Figure 8-7. - The first hole cut acts as a guide for drilling through the floor plate.
In the case of a wall cavity without tire stops or purlins, the alignment tool is used to snap the bit back to the inside wail (fig. 8-8) at which time downward pressure on the drill motor will keep the bit point in place and cause the shaft to bow. Power and pressure are then transmitted from the back wall that allows proper angle drilling to miss the joint boxing.
After the bit has penetrated into the basement area, as shown in figure 8-9, the operator has access to the hole in the drill bit itself for attaching the recovery grip and pulling the wire up to the outlet location-all without damage to existing finishes.
Figure 8-8. - Alignment tool used to snap the bit back to the inside wall.
Figure 8-9. - Bit has penetrated into basement area.
Figure 8-10 shows how the recovery grip is attached to the bit tip eyelet. The swivel, located between the cable and the head of the grip, prevents the wire or cable from becoming twisted during the fishing process.
Figure 8-11 shows the grip after it has been attached to the bit tip with the line inserted, ready for recovery. The operator uses the drill motor in reverse and applies a slight pull. The wire then can be pulled easily through the holes because of the reverse cutting action of the bit. If desired, the drill motor can be removed from the shaft and a recovery grip attached to the chuck end of the shaft for pulling the wires downward toward the basement. While this example shows the method of routing wires or cables from an outlet to a basement, the same procedure would apply for drilling from an outlet opening to an attic space.
To install contacts on windows for a burglar-alarm system, drill from the location of the contact through the casement, lintels, and plates with a 3/8-inch (0.9- cm) shaft. Attach a recovery grip to the end of the bit, insert the wire to keep the grip from becoming tangled, reverse the drill motor, and bring the wire toward the operator as the bit is being withdrawn.
Burglar-alarm contacts or door switches installed at doors are simple projects when one uses the flexible shaft. First cut or drill the entrance hole in the normal manner and then insert the flexible shaft with bit intoContinue Reading