Page:Steamlocomotivec00ahrorich.djvu/37

 that these tools can be used on any portion of a boiler, in whichever part of the shop it may be standing. The holes for the short side stays are similarly reamered out and tapped.

The copper side stays are turned and screwed in automatic lathes. The threads have to be made very accurately, since it is essential that they should fit tightly into the “tapped” or screwed holes in the copper plates of the firebox and into the steel plates of the firebox shell. After having been screwed into position, either by hand or by a pneumatic machine, the ends of the stays are cut off to a definite length, which leaves a short length projecting on each side of the plates to be riveted over.

Tubes. The tubes are put in from the smokebox end, the holes in the front tubeplate being, for this purpose, made slightly larger than the outside diameter of the body of the tubes. The tubes themselves are enlarged at the smokebox end, and swaged down to a slightly smaller diameter at the other end where they pass into the firebox tubeplate. At the latter end the tubes project into the firebox for about ⅜ in. to allow for “beading over” the ends up against the copper tubeplate. They are tightened in the holes by means of a tube expander, a special tool provided with a number of rollers. This is placed inside the tubes, the metal of which is rolled outwards until they are a tight fit in the holes. In the