Caldera cone metal

Piper, check out 2Question's Youtube video on how to make a Caldera Cone.

It is a good quality aluminum alloy. You might find aluminum flashing (roofing and siding materials) in a hardware store, which is typically softer stuff. Aluminum comes in many alloys and varies in hardness, flexibility, etc. I have re-purposed some aluminum duct material with decent results.

The Caldera cone is a very precise cut. The coupling for the side is a dovetail sort of arrangement that is a precise fit and the top is cut just right for the pot. In other words, it is harder to make than you might think. I thought it was expensive until I had one in my hands. They earn their keep!

Check out zenstoves.net for instructions and templates to make a cone-style pot stand (among others):
http://zenstoves.net/PotStands.htm#Cone

If you go to your local library you can probably find a vocational instruction book on sheet-metal bending and cutting. Have fun and watch your fingers– the cut metal can be very sharp. You can sandpaper the finished edges to dull them or I use a knife sharpening stone to un-sharpen them.

Diane, once you get the aluminum Caldera mastered, you can move up to the titanium version.

Seriously, that would be step up, because titanium is difficult to work on. After all of that trouble, you could burn wood in it. Whereas, the aluminum one would deform from that much heat.

–B.G.–

Time to go to Ikea and get a DIY wood stove for a few dollars!

The thing about wood stoves that I just don't get is why not leave the stove home and just place your pot right on top of a tiny fire?

So "aluminum flashing" is the name of the material?

Maybe if it's really super hard to do I shouldn't try. But then again, I have learned how to make shoes so maybe I can learn how to make one of these.

Maybe you can trade your skills with shoes etc. for a cone ? Nothing like division of labor.

Dianne, it is not hard at all. I have made three. Aluminum flashing cuts easily with household scissors. If you viewed 2Questions video he simplifies the pattern making process. It is about an hour project.

Piper, you can put your pot directly on a tiny fire. However, in many areas of California in the summertime, open wood campfires are not allowed. In some areas, they classify a Caldera stove as a camp stove, not as a campfire, since it is enclosed. Open wood campfires are kind of bad if it is windy. That is the beauty of the titanium Caldera, because you can burn wood, or alcohol, or Esbit. With the aluminum Caldera that you propose, you can burn alcohol or Esbit.

If you put a sheet of aluminum underneath the Caldera, you should be able to eliminate any trace of your fire after you leave.

Get the design pattern and study that before you start.

Aluminum flashing metal comes in rolls of various widths, lengths, and thicknesses. Start with a Home Depot and work your way out.

I doubt that you will find it to be super hard. Still, there will be tricks to be learned. You will probably need a hacksaw or some tin snips, and then some other tools. Air holes are normally drilled with an electric drill.

–B.G.–

Bob,

Any tips on doing a good small "brake" ? for precise folds and bending?

"Any tips on doing a good small "brake" ?"

You know, that is one shop tool that I don't have. I've needed one several times in the past year, and I don't even know where I can borrow one.

There are some hand tools that you can purchase cheaply, and you can make a rolled edge on soft metal. That is about as far as I will go, I think.

I managed to put a rolled edge on some titanium foil. However, titanium seems to be a bit on the brittle side if you get the edge formed too sharply.

–B.G.–

I'd recommend the .003" titanium from Suluk46. I made a cone with an inferno insert for woodburning with a fosters pot. The cone is .5 oz. Complete woodburning setup (cone, internal cone, grate, and 'floor' is 1.5 oz. For closure, i just did tabs with slots and holes for tarp stakes to hold up the pot (I did two sets, one higher for woodburning and one lower for alky).

the photo's a little deceptive do to the wide angle, but the cone is slightly taller than the Fosters can.

Thank you for all the info. I should have done it today. Instead I made another pair of shoes. What is the matter with me???

Maybe I can make a cone tomorrow. The only reason I want one is for my alcohol stove so that I don't even need a fancy stove that lets me set the pot on the stove, just a cup to hold the alcohol.

