Fig. 407.
To avoid the difficulty of having some of the bolt ends project farther through some nuts than others on a given piece of work, as is liable to occur where the flanges to be bolted together are not turned on all four radial faces, the form of nut shown in [Fig. 407] is sometimes employed, the thread in the nut extending beyond the bolt end.
Fig. 408.
As an example of the application of this nut, suppose a cylinder cover to be held by bolts, then the cylinder flange not being turned on its back face is usually of unequal thickness; hence to have the bolt ends project equally through the nuts, each bolt would require to be made of a length to suit a particular hole, and this would demand that each hole and bolt be marked so that they may be replaced when taken out, without trying them in their places. Another application of this nut is to make a joint where the threads may be apt to leak. In this case the mouth of the hole is recessed and coned at the edge; the nut is chamfered off with a similar cone, and a washer w, [Fig. 408], is placed beneath the nut to compress and conform to the coned recess; thus with the aid of a cement of some kind, as red or white lead (usually red lead), a tight joint may be made independent of the fit of the threads.
