How Do Self-Centering Drill Bits Work?

Self-centering drill bits make easy work of drilling perfectly-positioned holes. Where would you use them, how do they work, and how do you use them?
Read on to find out.
Carpenter fixing hinge with Self-centering drill bits
This guide is about spring-loaded self-centering Vix bits or hinge bits. See here for split point bits that can directly drill on metal without spot drilling.

What is a Self-Centering Drill Bit?

Self-centering drill bits allow you to drill precisely centered holes with minimum effort.

This tool consists of a spring-loaded metal shell around the drill bit that allows it to center on the intended hole position and not skip on the surface. It stays centered in the workpiece while drilling, so the bit doesn’t wander, creating havoc in your workpiece.
A set of self centering VIX drill bits
This is particularly important when installing hinges since having one screw off-center can ruin the hinge’s functionality.

S E Vick Tool Co., a Minnesota based company developed this tool and hence it is widely known as the Vix bit. Most of these bits come with hexagonal shanks that fit in the impact driver socket or cordless drill with a self-centering chuck.

Uses of Self Centering Bit

The most common application of this bit is for drilling pilot holes to screw the hinges in position. Hence, these spring-loaded bits are often called hinge bits.

These drill bits are also useful when installing metal kick-plates, drawer slides, handles, or any other feature that requires accurate hole placement.

A wide variety of self-centering drill bits are available on the market, suited for use on metals, wood, and plastic. These bits are designed to stay perfectly centered while drilling, even if the material you’re drilling isn’t perfectly flat or even. This works even with grainy wood, where the grains tend to pull regular drill bits skew during drilling.

Why Do You Need a Hinge Bit?

When drilling hard material, using a dull drill bit, or when the bit catches on wood grain, it easily wanders, leaving an off-center hole.

You can sometimes remedy this situation by forcing the screw installed in that hole into the correct position. However, this is generally a bad idea. You would typically have to fill this hole with wood or wood filler, sand it down, and re-drill the hole. That’s a lot of effort for one screw and can be prevented using a self-centering Vix bit.

I don’t use the Vix bit when drilling metal using a drill press or milling machine since machine drilling is usually accurate.

On the other hand, positioning a drill bit exactly at the center of a hinge hole with handheld power tools is difficult. Regular drill bits also tend to walk or slip when working, especially when drilling metal or uneven surfaces. This causes inaccurate drilling and damage to the workpiece, potentially ruining the project.

These can be challenging applications for even the most experienced craftsmen. A self-centering hinge bit prevents this by ensuring that the drill bit remains perfectly centered during the drilling process.

The self-centering ability of this tool enables you to drill holes to precise dimensions without a drill press. For some projects, this is essential. Drilling through curved surfaces, like pipes, is another application infamous for slipping drill bits. Self-centered drill bits enable accurate drilling here, too, since they gain a better grip on the material, allowing for a straighter hole and neater drilling.

How Does it Work?

A self-centering hinge bit consists of 5 main parts.

  1. The main body (usually with hexagonal shank)
  2. Moving sleeve
  3. Outer shell
  4. Drill bit
  5. Spring

Parts of a self centering hinge bit
The drill bit is fixed at the center of the shank and clamped with a set screw from the side. The sleeve surrounding the drill bit is spring-loaded and moves inside the outer shell.

This sleeve has a tapered tip that slips into the tapered hole of a hinge or other feature you’re installing, such as a metal kick plate.

Self-centering drill bits come in various sizes, allowing you to match the drill bit to the feature you’re installing. When sized correctly, the tip fits securely into the tapered hole, keeping the drill bit in a steady position, as long as the part you’re installing doesn’t move.

Working Principle

Initially, the tip of the drill bit remains inside the spring-loaded sleeve.

Position the tip of the sleeve in the matching hinge. When drilling, as you push the drill bit down, the spring-loaded sleeve remains in place. Here, the sleeve guides the drill bit to remain perfectly centered and straight.

When you remove the drill bit from the workpiece, the sleeve moves back in place, covering the drill bit once more.
Parts of a Self Centering Hinge Drill Bits
The sleeve has an oval-shaped vertical hole on the side, allowing wood shavings to exit the drilling hole. This prevents material build-up inside the drilled hole and the shell.

The self-centering functionality is aided by the steeper 135° point angle of the twist drill bit. You can also use a brad point bit which has a small point in the bit’s center that grips securely into the material, keeping the bit from shifting.

How to Use a Self-Centering Drill Bit?

Using a self-centering drill bit is much the same as using a regular drill bit. Here’s a step-by-step guide.

  1. Prepare the workpiece. If you’re installing hinges or kickboards, first mark the location of the installation. If needed, route out the area to ensure proper installation.
  2. Mark the drilling position. Using a woodworking pencil, mark the hole position. If you’re installing a hinge, kickboard, or similar feature, place that in the required position. Mark the holes, but keep the hinge in position. You’ll need this in later steps.
  3. Secure the workpiece. If you’re an experienced craftsman installing small features, it might be sufficient to hold down the feature using one hand. Typically, it’s best to secure the installation using a clamp.
  4. Install the drill bit. Install the self-centering drill bit into your hand drill as you would any other drill bit.
  5. Place the drill bit in position. Ensure that the tapered end of the spring-loaded sheath fits securely into the hole of the hinge. This ensures that you will drill a perfectly centered hole. Hold the drill in a vertical position.
  6. Switch on the drill and drill the hole. Apply even pressure to the drill bit until you reach the required depth. Be sure to drill slowly, as this allows you greater control over the process. Remove the drill bit once the hole is complete.
  7. For deep holes, remove the drill bit from the hole after every ¼”. This prevents material build-up in the hole and sheath.
  8. Repeat the process for the remaining holes.

Install screws into the newly drilled holes. You can do this using the correct drill bit and the clutch setting on your handheld drill.