Brazed Joint

Brazed Joint is the union of the cleaned, brightened, and truly fitted edges or surfaces of brass, copper, iron, and gunmetal, by hard soldering, which is effected by temporarily steadying or binding them well together, and melting between them an alloy called spelter solder, consisting of equal parts of zinc and copper when surfaces of brass are to be joined, and of 3 parts of copper to 2 of zinc when copper or iron is brazed. The former variety is called hard spelter and the latter soft spelter, but they are both technically hard solders. Silver solder consists of 3 or 4 parts of silver to 1 of copper, or 2 of silver to 1 of brass; and it renders some joints - for instance, those of band-saws - less brittle. These solders are likewise known as hard, but that containing the most silver is relatively the hardest. The spelter solders are used in a coarsely powdered or granular form, the granulation being effected when making the solder by emptying it, after it has been exposed for a few minutes to a glowing heat, into a pail of cold water, and agitating it violently with a broom. They are worked into a mass with borax and rain or pure water, and previous to adding the borax it is advisable to burn it, with the object of driving off its combined water. When thus prepared, the paste is carefully spread or plastered over the surfaces to be united, and the heat applied from the clear fire of a forge with the aid of tongs, or with the flame of a gas blowpipe, - in either case gently at first, so as to evaporate the moisture and prevent the borax and spelter from drying away from the joint. Silver solder is divided into very small square plates, and the powdered borax may be used either dry or wetted with water. On becoming cool, the joint is cleaned off with the file and emery.

Capped Joint

Where copper is used as a roof covering this is identical with the corresponding joint of the Zincworker.

Copper Roll Cap Joint

Copper Roll Cap Joint is an alternative name for the preceding joint, and is made similarly to that of the Zincworker, with solid ends to the roll caps.

Cramp Or Cramped Joint

This is a term employed to designate a mode of joining thin sheets of brass, copper, or other hard metal, by tapering off the edges very thin, scoring a row of notches with oppositely inclined snips along one of them, as in Fig. 157, bending them alternately up and down, as in Fig. 158, and inserting within them the other edge, as shown in Fig. 159. They are then hammered and brazed with borax and spelter, and hammered and filed smooth.

Fold Joint

This is a similar joint, and made in the same way as the corresponding one described under the Zincworker.

Folded Joint

Folded Joint is the same as the corresponding joint in Section XI.

Lap Or Lapped Joint

This is represented in Fig. 160, which shows a mode of forming the joint with thinned edges.

Lightning Conductor Joint

Lightning Conductor Joint is used in connecting the various sections of the conductor, and, as may be imagined, many different forms of the joint have been devised to insure continuity. It can only be observed here, therefore, that as a rule iron should be brazed to other metals, in order that rust may not interfere as an insulator, whilst, perhaps, copper sections are best united either by riveting followed by brazing, or else by giving the ends a cylindrical or circular form, upon which a screw thread is cut, and joining the screw ends by means of a suitable and tight-fitting screw socket piece. The attachment to the building protected is by hooks or staples, and should be as close and complete as possible, insulation being perilous, and to be most carefully avoided.

Lightning Conductor Joint 158

Fig. 157.

Lightning Conductor Joint 159

Fig. 158.

Lightning Conductor Joint 160

Fig. 159.

Lightning Conductor Joint 161

Fig. 160.

Roll Joint

The same as Capped Joint.