After seeing the Fosters can above, I wonder if I could just put a cut half of a Fosters can around my alcohol stove as a pot stand/wind screen. Punch a bunch of holes in it for ventilation. Maybe that's all I really need.

A Caldera cone is effective because it represents an almost perfect wind screen for whatever is burning inside it. The size of the holes, the quantity of holes, and the placement of holes are each kind of non-trivial.

The second thing that is effective about it is that it holds your cook pot just right.

You could produce something very easily that accomplishes some of these two points, but it probably won't be as light.

–B.G.–

Hi Piper,
I live in SB and I have an aluminum caldera cone — if you want to come play with it for inspiration, let me know. I'm thinking of upgrading to an ULC version to fit in my pot, but I'm also toying with the idea of hacking up my aluminum cone with my utility knife… Anyway, shoot me an email at echaplin at gmail dot com if you'd like to see a cone in the flesh before you get started. Cheers, Liz.

"Bob,

Any tips on doing a good small "brake" ? for precise folds and bending?"

I'm not Bob..but…

I've made ~5 cones of varying quality before finally really getting it to look really nice (the others were functional, but I'm an engineer, form and function are both important when I have to look at it all the time). The lack of an angle brake/press brake of my own is generally the most difficult part of making one. What I've found works best is this:

Find an end table, coffee table, piece of wood/board, counter top, or other rigid thick surface with a very sharp 90 degree edge. Rounded edges won't work.

Next, find a book that is at least as tall as your edge that you're bending is long. It needs to be a hard cover book. Any other flat stiff object will work here though, a board, piece of metal, etc.

Place the edge you wish to bend over the edge of the table/countertop, overhanging the amount you wish to bend over the edge of the table/counter.

Place the book on top and roll over the edge of the table/countertop, bending the metal as you roll the book. This will get you to approx a 90 degree bend (just a shade under due to spring-back).

From here you can flip the metal over so that the newly bent edge is facing upwards. Use the book to press the surface down to make the bend 180 degrees.

Depending on how close that gets me to a 180, I'll sometimes pinch the edge down with a pair of pliers.

This is how I've finished the connecting edges (in place of the dovetails the production calderas use) on all of the cones I've made.

Hopefully those instructions make sense…using those and the youtube video on constructing a cone, you should know enough to be dangerous ;)

> http://www.youtube.com/watch?v=VerP7-aiEBw

This has a measurement error in it. When using this method to determine the radii for the conic section, use the red lines (on the sloping side), not the central black line as suggested.

Either that, or use my script for creating templates…

Piper —

Take a steel rule or some flat stock, the thickness of the fold and clamp it and the stock together. I use my workmate, but you could do the same with a pair of 2×4 and C-clamps.

Extend the edge of the cone material about 3/8" beyond the flat stock.
Take a piece of hard wood and slowly work the cone material around the edge of the flat stock. The thinner the flat stock the smaller the bend radius.

I can post a picture if the description is unclear.

You should be able to produce a nice fold which will interlock.

The trick will be in placing the fold so the correct diameter is produced to hold the pot.

I leave the geometry of the cone up to you. It is all high school geometry.

Vent holes can be drilled with a spade bit if you have a very light touch. You may want to clamp the sheet between two pieces of wood.

You only need nice, sharp, precisely positioned folds if you intend to copy Trail Designs' design closely.

There are plenty of other joints that can be used that are simpler to make, simpler to mate, and just as robust and reliable. I use a simple slot and tab joint for my clones.

For instance:

Admittedly, this uses a folded reinforcement on the edge. I make this by running a fine-tipped ball-point pen along a ruler to pre-form the fold, and then complete to fold with a thumbnail, or spoon, or similar smooth tool.

Kevin — nice job. Not sure how you get at the pot handles, but just a detail.

The interlocking joint would be tough to hit. Your idea is much better. The folded edge is needed for stiffness.

Nice! Any more photos? I can't figure out the connection from the description.

