Introduction: Beer Can Compass

This is a remix of a previous instructable:

A had read that a needle could be magnitised, floated through a cork or on a leaf to find North. But this instructable gave me the idea of floating a needle on something flat... like a piece of aluminum from a beer can. This can easily be stored or even kept in a wallet untill required.

A few extras can be added for a deluxe model.


Beer can
Packing tape
Printed compass rose


Step 1: Cut the Top and Bottom Off a Beer Can

* Cut the top and bottom off a Beer can.
* Trim with scissors.

Step 2: Tape the Needle, Magnitise

* Tape a needle to the aluminum sheet.
* Cut out a rectangle around the needle.
* Magnitise the needle by stroking it in one direction multiple times with a powerful (Neodymium) magnetic, say 100 times.

Step 3: Glue on a Compass Rose

* Print out a compass rose - I photographed a compass, saved the image as a pdf and then printed it, at a reduced scale.
* Glue on top of the needle, with North aligned with North pointing neddle.
* Cut to the desired size.

Step 4: Cut and Flatten a Beer Can

* Cut down the middle of the can.
* Straighten the sheet by rubbing along an edge.

Step 5: Cover With Clear Packing Tape

* Cover with clear packing tape to prevent the paper from getting wet.
* Test by floating in a bowl of water.

Step 6: Test

* Find magnetic North using a compass or an app on your phone.
* Float the beer can compass in a bowl of water. While aluminum is heavier than water, surface tension will keep it a float.
* Check that North matches the compass, If it is pointing the other way, remagnitise using the magnetic turned upside down. This will change the way it points by 180 degrees.


Step 7: Improvement 1 - Adjust for Magnetic Declination

Magnetic North usually points slightly away from true North. The difference is called 'Magnetic Declination' This is different for different locations.

To find the declination for your area, check:

The location I will be using the compass has magnetic declination of +12 degrees East.

I wanted the compass rose to point magnetic North but for the edge of the aluminum to align true North. This was achieved by having the compass rose point away from the edge by the location's declination. This will help when using the beer can compass with a map which points true North.

Step 8: Improvement 2 - Use a Clearer Compass Rose

The beer can compass was made easier to read with a simpler compass rose image. This was also aligned with the locations declination using image editing software.

Step 9: Improvement 3 - Add in Extras

i) Use the back for an inspirational slogan.

ii) Add in some thread, could be useful while camping.

iii) Adding in a pin hole will assist the short sighted to see if required.

iv) Print in colour for a 'delux' model.

Step 10: Inspiration From Defeat

After floating in water for a couple of hours the paper became wet. The tape wasn't making the paper waterproof.

While removing the tape, I noticed the photocopied rose image was sticking to the packing tape as the water logged paper was peeled off. Aha! let's use that!

Invisible thread can also be used instead of cotton.

Step 11: Field Testing

Well that should really be river testing. Attached half a beer can to the deck of my kayak, added some water and then floated the beer can compass in it. Worked a treat!. Showed that we headed out going East then came around a bend in the river and we began heading North/East. Ect..
Remained floating the entire time over our 12 Km kayak trip. Might use it next time to plot our route by recording our direction every 5 minutes. With an average speed of 6.5km/hr, these directions could then be plotted - showering our route.

Step 12: Improving a Toy Compass

Toy compasses, like the one I found in a Christmas cracker are notorious for not pointing to North correctly. They can be improved by disassembling the dial and then floating it in half a beer can filled with water. You can also re-energising it by giving the metal needle some strokes with a magnetic.
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