It often happens that in boring for the lag screws the bit strikes a nail and further progress at that point seems out of the question. When so situated, take your bit out, and running the lag screw up as far as it will go, by sheer force swing it three or four turns up further than the point where your bit struck. Removing the lag and replacing the bit, it will be found that the nail has been forced aside and the way is now clear.
Hook bolts (Fig. 42) or--as our across-the-sea cousins call them--"elbow bolts," despite all assertions to the contrary, are an easy, safe and economical stringer fastener or suspending device.
Figs. 43 and 44 illustrate two very common abuses of the hook bolt. In the one (Fig. 43), instead of the bolt proper lying snug up against the beam flange with the whole of its hook resting squarely upon the beam's flange, its supporting countershaft is turned into a menace to limb and life by this "chance it" kind of erection. In the other (Fig. 44), though the bolts do lie snug against the flange, the hook being out of sight and no means being provided for telling whether the hook lies, as it should, at right angles to the web of the beam, even if properly placed at installation, timber shrinkage, vibration or a slight turn of the bolt when tightening the nut, all constitute dangerous factors tending to loosen or entirely loosen the hook's grip upon the beam flange.
Fig. 43 suggests its own remedy. As to Fig. 44, a screwdriver slot (made by a hacksaw) at the nut end of the hook bolt and running in the same direction as the hook, Fig. 45, will at all times serve to indicate the hook's position and, allowing as it does of a combined use of screwdriver and wrench, it can be used to prevent the bolt's turning when being tightened.
Where two or more hook bolts are placed close together on the same beam flange, a plate, preferably wrought iron with properly spaced confining pins for the hooks, may be placed between the beam flange and the hooks as in Fig. 46. Its benefits are obvious and so likewise is the use of a small, square, wrought-iron plate with a bolt hole through its center instead of hook bolts.
The various styles of beam clamps carried by the hardware and supply trade all have their good points, and though the _C_ of their cost may seem to loom large, it is not a whit more emphatic, taken all in all, than the _W_ of their worth.