I decided to google for very small sheet metal brake and came up with this:

http://www.amazon.com/Sheet-Metal-Fabrication-Bending-Forming/dp/B004GYUJ84

Kevin; a program to make/print a template for the screen?

Wow I'm really seriously impressed!

Tim & Cola,

Thanks for the compliments.

There are no handles on that MSR Titan; I’d taken them off, and used a pan grab instead. They’re now re-fitted, and the handle opening extended. Actually, I use Flissure versions of the clone now, with a horizontal split & joint.

> The folded edge is needed for stiffness.

That’s exactly right; in the thinner foils I have access to, the edge tends to bow out slightly. Adding the little triangular fold stops that. In thicker foils such as aluminium roof flashing, the fold may be unncessary, or simply a double thickness.

There are plenty of example clones, of all shapes and sizes, to be found on the Outdoors Magic thread. Fast forward to the last few pages, as the thread’s pretty long. Or use the print thread version to see the thread in one go… You can chart the development of the script from an initial throwaway thought, through to what is now a fairly-well refined design tool. And, along the way, I added, and then removed, a mitre joint generator, replacing it with the simpler slot & tab joint which seems perfectly good enough.

The number of script users is almost 100 now… it allows you to create a custom clone for any size pan and burner, and a whole bunch of other esoteric settings. It will generate a horizontally-split clone that will generally fit inside the pan it supports (Flissure option), an inner cone for wood burning (the Infernal option), and my own variant, the Strata ring, which allows the use of one cone with two pans (within reason). The latter is pretty hard to make, but not impossible. For those without a printer, it also displays a “draughtsman’s construction”, giving the inner and outer radii and horizontal extent, allowing a simple clone to be made by scribing arcs on foil, or on to a template.

PM me with an email address if you’d like the script and instructions document. It’s free.

Kevin — If the pot has a handle, wouldn't it be better to place the cutout opposite the joint instead of at the joint, which shortens it?

I'm guessing this method is lighter in weight than having it on the other side.

–B.G.–

Tim,

If you're using a folded joint then yes, keeping the joint as long as possible may be good.

But for my slot & tab joint method, I've found that it really doesn't matter where it is, as far as joint strength is concerned, because the interlocked slot and tabs are the same size wherever they are. The joint is usually at least half the depth of the cone, for the pans I've used, anyway; I can imagine a very tall pan with full-height handles might have less, but I don't have any such pans…

The other reason for keeping joint and handle together is that the handle opening provides a natural weak point in the entire structure, and, in stiffer foils that aren't 'encouraged' to hold their shape, the tips of the opening can tend to bow out away from the pan. If the opening and the joint are on opposite sides, you have two weaknesses in the cone circularity. The overlapping of the joint helps to keep this issue under control a little. I also usually keep the handle openings pretty tight, so care is needed when putting the pan in the cone. If the joint were on the opposite side, I'd have to take care not to pop the joint open whilst negotiating the pan into the cone.

It's always best to pre-bend the cone by rolling it up into a tighter cone, so that, when released, it relaxes into just about the right size cone to fit the pan, so that little or no encouragement is needed to make it form the right-sized cone. Concentrate especially on the area around the pan opening, as this is where the cone will tend to bow out, as the conic section is interrupted by the opening.

In the Flissure split version, there's no vertical joint at all in the upper section (which has confused a number of users of the script), so the ends of this must, by necessity, be at the handle opening… I find that the horizontal Flissure joint, when mated, allows the foil to act pretty much like a single piece of foil, due to the overlapping joint, and the conical shape which holds the joint securely in place; once formed into a cone, the Flissure joint cannot be pulled undone, because the base up the upper half conic is a larger diameter than the top of the lower half conic.

Have a play with this idea; you can tell the script to make a very shallow handle opening, and then make one with the required depth, and put the handle openings on the first template. Or you could just use the basic template and draw the opening by hand (shock horror!). You might find it works better than I have.