=Choice between Blowpipe and Bit.=--The method of heating depends on the size of the work, or rather the area to be soldered, and the conveniences at the command of the worker. The soldering bit, although so commonly used, is not necessarily the best for the beginner to use for small work. A blowpipe flame--from a bunsen burner or a spirit lamp--is far more convenient and neat, and its effects can be applied and localised with the greatest precision, down to the merest pin point of heat applied at a definite spot. The bit is chiefly useful for long joints such as in tinplate work, and for pieces bound together to which the bit is applied to heat up and melt solder between them. But for work where the soldering area does not measure more than an inch or so (and there is a vast amount of this kind), the blowpipe flame is far preferable. It must be admitted, though, that this is a matter in which some workmen might have two distinct opinions; and, as already remarked, the bit is far more commonly used.
[Illustration: Fig. 3.--Pivoted Soldering Bit]
=Copper Bits.=--The soldering bit or bolt (miscalled an “iron”) carries a pointed lump of copper at the end (Fig. 2), riveted in, or alternatively, in small sizes, screwed on to the shank. Some bits are pivoted (see Fig. 3) to enable them to point at various angles for dealing with difficult situations.
A home-made bit (Figs. 4 and 5) may be made by drilling and tapping a short length of 1-1/2-in. or 2-in. square copper to receive the screwed end of a rod of 5/16-in. iron, the copper being afterwards heated and drawn to a point or to a blunt edge as preferred. This forms a good bit for most ordinary purposes. An axe-head or hatchet bit is shown in Fig. 6; the copper bolt is riveted in the eye of the iron rod, the bit, however, being free to revolve, as this is essential when making joints in heavy lead pipe, for which purpose it is principally used. Fig. 5 represents a bit which is a combination and modification of the two others, and it is largely used for the internal soldering of bottoms of large drums, milk churns, etc., where great local heat is required.
[Illustration: Fig. 4.--Home-made Soldering Bit]
[Illustration: Fig. 5.--Bit for Internal Soldering, etc.]