Do impact drivers need special bits?


Impact drivers are amazing tools that have become a staple of any handyman, carpenter, or woodworker. They are compact, powerful, and easy to use. Although it may seem like a straightforward power tool, impact drivers still require some knowledge and skill to utilize properly. One of the most asked questions usually asked is, does impact drivers need special bits?

The general consensus amongst tradespeople is that impact drivers can use regular hexagonal shafted ¼ inch shafted bits. However, most professionals prefer to use impact driver-rated bits because of their accuracy and durability. Impact driver-rated bits are also more suited for larger projects and are less likely to fail during use as they are specifically designed to endure higher torque levels.

For the purpose of this article, we will explore the difference between impact drivers and impact drills, the bits that are associated with them, and which bits are best suited to your projects. We will also expand why there is a difference between impact drivers’ bits and impact drill bits and the design and metals and materials of which they consist.

What is the difference between an impact driver and a drill?

First, let us distinguish between an impact driver and a normal drill or what is sometimes referred to as an impact drill.

It begins with something as simple as function. Impact drills are used to bore holes in metals, wood, rock, and other materials. This is done by a powerful motor that provides both speed and power to a rotating chuck that contains a drill bit, which pierces the desires materials with speed coupled with rotational force. While some modern models have variable speed settings to allow you to drive screws into your material of choice, the main purpose of a drill remains to bore openings or holes.

Impact drivers focus on using rotational force combined with high torque levels and an impact motion to drive screws into metal, wood, or stone. Impact drivers utilize motors to provide high levels of torque combined with a driving impact action to drive screws or fasteners into rigid materials. This is similar to the technology that hammer drills use but not as powerful nor heavy. Impact drivers are more compact and lightweight to help with the fastening of screws while in awkward positions or enclosed spaces.

Can you drill with drivers and drive with drills?

Although there is a visible and functional difference between drills and impact drivers, they do share some commonalities. And for this reason, they can be used as mentioned above to fulfill some of the other’s purposes.

Drilling with impact drivers

The same is true of impact drivers. They can be used to bore or drill holes in materials. However, because of the speed at which the hexagonal socket on an impact driver moves, you might not be able to penetrate some materials. This can also potentially also cause the motor to burn out on your impact driver. Another issue you might run into is that the drill bit might snap or be dulled when used, as some drill bits cannot be used in conjunction with the impact motion for which an impact driver is known.

If you are in a situation where you have no other choice than to use an impact driver as a drill, ensure that you know the density and tactile strength of the material you are drilling into, as this will determine the type of bit you will need. For softwoods, you should be able to get away by utilizing a standard hexagonal shanked drill bit. However, if you are attempting to drill into heavy steel or harder woods, you will need bits specifically rated for those materials.

The other risk you run when attempting to drill with an impact driver is bit damage or failure. As we will discuss in the next section, there is a difference in impact driver bits and drill bits. This is due to the metallurgic composition and design difference.

Driving with drills

For instance, you can use a drill to drive screws, but you run a higher risk of stripping the fastener or screw when doing this, as the power of the drill does not translate the power effectively into the fastener or screw. This can also lead to you stripping the bit. This means that the bit will not be able to grip other screws and become essentially useless.

Therefore, it is recommended that if you do want to use your drill to drive screws into wood, stone, or other materials, you are aware of the density and hardness of the materials into which you are attempting to drive in screws or fasteners.

You should also preferably own a drill with a driver setting or a variable speed setting, as this will decrease the chances of you stripping the fastener or damaging your bit. Depending on the density or hardness of the material you are attempting to drive fasteners into, the speed will vary. Using impact driver-rated bits will also increase the success rate for driving the fasteners as they are designed and manufactured to handle more stress than regular bits, as we will discuss later.

Unfortunately, drills that do not have driver settings rely solely on the speed of the motor to generate power, which increases the chances of the fastener stripping. Therefore, it is important to monitor the bit’s speed and ensure that you apply enough pressure force to the drill to ensure that the bit properly grips and drives the fastener.

Conversion kits for impact drills

Impact drivers exclusively use and handle ¼ inch hexagonal bits. Be aware that it is impossible to use normal drill bits with most impact drivers unless they have hexagonal collets.

If you find yourself in the position where you need to use an impact driver for drilling, as mentioned above. You can buy a chuck conversion kit that consists of a keyless chuck with a hexagonal shaft that attaches to an impact driver that allows you to fit conical or normal drill bits. This chuck attachment lowers the speed and torque with which the impact driver performs as it is quite weighty by itself. However, the drill bit chuck attachment provides more accuracy and stability and is therefore recommended for more accurate drilling. Before using a chuck conversion kit on your impact driver, make sure that your impact driver has enough torque power to drive the attachment.

This being said, it is still recommended to use a standard drill for most materials and hammer drills for harder and denser materials. As the saying goes, just because you can drive with your feet does not mean you should do it.

Difference between regular drill bits and impact driver bits

There are a few visible as well as invisible differences between regular drill bits and impact driver bits. Below we will discuss them and explain the function and design differences as well as the difference in metal composition between the different bits.

