Simple and Inexpensive Wire-Wrap Tool While trying t o use engineering drawing lead as an inert electrode for potentiometric titrations, it became apparent that a mechanically secure connection was needed where coooer wire contacted the eraohite electrode. Pencil lead is somewhat -~~~~~~~~ frapile and is difficult to attach t o cnooer wire without breakine or formine a noisv ~
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purchase. Using a piece of '18-in. and a piece of %in. o.d. brass tubing obtained from a nearby hobby shop and some rosin core solder, a suitable wire-wrap tool was quickly and easily constructed using a Bunsen burner and a short piece of wood dowel. The smaller tubing was cut to 4 crn length and the larger tubing was cut to 8 cm. The pieces of tubing were held in place by wrapping with Nichrome wire; the tubing assembly was heated in a Bunsen flame until the solder melted to join the tubes uniformly. The wire was removed after the assembly cooled. A hole was drilled in the dowel and the brass tube was friction fitted into the drilled dowel handle. The cost was about $3.00 for the materials. The figure a t the right shows the finished tool. About 4 cm of stripped wire is pushed into thesmaller tube, and the pencil leadelectrodeis insertedabout 'I2in. into the larger tube. The wire is held with the electrode, and the tool is rotated to form a tight spiral as shown in the figure a t the right. The electrical contact is excellent and mechanically secure. This tool works well for any wire-wrap application.
Howard P. Williams
Leslie Cuccaro BOX5043 Southern Station
Haniesburg. MS 39406
788
Journal of Chemical Education
