The electric soldering iron (fig. 9-23) transmits heat
to the copper bit after the heat is produced by an electric
current that flows through a self-contained coil of
Electric soldering irons are rated according to the
number of watts they consume when operated at the
voltage stamped on the iron, and the diameter of the
copper bit in inches (table 9-7).
There are two types of bits on electric irons. They
are plug bits that slip into the heater head and that are
held in place by a setscrew, and screw bits that are
threaded and that screw into or onto the heater head.
Some bits are offset and have a 90-degree angle for
Figure 9-23.--Soldering irons
soldering joints that are difficult to reach.
Electric iron bits must be securely fastened in the
A nonelectric soldering iron (fig. 9-23) is sized
heater unit. The bits must be clean and free of copper
according to its weight. The commonly used sizes are
oxide. Sometimes the shaft oxidizes and causes the bit
the 1/4-, 1/2-, 3/4-, 1-, 1 1/2-, 2-, and 2 1/2-pound irons.
to stick in place. Remove the bit occasionally and scrape
The 3-, 4, and 5-pound sizes are not used in ordinary
off the scale. If the shaft is clean, the bit will receive
work Nonelectric irons must be heated over a gas
more heat from the heater element, and it will be easier
to remove when you need to replace the bit.
Table 9-7.--Selection of Soldering Iron for Work to be Done by Copper Bit Size
Work to be done
Choice of Bit Dia.
Heat Rating Watts
Size of Bit, lb.
1/4 to 7/16
Very light soldering.
3/8 to 1/2
Medium soldering of electrical
appliances and light manufacturing.
3/8 to 9/16
Fast soldering on radios, electrical
appliances, and light medium
Medium light soldering on tin ware,
5/8 to 7/8
plumbing, and wiring.
High-speed soldering of light tin
5/8 to 1
ware and small metal patterns.
Medium manufacturing such as
7/8 to 1-318
ventilation ducts and other shipboard
Heavy tin ware, metal patterns,
1-1/8 to 1-3/8
galvanized iron and copper.
Heavy ventilation ducts, tanks,
1-3/8 to 1-7/8
plumbing, and ship building.