieldy, which takes us to the sgt rock ion stove.
I've been testing simple stoves and I'd say the sgt rock ion stove, made out of two 7.5 oz soft drink cans, with a pot stand, is probably the easiest and most efficient stove you can make. Here's the directions for making sgt rock's ion stove. With slx, that will give you reasonably consistent 17.5 ml boils of 2 cups at starting temp of around 70F close to sea level, if you follow his directions, particularly with the wind screen (1/4" free on side of pot, for 1/2" greater diameter screen than pot diameter) and pot stand height. Make sure to fully read the directions for either the sgt rock or jim wood stove and you will have a success right away no matter which method you chose.
You can make the pot stand out of wire or bike spokes instead, following the basic height / width dimensions of sgt rock's flat ti stand. 3 1/4 or 3.5" per side width is about right for the ion, 1 5/8" high about. You then bend the sides a bit to round the triangle so it fits around the stove, and inside the wind screen. You should add a pop can base (cut the top of the can off about where it starts to curve in, then pry off the tab, then bend back in the opening to make a sealed base) to the stove to both insulate the alcohol from ground chill and to keep the ground from burning, which adds about 3/8 to 1/2 in height to the stand. The stand should be about 5/8" above the top edge of the stove no matter what. The ion is easier to use, and does't waste any fuel on the priming phase since, all the heat from priming goes to the bottom of the pot.
Have fun. The jim wood was the first stove I tried making, easy, unless you make the base he shows you how to do, that's harder, worked fine after reading the jim wood how to, but it was not good for narrow pots and it's very inefficient so I looked elsewhere for a better design.
For simmering, true simmering, nothing comes remotely close that I have tested to a penny stove with a simmer ring added.May 26, 2013 at 11:30 am #1989901
Thanks for the replies.
To answer a couple earlier questions, I'm using an Anti Gravity Gear 3 cup pot, no windscreen while testing inside.
Looking at Jim's website (thanks for the correction on that) he mentions that steel takes a lot longer to prime than aluminum, and I think that's part of the problem – I'll probably start over with an aluminum can, and get a proper hole punch.
Thanks again.May 26, 2013 at 1:25 pm #1989927
@hhopeLocale: East Bay
you will gain an eye for cans of all types if you keep playing around with these stoves, heh. I believe jim wood lists the various types of cans that are aluminum, but you can make it easy by looking for the gold colored fancy feast cat food cans, you can tell if it's aluminum by tapping on the can once you get a feel for it too. Steel tends to also have a rolled joint on the bottom, while aluminum tends to be pressed. Not always, but usually.
For a heatshield ace hardware sells 6" flashing, maybe also 5", for almost nothing per foot. You can also buy a oven roasting pan then carefully cut the edges off and fold it flat then cut the screen out that. the flashing is strong enough to hold it's form when packed / rolled up inside the pot vertically, the stove pan isn't, but is foldable.
I believe jim wood recommends about a 1/2" gap in the screen, ie, diameter of screen is 1" larger than pot diameter. Measure pot diameter from the bottom of the pot, not the top, because the top has a lip that sticks out and doesn't count.
These require a fair amount of air, so you want air holes along half the wind / heat screen, so you can always face it opposite the wind. wind totally wipes out stove performance, which you will discover, but a good reasonably tall wind screen, and situating the stove out of the wind, helps a lot.
It's useful to pick up some 1oz medicine measuring cups, some pharmacies have them, so you know what it actually takes to boil the amount of water you want to boil per meal, that way you can bring a bit more than what you need but not too much more.
A heat reflector cut out of a pie tin or the rest of the stove pan, inserted under the stove, helps avoid forest fires, and also reflects heat back up to the pot, that's real threat. it's only a matter of time in my opinion before alcohol stoves are banned increasingly in summers in more and more parks due to the poor practices and designs out there.