The biggest difference between normal bit and impact driver bits is that most impact driver bits have hexagonal shafts that fit into a hexagonal socket or collet. A collet is a socket into which the hexagonal bit fits and is connected to the impact driver’s motor. The shafts on the impact driver bits are hexagonal is because of the amount of torque and precision required when driving fasteners into materials.

The hexagonal collet on impact drivers is also designed to have bits changed quickly with a quick change clamp. The chuck on drills either need a key or need to be rotated multiple times before releasing the bit.

This is also because most drill chucks consist of a mechanism that has three clamps that can be adjusted to fit and secure different sizes of driving and drill bits.

Impact driver shaft design

Impact driver bits also have a different shaft design. For instance, they have a regular ¼ inch base that tapers to a thinner neck and extends back to a ¼ inch head again. These impact shafts usually are longer than standard driving bits as well.

The reason behind this design is to distribute the pressure along the thinner, more extended surface. It also allows removes the excess stress from the bit’s tip. These types of bits also have larger torsional strength than regular drill bits, allowing the impact bits to take more wear and tear.

Metal composition of impact driver bits

Impact driver bits are also made from a combination of metals that make them more ductile than regular or standard bits.

Ductility is a mechanical property that is defined by the degree to which a material or metal can sustain tensile stress through plastic deformation before breaking or failing. In other words, the amount a metal or material can flex before snapping.

Ductility plays a very important role in impact driver bits as it is directly connected to the amount of stress an impact driver bit can handle. It also ensures that the impact driver bit grips the fastener better and does not break while the impact motion is performed by the tool. Regular drill and driver bits are composed of more minor ductile metals and thus break and blunt easier when used in conjunction with the impact motion or denser or more rigid materials. 

Do impact driver bits still fail?

Although impact driver bits are designed and manufactured to handle more stress and torque than the average driver bit, mechanical and structural failure is still possible. However, in most cases this happens due to improper or excessive usage.

Excessive usage

Excessive usage happens to all tools eventually and is caused mainly by metal fatigue. Metal fatigue happens when the tool, or in this case, the impact driver bit, is put under stress that supersedes its ductile capacity. The metal absorbs heat, flexes, and ultimately breaks. This rarely happens during a single use but is typically stretched over a long time and multiple uses, depending on the regularity and tensile stress applied to the impact driver bit.

Improper usage

Improper usage occurs when impact driver bits are misused or incorrectly fitted to the wrong type of fastener or screw. The head of the impact driver bit is then damaged as a result, because most inexperienced users apply force to remedy the situation instead of fitting the correct bit. This action is better known as bit slips.

For this reason, it is essential to fit the bit to the fastener and make sure you have selected the right size and correct type of bit you are attempting to drive before mounting it to the impact driver and starting the driving action.

Different types of driver bits

There are many different types of bits, and each has its own unique design and purpose.  Below we will delve into both common and uncommon bits and discuss what they are used for in general. All of the bits discussed will fit on an impact driver and drill. However, as mentioned above, it is rarely a good idea to use them on a regular drill.

  1. Slotted bits consist of a bit that tapers to a flat blade. More commonly known as “flathead” bits. The screws associated with these bits were the most widely used until the 20th century because of their simplistic yet practical nature.  The screws or fasteners in which these bits fit are also the easiest to produce, making them a favorite for low-budget projects.
  2. Phillips bits are the second most common bit in existence, as the screws for these bits came into existence in 1936. The bit is easily identified by the cross-shaped head that tapers to a blunt or sharp end. Sharp-ended bits are usually used for smaller screws with deeper cross-shaped recesses, while blunt-ended bit are typically used on larger screws with shallower cross-shaped recesses. Henry F. Phillips invented them because of the difficulty associated with slotted screws, such as centering, aligning with a surface, and driving with power tools.
  3. Square bits or Robertson bits are exactly what the first name implies, a bit the end in a square head. These bits can end with a rounded or flat tip depending on the fastener or screw. These types of bits and screws are also less likely to strip and were very popular in the 19th and 20th centuries. They are popularly used in carpentry and woodwork because the bit can easily center and fit on the screw without direct visibility. They are also easy to manufacture, and the screws are easily removed and reused.
  4. Hex socket or Hexagonal bits are bits that have the same shape as the collet of an impact driver. The end inserted into screws or fasterners varies in size, depending on the screw size. The types of screws associated with these bits can also be accessed with a tool called an Allen wrench or hex screwdriver. A tamperproof version of these bits is identifiable by the pin at the end of the bit that slots into the corresponding screws’ recess.
  5. Torx or star drive bits end in a flat six-sided star shape. These types of bits increase torque transfer from impact drivers and decrease the chance of cam-out, which occurs when the bit slips from the recess of the corresponding screw or fastener. They were developed in 1967 by a company called Camcar Textron for use in their automotive and electronic industries.

Final Thoughts

Impact drivers can use regular ¼ inch hexagonal bits. However, as mentioned throughout the article, it is highly recommended that one opts for the impact driver-rated bits as they are less likely to cause damage to the fasteners or the impact driver itself.

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