Background
Dry corn (Zea mays) can be shelled using just your hands. If it forms a large part of your diet or you need a lot at once, this job can be time consuming and make your hands sore. There are several tools that can make this process faster and easier.
Currently the most popular option for small-scale corn shelling in North America seems to be a cast iron, hand-cranked device that can shell upwards of 10 bushels an hour. That’s excessive efficiency for my family. Why use a complicated machine when a simpler one is sufficient?
An intermediate option is a hand-held cone with ridges running the length of the inside. A cob is inserted in the wide end of the sheller and twisted through, with the ridges knocking off the kernels. If the large end of the cob doesn’t fit through, you can flip it end for end to get the last few kernels. The commercial versions of this type of sheller seem to be more available in subsistence corn cultures, but they can be obtained in Canada. But they’re structurally simple, so why not make your own?
The commercial hand shellers are made of plastic or metal. Plastic has a number of well-recognized environmental drawbacks. Metal objects have relatively high embodied energy. If you want to deal with that concern at home, you could use repurposed sheet metal (even a metal can could work) or repurposed aluminum cast using charcoal. To me that seems like extra work just to incorporate less resilient technology into my food system – I’d rather use metal only where it’s really needed and not rely on scavenging – so I went with wood instead. If you’d like to go with metal (which will admittedly last longer), MIT has very helpful instructions.
Instructions
Here are instructions for how I went about making a corn sheller. If you lack the tools and skills but still like the idea of a handmade wooden corn sheller, we also sell them.
This project involves using some sharp tools. You are responsible for your own safety. Once you understand the process, think through how you can do it safely with your tools in your context.
The goal is to make a tapered conical hole through the middle of a piece of wood. The ridges (teeth) will knock off the kernels, and the troughs between them will let the free kernels fall out of the sheller. The taper assures that the sheller can work along the variable diameter of each cob.
Start with a log at least 4 1/2″ in diameter. Green wood is easier to work with and will have less checking (cracking) in from the ends. Pick a hard wood so that the teeth will wear more slowly; I used ash.
If the end has checked a bit, cut it off. Then cut a length of 2″-4″. Longer should wear more slowly, shorter will be a bit easier to use, especially if you have a short-cobbed corn variety.
Mark out a big cross on the centre of one end and a small cross on the centre of the other end. Suggested dimensions shown in the picture:
The dimensions are flexible. Make the arms of the large cross shorter if your piece of wood is smaller diameter, but leave enough depth so that kernels can fall through the troughs without jamming. Make the hole in the middle of the small cross a different diameter if you have particularly large or small cobs. If you’re making several shellers, it’s worth your time to make a template to trace from.
Drill out the core from both faces, meeting in the middle. This will make chiseling a lot easier, but if you have a mortising chisel, you can probably do without the drill. For my dimensions, a 3/4″ bit stays just inside the lines.
Make shallow cuts on the outline of the small cross to prevent chipping out, then begin chopping out each arm of the cross into the centre. A mortising chisel will enjoy this job more than a regular chisel, but if you’ve drilled out the centre a regular chisel will work.
Cut vertically until each arm is opened out, then start slanting the cuts outward to meet the lines of the large cross. At first you can do this from the bottom, continuing with a mallet, but once you get near the lines of the big cross you should switch to paring while watching the top. You don’t want to cut too wide an angle and end up outside the line.
Once this is done, sight along each tooth and pare it straight. You can leave a little bump or more cylindrical section at the bottom end so that for a while the taper will just move downward as it wears without widening the small opening.
The sheller is now functional, but you can make it prettier and nicer to use by splitting the bark and extra wood off the outside, smoothing the splits, and chamfering all the edges.
Use as described above. Don’t hold the sheller completely horizontal or the loose kernels will tend to fill up the troughs and plug. Work inside a container of some sort or corn will go everywhere.
Please send feedback on the instructions or design so we can improve them, and let us know if you made one!