I recently purchased a Minibulldesign Nion2 (it is on the left in the picture below) and the jet configuration intrigued me.

I've built several dozen stoves and tinkered a bit with different designs but none of my modifications did anything particularly well.

Last night I decided to play with the jet configuration on a Penny stove. The hope was to produce a stove that would focus the heat for narrow pot/mugs. I find Penny stoves to be among the easiest to build so this would be the platform.


Penny stove plans are found here http://www.csun.edu/~mjurey/penny.html







This jet configuration really works well. The flames are focused and burn with a nice clean blue flame.

A 1/16th" bit was used to drill the jets.

I plan to build a couple more and wrap the bodies with fiberglass wick.

Edited by GSV45 on 12/09/2007 16:22:07 MST.

Greg,

Very nice flame pattern, and the rolling boil is good to see!

Nice job,
Todd

I think this picture shows the flame pattern better.

Nice mod. I'm always on the look out for a better stove/Heini pot combo.

How much fuel (and what kind) brought the 16oz to boil and how long did it take?

-Michael

In the picture above that is more like 20-21 ounces of water boiling.

I always use SLX Denatured Alcohol that you can buy at Home Depot.

I have not done a timed boil test. As you can gather from the pics my workbench is in my garage. Air temps have been in the low 30s in the garage so any timed result will suffer when compared to the folks testing their stoves indoors.

In a day or two I'll try to time it and post results. I suspect this version of the Penny burns a little cooler and longer but the stopwatch will tell.

Good Day,

I came across your tri-paired design at Mark's site. Excellent design for the Heineken pot :)

I also was having a hard time getting it to prime though, but I think I have the answer.

I built my base a bit taller, and cut out 3 sections of it, leaving small tabs to support the stove.

It only takes 5-6 drops of fuel in the base to heat the stove & it's off like a rocket!

The last test I did was with 1 3/4oz of Methanol and 2 cups of 70 degree water in the Heineken pot with a hardcloth stand. It boiled in 5:30 and kept on boiling for another 5 minutes. I am at 3440 feet BTW.

I still need to do some simmmer tests.

Rock on and thanks!

Hi Greg,
Nice Mod. I've made a couple of Penny stoves before and one thing I didn't like is the threat of losing the penny easily since it's a loose part. I thought of adding a nut rivet and thumbscrew to the filler hole (like Tinny does on the Nion) but haven't gotten arounf to it. Just wanted to throw that out there as an idea to improve the design.

Jason,

One of the coolest thing about the penny stove is that should be self priming and the loose penny is the regulator on the stove pressure. If you pour your alcohol into the top of the stove with the penny in place ideally it will just sit there with the penny sealing the hole. Light the fuel and as the air inside heats it will lift the penny slightly and fuel will run down into the main part of the stove. This will vaporize and start to jet. The original design jets out toward the raised sides of the stove and so the flame heats the stove and that heats the fuel etc. If the stove gets to hot the penny lifts and releases the pressure. It is truly ingenious.

Don't get me wrong, I'm sure the rivet/thumbscrew would work, maybe even better, but I just kind of like the idea of the penny regulator. Like you I worry about the loss of the penny so I carry a couple extra pennies when I use mine.

-Mark

on the normal penny, with the jets on the outside, I have NO problems getting it to prime!

It's only when you move the jets inside that it gets tricky. probably because I'm just getting into this... ;)

boba,

I made a inner 3 jet penny stove last year and had the same trouble until I figured out that I needed some way to keep the stove body hot. My rough and inelegant solution was to make the sides higher and then bend them over so that part of the side was in the flame of each jet. This works well, but looks terrible. One could probably make 3 tabs on the sides, like on your primer pan, and bend those over for a cleaner look.

-Mark

Hey Mark,
I see your point about regulation but that raises 2 questions for me:

1. If there is the possibility of "overpressurization" of a stove, doesn't that mean that the design is flawed somehow and that it could be mitigated by altering the jet pattern?

2. Priming a stove from the top is a waste of fuel. Priming from the bottom (or at least the sides) is much more efficient. So, wouldn't it be better to use a priming pan or bonded wick?

