It has occured to me to use some beer cans (after beer drinking), to make a very lightweight funnel for my small wood stove, which I use when I hike in cold days. I needed to stack up several cans one upon another to get the desired height. This small wood stove was designed to have a proper air/smoke draft with tube dia 50-65 mm, which corresponds to an usual beercan or similar cans of 0.5l. These, after use, cost nothing. This chimney is very lightweight for transport, but also very fragile - so handle with care. Removing the can bottom and top, only way to stack these upon each other is to create small wavy rim on one end, so as to get the smaller diameter. So I decided to construct a gadget that would help make the corrugated rim on one side of the can.
I cut two pcs from 10x80mm steel plate to make two squares of 90mm and 30 mm high. I purchased two toothed wheels of 20mm diameter and teeth height 2 mm, with 10 mm diameter axle. On both square plats I drilled the adequate10mm holes.
Step 1: Assembling
Two M10 screws serve as axles for both gear wheels. To the square plates I inserted two M5 screws to serve as adjustment bolts. I used epoxy metal glue to fix M10 nuts. The distance between gears can be adjusted with two M5 wing nuts, inserting as many washers as needed. Smaller gap makes depeer corrugating, therefore resulting in smaller diameter of smokestack tube. Testing will allow you to set a proper distance.
As the tubes from various cans is different - thickness, diameter, alloy, mainly related to the beverage producers concept, it is common sense that you choose only one type of product for your project, as mixing the different cans can be tricky.
I tested this gadget and it works very well for me, compared to those few stove chimneys which I made so far.
Another can type, which is stronger and longer is the can for tennis balls, usually 4 ball pack. Diameter is 65 mm and this can is made from steel sheet, - lenght about 400 mm.
See the video clip.
Krešimir Pregernik, dipl.ing.