Compass Table

Step 3 Route out the tabletop

The table top is made from three different layers of 12mm sanded plywood in order to get the right depth for the compasses and overall table top thickness.

Two 18" circles were routed out using a Jasper Circle Jig (a tool that I'm quite fond of).  A third circle of the same size was cut, and then had a slightly smaller circle inscribed inside of it to create the rim for the table.  The rim turned out to be 1/2".

Comments

[MarkMain]

 I thought of a pretty cool trick for making the compasses move around more often. Make an electronics project where you places small electric coils around the table by drilling small holes underneath (cap the holes to weather proof them and maintain them if needed) so they are very close to the surface without being seen. I'd recommend either just 1 in the center or 3, 4, 6 or 8 spaced even near the rim's edge (or slightly inward for a different effect) and optionally one dead center.

A controlling device when turned-on will send electricity to each of the electronic coils for a few seconds and then switch to another coil--this will guide the compasses move about as they also point into the direction of current magnetic field. The pattern can be in a circular motion, or with the center coil used in addition to the rim locations, you can move the field about in a gyroscope pattern--like this pattern: 12:00, center, 4:00, 2:00, center, 6:00, 4:00, center, 8:00, 6:00, center, 10:00, 8:00, center, 12:00, 10:00, center, 2:00, then repeat; a star pattern movement is possible; spoke pattern of center 12:00, center 3:00: center 6:00, center, 9:00, repeat; or simply a random movement.

You can slowly transition the movement by having electricity at two locations for a short bit and than slowly increasing the amperage (less resistance) to one coil while reducing the amperage (by increasing resistance) from another.

The coils need to be fairly small because you don't want to stop someone's pacemaker and it won't take much to move the compasses either.

You could also provide a motion sensor underneath to automatically turn the electronics on--it's a simple timer that would stay on for about 10-minutes, and then each recognized movement simply resets the counter. So it stays on until all movement has stopped for 10-minutes total.

Instead of a motion sensor, a vibration sensor could pick up tiny vibrations of the compasses.

You would want an on-off switch just in case someone with a pacemaker were going to sit there for awhile and you wanted to be absolutely safe. If you wanted to be really safe about this, then use more, but smaller, coils to create the magnetic field. A refrigerator and your flat screen panel generate electric fields and this thing could be made to create less field than that so I don't see a problem here, but a failsafe on-off switch is always a good idea just in case grandpa with the pacemaker wants to nap right on the table. :)

[Valster]

Mark, your idea would be fantastic as a wall hanging.  You would not have to sit at a table to see it. Everyone could watch it work from anywhere in the room. The only limits you would have are the size of your wall and the size of your wallet!