Your pot is perfect for all stoves made I believe, just the right width. Do keep in mind with the jim wood super cat, if you knock the pot over, you knock the stove over too, that's personally why I prefer stoves with stands, but the super cat is a fine stove to start out with, but the efficiency is not very good. Jim wood to his credit states that he's not an engineer or designer, and doesn't pretend to have developed the best stove out there, just one that cooks pretty fast. Super cat is good for speed by the way, the ion is slower, which is one reason it's more efficient, that and a more efficient general design.May 26, 2013 at 1:40 pm #1989931
"no windscreen while testing inside"
A windscreen does more than simply shed the wind from the burner. It also helps channel the burner heat and keep it closer to your cook pot, and that also explains why you want an air space between the pot and the screen (at least a third or half inch).
The heat reflector that goes underneath the burner doesn't need to be much. I use a simple piece of aluminum foil. If you get too much going on under there, you might block off the intake air flow to the burner.
–B.G.–May 26, 2013 at 2:05 pm #1989938
@rosierabbitLocale: Pacific Northwest
I've used the AGG 3 C pot with a Jim Wood super cat stove for years with great success, even at 10,000' elevation and for winter backpacking. Thank you, Harald, for pointing out the stove's origins. I use the yellow bottle of HEET for fuel instead of denatured alcohol. Subjectively speaking, I think I get a more consistent output of energy. I recently bought one of Tinny's carbon felt strips to use as a windscreen. I also bought the 5" round carbon felt base to put under the stove. Light, wind proof, fire proof, and the windscreen then serves as a potholder. See https://www.minibulldesign.com/productcart/pc/viewPrd.asp?idproduct=110&idcategory=4
Sorry, I haven't taught myself how to use the clever quick link system yet, so just cut and paste the link.
I also made what I call a superdog stove using one of those blue dog food cans instead of the smaller Fancy Feast can. It's a bit bigger and more stable, but it needs an even wider pot.May 28, 2013 at 3:21 pm #1990499
@pda123Locale: Eastern Mass
The cat stove is a low pressure side burner category stove, and needs the alcohol in the stove to be hot (boiling) to produce sufficient alcohol vapor to push out of the side holes and ignite
Your main problem is that your pot of water is cold, and a good conductor, so when you place it on your stove, it sucks out all of the heat and stopds the alcohol boiling so there is insufficient vapour to push out through the holes. For the same reason, in cold weather you must have an insulator under the can to prevent the cold ground sucking the heat from the stove. A piece of carbon felt (plumber's mat) is ideal, but a circular piece of corrugated cardboard wrapped in aluminium foil is also pretty good. I find in really cold weather I need to "hover" the pot over the stove to take the chill off before placing it down in direct contact. Actually, I found a big improvement in simplicity of operation from an idea I saw on Hiram Cook's youtube channel. Make 2 wicks (strips of the aforementioned plumbenr's mat is a really good choice). They each go around half of the outside of the can and then each end is poked through one of the holes. The ends need to be long enough to go down to the base of the can. SO it looks like a wick completely around the outside circumference of the can, then the tails go inside, you may feel the need to amke a circle of steel wire tp jam inside the can to hold the ends of the wicks down on the base of the can. Obviously, if starting from scratch with a new can, only two 1/4 in (6 mm) holes need be punched on opposite sides of the can. As the wick is on the outside of the can, the can may still be used as the pot stand. Another advantage of this type is that the wicks are easier to light in cold weather. Also, one may place one's pot on the stove before lighting the wick, so no fuel is wasted.
Here is Hiram's video
I am currently experimenting with various can sizes and naterials to find the most effective combination of boil time and low fuel consumption. I have high hopes of a Vienna Sausage can with the wick 2.5 to 3 cm (1 to 1 1/4 in) below the rim. Time will tell.Jun 1, 2013 at 11:04 am #1992189
I had the same troubles so I modified my stove…
Ended up JB welding a tea light into the bottom and making a stand from hardware cloth.
Works well enough.
You must be logged in to reply to this topic.