Page 454 - Robot Builder's Bonanza

MAKING SEMIPERMANENT CIRCUITS WITH WIRE WRAPPING 423

Figure 33- 8 Wire wrapping creates
circuits by literally wrapping wire around
metal posts.

Wire wrapping sockets use extra- long square- shaped pins (also called posts) that can
accommodate up to about five wrapped wires. Using a special tool, as shown in Figure 33- 8,
each wire is wrapped around the pin like figures on a totem pole. Once the wire is wrapped
about a half- dozen times around the pin, the connection is as solid and secure as a soldered
joint.

CHOOSING A WIRE WRAPPING TOOL
You need a special tool for wire wrapping. A manual wire wrapping tool is shown in Figure
33- 8. To use it, you insert one end of the stripped wire into a slot in the tool, then place the
tool over a square- shaped wrapping post. Give the tool 5 to 10 twirls, and the connection is
complete. The edges of the post keep the wire anchored in place. To remove the wire, use
the other end of the tool and undo the wrapping.
Other tools are motorized, and some automatically strip the wire for you, which frees you
of this time- consuming task (or the need to purchase the more expensive prestripped wire). I
recommend that you start with a basic manual tool. You can graduate to other tools if you find
wire wrapping suits you.
Successful wire wrapping takes practice. Before you build your first circuit using wire wrap-
ping techniques, try your hand on a scrap socket and board. Visually inspect the wrapped
connections and look for loose coils, broken wires, and excessive uninsulated wire at the base
of the post. Most wire wrap tools are designed so one end is used for wrapping wire and the
other end for unwrapping. Undo a connection by inverting the tool, and try again.

WIRE: SPOOLS OR PRECUT

You can purchase 30- gauge wire for wire wrapping by the full spool, but unless you’re going
into full- fledged production, a far easier method is to get precut wire in a couple of different
lengths—2″ and 4″ lengths make for a good start (that’s the length of the wire not counting
the bare ends).
When using spools, you must cut the wire to length, then strip off the insulation using the
stripper attached to the wrapping tool. A stripper for regular wire does a poor job because the
insulation on wire wrapping wire is extra tough. These steps greatly add to the time it takes
to make a single wire wrapped joint.

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