Vix bits are self centering drill bits used for drilling pilot holes when installing drawer slides, hinges and other cabinet hardware that requires precise alignment.
Most of this type of hardware has countersunk mounting holes that utilize flat head wood screws with a countersunk head. If you try to just eyeball your pilot hole and drill it a bit off center, the hardware will be pulled out of alignment when the screw is tightened.
Usually, the only way to fix a mistake like this is to fill the offending pilot hole with a glue/sawdust mixture and drill a new hole. If it's in an area that's already had finish applied, you may also have to refinish the area around the hole. Time consuming and avoidable.
A vix bit is also known as a hinge bit, centering bit or self centering drill bit.
The vix bit has a tapered end that centers itself in the countersunk mounting hole to give you a perfectly centered pilot hole every time.
There are several sizes available, but the two I use the most are the #5 and the #9. The #5 has a 7/64" drill bit for #5 and #6 wood screws and the #9 has a 9/64" bit and works for #8, #9 and #10 screws. You can buy them individually or save a few bucks and purchase a set like this 3pc Vix Bit 3,5,9 Hex Shank set from Amazon that will cover most jobs related to cabinetry.
The high speed steel drill bit inside the body of the vix bit is held in place with a set screw and can be easily replaced should you happen to break one. An allen wrench is usually included in the package.
A self centering drill bit has a two piece body, a drill bit, a spring and a plunger.
The photo on the left shows the parts that make up a centering bit. The drill bit is held in place on the upper part of the housing with an allen head set screw. The drill depth can be adjusted by loosening the set screw and moving the drill bit in or out.
The plunger sits inside the lower housing and is pushed to the bottom of the housing by the spring. A pair of slots cut into the sides of the plunger help evacuate wood chips. With the lower housing threaded onto the upper housing, you have a very simple but effective tool.
When drilling pilot holes for hinges, drill one hole and lock the hinge down with a screw. Then drill the other holes.
When the tapered end of the plunger is pushed into the mounting hole on the hinge (or drawer slide etc.), it self centers. As the drill bit starts to cut, the plunger retracts into the housing and the pilot hole is drilled perfectly centered.
The flutes of small diameter drill bits like these tend to clog with wood waste when run at the slower speeds of cordless drills, so it's best to use a corded drill because of it's higher rpm.
To insure your screws go in nice and straight, the drill needs to be at 90 degrees to the hole. A little attention to detail here will give your work a professional touch.
Hinges, drawer slides and other cabinet hardware are usually the last pieces to go on any cabinet job. Wouldn't it be a shame to go through all that work on your project and then botch it in the final steps? Vix bits make an otherwise tedious chore fast, easy and accurate.