Spline Bits for Rotary Hammer Drill & Demolition

The rotary hammer is quite the useful tool when you want to drill or punch holes in hard materials such as concrete. For cured concrete that needs to have an anchor installed, a hole must be drilled first so the anchor can be attached. The most used bit for this type of project is the spline shank bit.

Spline Drill Bits Core Drill Bits Spline Chisel Bits

Bosch HC4031 Spline Rotary Hammer Bit
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Bosch HC8031 Spline Rotary Hammer Core Bits
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Bosch HS1817 Chisel bits
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The three most commonly used spline bits are, Rotary Hammer Spline Bits, core bits and chisel or chipping bits.

What is a Spline Shank Bit?

Hammer Drill Spline Bits
The name come from the cross-sectional profile of the spline shank itself. This type of shank has 12 teeth that is designed to fit into the spline drive of the hammer drill.

Spine bits used to be a popular choice for rotary hammers and demolition hammers before the SDS bits became more popular.

Parts of a Spline Bit

The bit is made up of four different sections.
Bosch HC4511 1/2-Inch x 8-Inch x 13-Inch Spline Rotary Hammer Bit
Cutting Tip & Head: Both parts work together to break up the concrete itself. The carbide tip is quite hard and durable, allowing to bust up the concrete with ease.

Flute: This is the depression or trough of the bit that allows the dust from the concrete to be removed while the drilling action is taking place.

Land: This is where the spiral portion of the bit, which resembles the crest of a wave, is raised.

Spline Shank: The 12 teeth are designed to fit perfectly into the drill so that no adjustment needs to be made during the drilling or hammering process.

All four sections work together to drill or punch holes in concrete so that anchors can be attached or to meet the needs of the project that requires holes to be placed in concrete.

Spline vs. SDS

What is the difference between SDS Max and Spline?
The main difference between a spline bit and an SDS bit is in the size and profile of the shank. A spline shank with its 12 sprocket design offers more contact area and hence more efficient. On the other hand, an SDS-max bit is easy to use and keep the bit securely locked inside the tool holder, yet allows it to move up and down during the hammering action.

The spline drill bits and chisel bits have different profiles. The sprocket shank is only available for the drill bits where it is important for the rotational motion. The spline chipping bits have a smooth shank. Conversely in case of SDS-plus or SDS-max, both drill and chisel bits have similar shank design.

Pros & Cons of Spline Bits

Of the advantages that spline bits offers, the most important one is the torque provided by the bit itself when placed in the rotary hammer. Because of its shape and design, it allows for maximum torque to be applied. The result is that holes are drilled easier and with less effort on the person operating the device.

You will need to let the bit do the work and not try to push or force a hole with extra effort. Otherwise, you risk cracking or breaking the concrete depending on its thickness.

There really is no downside to the spline bits, apart from their limited uses as drills beyond their design. Since SDS-max is getting more popular, not all stores are carrying the spline bits.

Pros of SDS Bits

From the pure performance aspect, you will hardly notice any difference between a spline bit and an SDS-max bit. The SDS-plus is smaller and cannot match the performance of the spline.

The SDS-max bits are widely available and in many places they are slightly cheaper when compared to spine bits.

Spline Bit Sizes

The spline bits come in several different sizes that are based on the thickness of the concrete itself and the size and depth of the hole that needs to be created. For the most part, the bit sizes are as follows.

  • 3/8” x 10”, 6”, and 12”
  • 7/16” x 12” and 14”
  • ½” x 12”, 18”, 23.5”, 30”, 36”, and 48”
  • 9/16” x 12”, 18”, 23.5”, 24”, 30”, and 42”
  • 5/8” x 6”, 12”, 18”, 24”, 30”
  • 11/16” x 12” and 23.5”
  • 27/32” x 13” and 23.5”
  • 7/8” x 12”, 18” 23.5”, and 36”
  • 1” x 12”, 18”, and 23.5”
  • 1 1/8” x 12”, 18”, 23.5”,
  • ¾” x 12”, 18”, and 23.5”
  • 1 ¼” x 18” and 23.5”
  • 1 3/8” x 18” and 23.5”
  • 1 ½” x 18” and 23.5”

Keep in mind that the usable length of the bit is generally 6-inches shorter. This means you will have to account for this difference when using the bits.