Compass

25,991

23

15

About: Will Bosworth, developing projects for HowToons @ SquidLabs.

Intro: Compass

Always getting lost? Build this compass out of a CD and a small magnet.

Step 1: Parts Layout

a compact disc (hopefully used / useless)
a small magnet
the outer case of a 50 pack of cd's. (can substitute anything that will hold water and a floating cd, a cd-case looks nice)
some hot glue
some water

Step 2: Glue Magnet to CD

Glue the magnet pretty much anywhere on the cd*, with a pole facing radially outwards. If the magnet's pole does not face radially outward the compass will be decieving.

To find the poles, place the magnet in the presence of other magnetic objects. The magnets will attach to each other along their poles if they have enough mechanical freedom to.

  • Depending on magnet size, glue-ing too far away from the cd's center will tip the cd (think center of mass). But, if the magnet is too close to the center the torque arm length about the center will not allow for the compass to spin / function properly.

Step 3: Find North

lay the cd+magnet into a bowl of water and watch is align itself with north. The attached video shows the compass aligning itself (it's a kind of boring video)

Share

    Recommendations

    • Fix It! Contest

      Fix It! Contest
    • Tiny Home Contest

      Tiny Home Contest
    • Furniture Contest 2018

      Furniture Contest 2018

    15 Discussions

    0
    None
    Gorilla22

    2 years ago

    Sorry, where is the video?

    0
    None
    kthomas29

    6 years ago on Introduction

    I would like to build a compass with a CD but my design is a little different. I would like your opinion if it would work. I would oppose two ring magnets on a dowel, the top ring magnet would be glued to the CD, so then the CD would levitate with the dowel down the center. Then I would take some metal wire touching the top magnet and extend it out to the end of the CD. I may have to counter the balance with maybe a copper wire on the other side. Do you think this would work?

    I suddenly got an idea! *rips t-shirt* Oh man... Now all I need is a sheet of PET...

    0
    None
    ve2vfd

    12 years ago

    So simple yet what a stroke of genius! I'll definetly be using this when doing compass instruction with my Scouts in a few weeks! A floating CD and a magnet is a lot more 21st century than the old "floating cork and magnetized sewing needle" trick. Thanks! Great idea!

    1 reply
    0
    None
    ericscrumve2vfd

    Reply 8 years ago on Introduction

     Hey, the needle and cork has been around for years! (But this version looks like it could work a little better because the floating component has more surface area).

    0
    None
    ysabet

    10 years ago on Introduction

    NICE. Gonna try this one tonight! --puts on MacGyver disguise--

    0
    None
    Ingerson

    12 years ago

    Really stupid question: how do you know which is the North face of the magnet?

    1 reply
    0
    None
    PurpleJesusIngerson

    Reply 12 years ago

    Not a stupid question.
    1) build it, if it points away from the sun around noon (assuming your in the northen hemisphere) you have the southern pole of the compas magnet pointing toward the north pole.
    2) if you want to get elaborate or just play with electro mag's check out this link... pay special attention the various "left hand rules" and how the wires are turned...
    http://library.thinkquest.org/16600/intermediate/magnetism.shtml

    0
    None
    savagenarce

    12 years ago

    At last! Something that old CDs can be used for! Tip: balance the weight of the magnet with a counterweight on the opposite edge of the disk to prevent tipping. A washer or two hot-glued to the disk will work nicely.

    0
    None
    PeterTheUnGreat

    12 years ago

    Lovely simple Idea, the kids in my sunday school group are going to love making these! Pete

    0
    None
    skot123

    12 years ago

    We did this for a Cub Scout den project (pack 682 WA) this evening. We used a magnet from a Magnetix kit. We had a good discussion on compasses and magnetism. I had the magnet from a dismantled hard drive handy and we could see the repulsion/attraction from about 12”. The best part it got the scouts thinking; “What happens if you turn the magnet around?” and related questions and theories.

    0
    None
    mikesty

    12 years ago

    I'm so putting one of these on the dash of my first car :)

    0
    None
    wperry1

    12 years ago

    This is really cool! If you added a few vertical lines around the spindle lid this could even be accurate enough to take a bearing. I think I'll make one of these up and keep it hand for the coming apocalypse :)

    0
    None
    VelvetElvis

    12 years ago

    Simple and educational. Thanks.