A drill bit shank are the part of the drill bit that sits inside the tool chuck. The shape of the drill bit shanks determines how the drill bit transfer torque and resists slipping from the chuck. Different job require different drill bit shank shapes to provide an apropriate level of support for hammering and rotation.
Using the wrong drill bit shank may cause the drill bit to spin uselessly inside the tool or fail to proper seat into the chuck. Round shanks is smooth shank cylinders commonly used in standard drills. The round shank will seat between three jaw of the chuck.
Types of Drill Bit Shanks and How to Use Them
Round shanks are smooth, so they are used with twist bits to drill into wood and metal. A hex shank has six flat sides and is specifically design to lock into the quick-release collars of an impact driver tool. Because of the flat sides, the impact driver cannot spin the hex shank when it deliver blows to the shank.
This makes it appropriate for tasks that require high torque to drive deck screw and lag bolts. SDS drill bit shanks is designed for masonry work. The shank has groove that allow the drill bit to move forward when the drill bit hammer pound it.
SDS Plus shanks are used for residential and commercial property for most general work. The diameter of the SDS Plus shank will fit into most rotary hammer. SDS Max shanks has a larger diameter than SDS Plus shanks.
SDS Max shanks are used for larger core bit for reinforced slabs. The SDS Max shank has more mass and slots to prevent twisting. Do not force an SDS shank of one type into a chuck of another design because the diameters and slots does not match.
A Morse taper is a cone-shape drill bit shank used in drill presses and lathes. The Morse taper will seat into a spindle and create friction to keep the drill bit from slipping. The Morse taper has a small tang on the drill bit shank.
A drift key can allow a drift key to remove the drill bit. A reduced shank is a drill bit shank with a smaller diameter at the area where it grip the chuck. This allows bits with an oversized shank to fit into a standard chuck.
Other shapes of drill bit shanks exist for other tool task. A triangle shank is a shape that will lock in position in an older chuck to stop the drill bit from rotating when the round shank begin to slip. A spline shank is used for heavy demolition hammer that require high torque.
A threaded shank will screw directly into holder on industrial machines. Some bit also have quick-change collars with ball detents so that a user can change a drill bit with one hand. Before selecting drill bits for a tool, you must first identify the type of chuck it has.
Keyed chucks will provide a strong grip on round and reduced shanked bit. Keyed chucks require a separate key to open the chuck to insert a bit. Keyless chucks allow for much faster change in drill bits.
Keyless chucks can work with round and hex shanks. SDS chucks are constructed to allow SDS bits to move axially. They are not constructed to clamp onto smooth drill bit shanks.
Once you have identified the type of chuck, the material being drilled into must also be considered. Wood can take most round and hex shanks. Metal also take round and tapered shanks.
For masonry work, SDS drill are the only tools that will deliver the high impact necessary. Some mistake are made when people do not follow the drill bit shank categories. One of the most common is to use a round shank in an impact driver tool.
The round shank will spin within the impact driver when it hammer into the workpiece. Another mistake is to force an SDS shank into a standard chuck. The SDS shank will neither seat properly into the chuck nor will it remain steady in its position.
Another mistake is to not sufficiently tighten a keyed chuck. The bit will walk across the workpiece rather than cutting it. Lastly, attempting to remove a Morse taper bit by hand without using a drift key will score the spindle seat where the bit enter and ruins the fit.
To maintain drill bit shanks properly, wipe the drill bit shanks clean before inserting it into the chuck. This prevent grit from wearing the jaws of the chuck. For SDS bits, apply a single drop of oil into the grooves of the shank once a month to prevent corrosion.
Store drill bits in an index case so that the shanks will not hit each other. If drill bit shanks do hit each other, the impacts may dent the tapers on the shanks or dull the cutting edge on twist bits. By ensuring that the shank of a drill bit matches the chuck and the material to be drilled, the bit will seat into the chuck perfectly and the chuck will tighten properly on the shank.
