Not all drill bits are alike. For decades, standard drill bits had to be tightened and retightened into the drill using a chuck key. But the SDS drill changed the design to create a more secure connection.
What is an SDS Drill?
Generally, a rotary hammer drill or roto hammer is called an SDS drill. Standing for Slotted Drive System, an SDS drill bit has slots along the shank. This means when it is placed in the drill, it creates a stronger connection which results in less tightening when being used.
The SDS tool holder has two distinct advantages when compared to regular hammer drills with 3 jaw chucks.
- The slotted drive ensures that the drill bit doesn’t slip inside the chuck.
- The slots allow the drill bit to move forward and back during the hammering action.
Developed by Bosch and Hilti back in the 1970s, the original SDS drill was a mainstay until being replaced by the updated SDS Plus. Bosch calls this Special Direct System (SDS) or Spannen durch System in German. The SDS Max offers a modified profile that makes it perfect for bigger drills.
The primary use of SDS drill is for punching through tough material. They are designed mostly for construction, renovation, and demolition work that standard drills do not have the heft or power to do. SDS drills accomplish this by a combination of rotation and hammering, where the drill bit moves back and forth to punch through.
How Do SDS Drills Work?
You simply place the shank of the SDS bit into the SDS holder, rotate it slightly to align the slots until you can push the bit in. Once the shank goes inside, the spring-loaded chuck will secure it without the need for additional tightening. It speeds up the process of drilling because less time is spent tightening and then retightening when the drill is being used.
SDS drill shanks are especially well suited for masonry drill that hammer into concrete and stone. This is because the drill can move back and forth inside the chuck in the same manner as a piston. All this while the drill is still held securely so that it doesn’t fall out or loosen when rotated.
Are SDS Drills Hammering Drills?
No, they are not. While similar in main functions, the hammering action that is delivered is different. This is because with hammer drills the entire chuck is moved back and forth as opposed to just the drill bit in case of an SDS rotary hammer. The result is that hammering drills are not as efficient and disperse the impact of each stroke. While better compared to a standard drill for use with hard materials, a hammering drill is not as good as an SDS drill.
In addition, SDS drills are not percussion drills, either. Again, the difference is subtle, but important as a percussion drill use geared disks which are used against each other. The result is that the entire chuck moves back and forth in a hammering action. Less effective and precise than an SDS drill, but can be useful in certain situations.
SDS Drill Bit
The reason why it stays secure during rotation is that the cross-section of the shank matches the chuck itself. Instead of being round or smooth, it has a pattern that matches the chuck. Plus, the slots allow for vertical movement during hammering operations, but it does not allow the drill to slip out.
It is a complicated process as the drill combines rotation with backward and forward movement. But it is easy to understand the system itself of how the bit stays in the drill. The result is that an SDS drill can punch through harder materials faster and with more precision. This makes it perfect for construction when holes need to be created to pass wiring, conduits, or other materials.
Plus, it can be used for renovations when materials need to be removed and replaced. While most demolition jobs do not require the precision of the SDS drill, it is still quite useful as a powerful, hand-held drill to place holes in walls for explosives or to hook lines which will pull down walls, ceilings, and the like.
There are three variations of SDS drill bits.
- SDS Plus
- SDS Max
While all the three options have similar functions, the SDS max is not interchangeable with the other two versions due to differences in size and shank profile.
SDS vs. SDS Plus vs. SDS Max
The differences between all three are subtle but important. Even if all three terms are used for the same purpose, knowing the difference can help avoid mistakes being made about which type to take.
|SDS & SDS Plus||SDS Max|
|Drill Size||5/32” to 1 1/8-inches
(≈ 4mm to 28mm)
|½” to 2-inches
(≈ 12.5mm to 50mm)
|Profile||Symmetric. (2 closes slots and 2 open grooves)||3 Open grooves and 2 closed slots.|
|PowerTool||SDS and SDS plus rotary hammers||SDS Max Roto hammers, Jackhammers and demolition hammers.|
|Uses||Light Duty Applications
SDS and SDS+
Put simply, the SDS Plus has essentially replaced the standard SDS drill. While you may still find plenty of SDS drills around, the SDS+ represents an overall improvement in the drill system. In addition, they are newer and available on the general market. You can purchase older SDS drills through secondary markets, but they do not offer any real advantage apart from nostalgia.
The SDS Max is, as the name implies, are larger and have more indentations in them for a better grip on the bit.
You usually find SDS Max drills used for commercial work, such as the construction, renovation, or demolition of larger buildings. They are also used for residential work, but you will mostly find them in the hands of professionals.
This means that if you are thinking of purchasing a masonry drill, the SDS+ is probably the best. Unless you are an independent contractor hired to build or tear down large buildings, the SDS Plus is arguably the best version available for most needs.
What are SDS drill bits used for?
They are primarily used when a hammering action is needed to break through harder materials. For example, wood is a soft material that allows the drill to easily pass through. But masonry is much harder and tougher for a standard power drill to punch a hole. The result is usually wasting your time, breaking the drill bit, or having a hole that is not deep enough to be of any use.
The drill can create a more precise hole compared to other devices that can cut through hard materials such as concrete or masonry. For construction purposes, the holes can be used to hold bolts or anchors that support conduit and other materials. For demolition purposes, the holes created can be used to attach chains or ropes to pull down a wall. Or, to place explosives if it is a large building that needs to be torn down.
In addition, the hammering action can be turned off if you need to drill a precise hole through softer materials. This avoids the need to carry around multiple drills when working with different materials.
Can I use an SDS drill bit in a normal drill?
The answer is you can, but there will be some issues. This is because the shape of the SDS and SDS+ are not suited for standard chucks. A standard 3 jaw chuck grips the drill differently compared to chucks designed for hammer drills.
The result is that the shaft of the SDS drill bit may seem tight at first, but it will work itself loose faster than drills designed for standard chucks. It may also affect the SDS drill itself, causing the edges and sides to be marred or bent so they are less useful in the hammer drill chucks.
Can I use standard drill bits in SDS drill?
You should not use a normal drill bit in an SDS drill. The regular bit with a round shank does not have the right shape to properly fit into the chuck. Plus, they are not designed for the hammering action that will quickly wear down the bit.
Remember that the SDS chuck has spring-loaded balls that engage into the slot to hold the bit.
There are adaptors or SDS chucks on the market, but you may be better off simply purchasing the proper drill for the chuck. That is a cheaper and easier to remember option compared to attaching and detaching an adaptor, even if they are not that expensive to purchase. If you do decide to use a standard drill bit in an SDS drill, then you should use the adaptor and be sure to turn the hammering action off. Otherwise, you might need a new drill bit pretty soon.
Can I use SDS max in SDS plus drill and vice versa?
You cannot use them interchangeably since the shank profiles are different. You can, however, get SDS plus to SDS max adaptor to use your existing tool.
Overall, the SDS, SDS plus, and SDS Max drills have their uses and are still found in construction, renovation, and demolition work where hammer drills are common.
Back to Contents
- What is an SDS Drill?
- How Do SDS Drills Work?
- SDS Drill Bit
- SDS vs. SDS Plus vs. SDS Max