Sep 19, 2007 at 2:39 am #1225111
Sooner or later anyone that hangs around BPL long enough is gonna make a stove !
My knowledge and pre-planning was very limited but here's how I went. It weighs about .75oz/25g.
For now I have only put in 8 small holes 1.2mm/1-16th of an inch) as I prefer a stove that simmers more than a blast furnace but it does not work too well.
So the advice I think I need is . . .
1: Do I stay with 8 holes but make them bigger
2: Go with more (16?) small holes
3: Try more bigger holes.
Photo 1. I started with a steel can that's 56mm x 36mm, 55g/2oz in volume. Cut out a hole in the top the same diameter (34mm) as the second component which is the base of a small aluminium aerosol can.
Photo 2. I used the base of the aluminium can as I think it will be structurally stronger so I drilled 3 small holes in the base, 8 holes around the top of the steel can.
Photo 3. The top is trimmed back to about 3mm/1-4th inch taller than the steel can.
Photo 4. The raised edge is 'rubbed' or 'rolled' to fit in/on/over the top of the steel can. I used the round nose of a pair of pliers to force and stretch the aluminium.
Photo 5.The fit is quite snug though not perfect.
Photo 6. You can see that the flame pattern is not too good. A lot of weak flame, I'd prefer some Ooph or a modest flame for simmering. It took awhile to kick in and get going.
Photo 7. A cross section of the stove.Sep 19, 2007 at 3:13 am #1402717
The problem with the flame pattern is that you have the holes pointed upwards. Drill the holes around the side about 1/4" down from the top.
Or buy an MBD Elite II and study it for a while.
CheersSep 19, 2007 at 3:16 am #1402718
Hi. I put them straight up like a Trangia does which is all I've ever used. I'll do as you say for version two (and onwards!).Sep 19, 2007 at 10:23 am #1402758
Hi Ian – You say that your knowledge and pre-planning was very limited. Did you follow instructions or did you create this by yourself? If you haven't already, I would go over to zenstoves.net and take a look at some of the different stove designs there.
I agree you should put holes on the side, this may give you more concentrated flames. But it will allow your stove to do double duty as a pot stand.
I'm not an expert, but I believe most pressurized alcohol stoves utilize many smaller holes, as opposed to fewer large holes. Lower pressure or non-pressurized stoves will use larger holes. (For example, compare the cat stove to the pepsi can stove.)
So, I think that if you make more small holes, your stove you will be able to create a more concentrated flame. You will have to experiment with the number and size to find the balance for the simmering requirement you mentioned.Sep 19, 2007 at 11:33 am #1402778
Ian, I like your design.
Rolled edge on the aluminum looks great. I like that concept for creating the walled chamber. You think like a Stovie
Steel containers will always take awhile longer than aluminum to get going. How does the time compare to your trangia?
Your flame pattern looks great. Once you put your pot over it the flame pattern will turn into one large mass of circular flame created by the pot.
How fast your fuel is consumed is determined by the amount of fuel vapor allowed to escape at any given time.
You want it to simmer, reduce size or quantity of holes.
Try boiling two cups with 1/2 ounce of fuel and see where you're at if you have'nt done so already.
Zelph's StoveWorks Newly created website, stop on bye, register, win a free stove in the "Mystery Tool" forum.Sep 19, 2007 at 2:20 pm #1402797
Nice job for a 1st try! Did you seal the top of the inner wall after you crimped it? Sometimes you'll have trouble getting the stove to light if you have a leak in the inner wall, or inner/outer wall junction. Also, since you went with a top hole design you might want to try a primer pan to light your stove. It should decrease your time to get the jets to light. How much fuel are you starting with. The more fuel in the stove, the longer to prime or boil the alcohol. Try starting with an ounce or a little less. It looks like the stove burns well after it has "blossomed".
The side burner design will provide you with 2 advantages: 1)the lower the jets are on the stove, the more the heat from the jets contributes to heating the stove body and vaporizing the alcohol, and 2)you can place your pot directly on the stove without the need for a pot stand.
Hope this helps.Sep 19, 2007 at 4:20 pm #1402808
Hi. Thanks for the tips.
This stove is my design based on my browsing around sites on the internet such as here and Zen Stoves. But I like the designing in the head process so I try and do my version even if it ain't right ! I need to find a recipe that I can use the peppercorns from the green can so I can justify buying more. I also need to ask my female friends if they use the girly spray stuff in the aluminium can so I can get their empties (!)
Suddenly I understand the advantages of smaller holes to create pressure, thanks.
I made a quick (and poorly made) version with holes in the side which looked promising.
I will do some comparing to the Trangia when I can.
I have not sealed between the steel and aluminium can which did not seem to be a problem but who knows, every litle bit helps and eliminating any minor escaping gas may be a good thing.
It actually lights easily and after a few goes I think the jets kick in in reasonable time.
When I made the side burner version, I sat the pot directly on top of it and it looked really good. But the flames died out through lack of oxygen. I'm still mystified as to how stoves work with the top totally blocked off either by the design of the stove or when the pot is on it. Maybe mine would keep going if there were a lot more holes, I don't understand this aspect of stove design.Sep 19, 2007 at 6:26 pm #1402820
Sounds like your side burner either needs more or larger holes, although I wouldn't rule out a leak somewhere on the inner wall. Need more details to tell. The way the side jet works is simply this: After the alcohol starts to boil and vaporize the gases expand between the inner and outer wall and out the jets, thus causing the jets to fire (that is why the inner wall seams being leak free is so crucial, leaky seals lead to stoves that won't stay lit or burn properly).After you place your pot on top the pressure increases slightly (to about 1-2 psi)thus increasing your flames. Lastly, the flames on the side of the stove warm the stove body, helping to continue heating the fuel and further aid in vaporization. That is why jet height placement as well as number and size are important. The lower on the body, the better heat to the stove (more critical in cooler weather), but the lower fuel capacity.Sometimes more heat and lower jets are not better, as it leads to the fuel expanding out of the jets in a raw state that causes the stove to "flare".
