If you have a low-powered soldering iron, you
may have trouble. Mine is only 25W and it did
OK, so anything above that should be fine.
Before soldering, clean the areas to be
joined by roughing them up using coarse sandpaper. Sand the end of the horizontal tube, and
all around the hole in the vertical tube.
Next, stick some solder onto the 2 tubes
before you attempt to join them. This is where
the flux comes in. Tackling one piece at a time,
liberally apply a coating of flux at the joining
point, and then heat the area with the soldering
iron while feeding solder into the area. When
the tube is hot enough, the solder should begin
to flow around the area to be joined.
Once each piece has a coating of solder, they
can be brought together and reheated. Clamp
the vertical tube to stop it rolling around, and
hold the short tube with pliers or thick gloves.
You may find it useful to use a blowtorch
instead of a soldering iron to gently heat the
pieces while you push them together (but be
careful, too much heat may discolor the metal).
You’ll now have the 2 pieces joined at right
angles (Figure C). If you have masses of solder
at the joint, just sand it down nice and smooth.
3. Drill the base.
Position the brass arm and the coil on top
of your box so the coil lies approximately
beneath the midpoint of the horizontal tube
(Figure D). Once you’ve found positions that
look right, mark the positions for the holes on
the box. As the wire coil has a hole in its center, you’ll probably want to offset the drill hole
for this so it’s hidden under the coil.
When you’re happy with the layout, drill
a 5mm hole for the brass arm. It should be
a snug fit. A smaller drill bit of 3mm can be
used to make the hole for your coil wires to
go through. Lightly sand both holes to remove
any rough edges.
magnet and gears are attached using epoxy
glue, which is more than strong enough to
hold everything together.
For hanging the pendulum, I added a short
loop of the enameled copper wire. I simply
looped it through the holes around the edge of
the gear, wrapped the loose ends back around
to secure it, then bent it upward to form a
peak in the middle (Figure E). Depending on
the weight of your pendulum you may need to
use slightly stiffer wire for a hanger, to stop it
deforming as it swings to and fro.
CAUTION: When using power tools, always wear
eye protection, work slowly and carefully, and follow the
operation and safety instructions in the owner’s manual.
4. Make the pendulum.
My pendulum is constructed using some old
brass gears to hide the neodymium magnet.
The main gear is 45mm in diameter, with a
smaller gear stuck on top for decoration. The
5. Wire it all together.
This is the tricky bit. The wires for the LED
and solar panels must be threaded through
148 Make: makezine.com/28