Let me know your thoughts.

bending the top in makes sense - does that make the flames higher once it's lit as well because the stove is hotter?

thanks,
jared

Jason,
Sorry about being so late in answering, but I was out of email contact ("gasp") for the last few days.

1. Over-pressurization: Well you have a point, but I like to think of the penny as a constant pressure device- Like the regulator on compressed air tanks. The penny makes up for the vagaries of fabrication and the imprecision of construction, differences in fuel quality, etc. Kind of a built in fudge factor that make it a very forgiving stove to build and operate.

2. Priming: You are right about the inefficiencies of priming from the top, but I would offer that it is not a "waste of fuel." When you pour the fuel in the top you can set the pot on the stand and light the stove. The heat of the prime is immediately heating the stove AND the pot. So the penny stove is working like a tealight stove at that point. As the stove warms it morphs into a pressurized jet stove. I could argue that "priming from the bottom" is the waste of fuel, as less of that heat would be available to the pot. Side heat would be a little better. But top, bottom, side- it is probably not much of a difference.

More important to me is the "fiddle factor." - place the penny, fuel, light- is simple verses -unscrew the thumb screw, fuel, replace the thumbscrew, poor fuel in the primer pan or on the wick and then light-. Ok not a big difference, but hey I'm trying to make a point here :-)

Now, I have a MBD Mini Sith that I have used in the past and it is a great stove, but over time I found the thumbscrew thing a nuisance for me.

Cheers,
-Mark

Edited by markhurd on 02/18/2008 11:18:31 MST.

Jared,

Sorry about the delay in answering, Just got back from a trip.

You're right the stove tends to burn faster with higher flame. You can tune this somewhat by bend the sides in more to heat the stove/fuel a little more or bending them away to heat the stove/fuel a little less.

-Mark

I dig the primer-pan/base. I'll have to try it.

Like Jason suggests I have wrapped fiberglass wick around 4 of these Narrow Pot Penny stoves. This works fine for priming. You have to be careful to avoid overpriming with the wick.

I also thought about drilling a hole in a penny and putting a thumbscrew through it to transfer more heat to the alcohol in the stove body. (Tinny does this with the Nion 2) My use of the stove this winter has convinced me that it isn't needed.

In my experience this stove burns on the cool side UNTIL you put a pot on top of it and wrap it with a windscreen. My guess is the concentrated/merged flames creates a "hot zone" that is enough to efficiently drive the vaporization.

If you wanted to try the thumbscrew idea I think it would be a good idea to flatten the convex portion of the bottom can.

Right now I really don't relish the thought of choking down more nasty Heineken (I like dark beer/ale/stout/porters) so I'll let you guys do the tinkering for a while. :)

When building conventional Penny stoves I found those built entirely from Heinie cans slightly outperformed those built with Heinie bottoms and different cans for the top.

For this round of tinkering I stuck to the Heinie cans for top and bottom but I've noticed the stamped numbers on the cans seem more pronounced. The penny does not seal as well with these numbers so I ended up filling the stove body with fuel and then putting a penny or a nickle over the fill hole before lighting.

MAYBE these stoves would operate in the classic manner that Mark describes (tealight --> pressurized) if you used cans without the stamped numbers. A priming system might not be needed with smoother cans....

some videos here:

http://picasaweb.google.com/hiflyer.x/AllThingsPennyStove

rock on!

Edited by hiflyer on 02/24/2008 19:06:05 MST.

Greg,

I sand or Dremel those pesky numbers off for a good seal and better jetting. Bigger coin can also work.

Jared,

Nice videos!

-Mark

Edited by markhurd on 02/24/2008 19:42:54 MST.

This is my lunch today (Thai curry noodle soup.)from my snowshoeing outing. 13 degrees and very windy at 8500 feet. (You can see the wind pushing the steam away)

The stove is the (unnamed) one we've been discussing. The windscreen is made from recycled foil roasting pans.

Somebody think of a cool name!

I had to drop some snow into the boiling soup to calm it down a bit. The noodles cook better at a slower pace. I'll confess to never using the simmer rings. I'll have to try them sometime.

Hi guys, I'm new here, but I wanted to ask what you are using for a pot stand for your penny stove. I have been experimenting with the penny stove quite a bit and like it alot!