Cable installers have all kinds of tricks for fishing cables though walls.  Take for example a flexible drill bit.  A flex bit is just what it sounds like, a flexible bit.  The bit will flex so you can come in at an angle and direct the bit down through the floor or up through the ceiling.  The business end of the bit has a screw feed so when the bit gets started in the wood, it can help feed the bit.

You will find flexible drill bits in diameters ranging from ½” to 3/4” with 9/16” being fairly common.  You will also find varying lengths ranging from 48” up to 72”.  Obviously your job will dictate size but my thought with flex bits is that the smaller diameter the better just for ease of use.  You will also find two different shank diameters, 3/16” and ¼”.  The 3/16” will likely provide more flexibility but the ¼” will provide more stability for the job.

Most flexible drill bits will have a small hole in the tip of the bit.  This holes can be used to aid in fishing the cable.  Once you drill through, don’t pull the bit out yet.  Tie a piece of wire or a pull string through the hole on the end of the bit and then pull the bit out.  Now tie your cable on to the pull string and you can pull your cable through.  Good thinking!

For more control when using a flexible drill bit you may want to use a flex bit director or guide.  This handy little tool is considered a must my some to keep the bit on track.  It’s a pretty simple tool that ride on the shank of the bit giving you more direction or control.   Another neat little the deal called Bumper Balls by Rack-A-Tiers. (featured in video below) It’s simply a ball that slides down the shank of the bit that keeps the bit in check while inside the wall.  It will actually keep your bit somewhat centered inside the wall pocket preventing it from poking through the drywall.

Flex bits are one of those handy little tools that you don’t need very often but having the right tool for the job will always make your job just a little easier.