I would try sealing the inner wall with some sort of high temp epoxy like 600 degree JB Weld, or find a way to come up with a tight seal, and try that 1st. Then if your confident you don't have any seams leaking play with the jetting. Just my 2 cents.Sep 19, 2007 at 7:27 pm #1402834
Thanks George, you are making good sense to a novice like me.
I did have a lot of flaring and now I am certain I did have fuel coming out of the jets (and onto my bench!).
My inner wall is the base of an aluminium container so has no seams but I did drill 3 tiny holes in the bottom so fuel would transfer into the outer chamber. These seems the right thing to do (?).
I'll have a lot of fun doing some trial and error work and will probably acquire a taste for fancy french peppercorns !Sep 19, 2007 at 8:23 pm #1402848
Ian, great first attempt. You basically made a Trangia; cool! Pressurized side burners are the most complicated; they operate similar to the last three stages of a turbine engine, which my professors explained are "suck, squeeze, bang, blow". Those are not abbreviated instructions for a hot date, but rather the intake, compression, ignition, and exhaust stages, which occur continuously. Side burners can be closed off entirely because combustion occurs externally, after compression.
Its a fascinating hobby with very low overhead costs; soon I predict you will have a shoe box full of stoves; like many of us do..Sep 20, 2007 at 2:54 am #1402867
> When I made the side burner version, I sat the pot directly on top of it and it looked really good. But the flames died out through lack of oxygen. I'm still mystified as to how stoves work with the top totally blocked off either by the design of the stove or when the pot is on it.
You need to look at what is going on. Basically, the flames out the side mean the alcohol inside is boiling. You can't get big flames out the side unless the vapour inside is pressurised, and sitting the pot on top helps do that.
Now, you said the flames died when you put the pot on the top? One thing I can say is that there was no lack of oxygen for the flames, but there may have been a lack of fuel, or alcohol vapour. This has to mean the alcohol pressure inside dropped. This does actually happen quite often when people are learning how to use a pressurised side-jet stove. (Me too.)
Why might this happen? Because the pot was cold, and when you put that cold pot on the barely-warm stove you cooled the alcohol down too much, by conduction. The normal solution is to wait another 5 – 10 seconds before you put the pot on the stove: let the stove heat up a bit more.
Now, what about the internal sealing? It simply does not matter. The whole internal cavity is 'sealed' off by the pot. There are those little holes at the bottom anyhow, so sealing around the top achieves nothing.
cheersSep 20, 2007 at 4:39 am #1402871
Thanks guys. I've learnt a lot and may end up with shoebox full eventually! It may be some time but you'll see more threads here in the future by me as I keep experimenting and trying out new ideas.Sep 20, 2007 at 2:43 pm #1402947
>Now, what about the internal sealing? It simply does not matter. The whole internal cavity is 'sealed' off by the pot. There are those little holes at the bottom anyhow, so sealing around the top achieves nothing.
That's not entirely true Roger. The problem with not having a tight inner/outer wall seal is that it can create a situation where the jets will either 1) not light, or 2) light very weakly due to low pressure between the walls. You are correct in stating that it doesn't matter after the pot is in place, but it is important to get pressurization in the priming faze. I have witnessed this 1st hand, and was stumped until I realized the inner wall seam was leaking. Sealing around the top is more critical than down low, since your fuel will cover the bottom holes initially during the priming stage.Sep 20, 2007 at 4:22 pm #1402951
> The problem with not having a tight inner/outer wall seal is that it can create a situation where the jets will either 1) not light, or 2) light very weakly due to low pressure between the walls. You are correct in stating that it doesn't matter after the pot is in place, but it is important to get pressurization in the priming faze.
Well, fair enough too.
The little holes at the bottom will be under alcohol and so will hold a only a small amount of pressure, but that amount should be enough to push some vapour out the jet holes. I was assuming that the seal at the top was leaking only very slightly so the pressure inside would be largely maintained, but what I wrote was definitely misleading. Thanks for the correction.
CheersSep 20, 2007 at 4:53 pm #1402955
Roger, sorry if I came off wrong. The nice thing about the info here at BPL is that if you can sift through everything presented in any given thread you get usualy get some good stuff. In the end, hopefully this had been a help to you Ian.Sep 20, 2007 at 7:18 pm #1402967
> Roger, sorry if I came off wrong.
You did NOT come off wrong!
What I wrote WAS misleading: it's been many months since I used an alky and I had forgotten about priming. Your correction was valuable for the Forum channel. No use if you can't prime the stove! Equally, a stove is not much use if you use up as much fuel priming it as boiling the water – which has happened to me.Sep 21, 2007 at 2:44 am #1402994
Hey, guess what?
I already come up with a new design ! Ha ! That was gonna happen.
Your expert advice will be just as appreciated in a week or 3 when I start another " I've made a stove " thread !
I did manage to get the stove to keep working with the pot on it.Sep 21, 2007 at 2:24 pm #1403038
Can't wait Ian!
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