Ever wondered how an SDS drill works, why it's so effective and what the different types mean?
- 1 Why ‘SDS’?
- 2 Understanding the Design
- 3 Outer Parts
- 4 Inner parts
- 5 Drill bit parts
- 6 How does the drill work?
- 7 Pros
- 8 Cons
- 9 Technical Specifications
- 10 Accessories
- 11 Modes of an SDS drill
- 12 What are the different types of SDS drill?
- 13 Frequently Asked Questions
- 14 Conclusion
You may have heard of the SDS drill, or even seen it in action. But what is it exactly? And how does it work?
Whether a newbie or a frequent user of this tool read through our detailed study and learn some of the untold aspects of the SDS drill.
From its German roots, SDS translates – insert, twist and stay, which has been adapted to the wider market as the Slotted Drive System or Slotted Drive Shaft. Alternatively, you could also use the international, custom-made name from Bosch, the Special Direct System.
This implies that a special bit is inserted into the chuck of the drill through the shaft, locks easily and is fitted into a suitable angle. As we shall see moving forward, this and many more features distinguish the SDS drill from other drills.
Understanding the Design
The SDS drill features two handles; one stationary handle at the back, and an extra front handle that is adjustable in any direction. This enhances stability and reduces any chances of creating misaligned holes. Thanks to its sleek hand-gun design, the SDS drill ensures safety while working and provides optimal results.
The power and speed buttons are easily accessible from the stationary handle, so you won’t have to strain. The outer body is made of plastic to make it lighter, while the drilling parts are metallic. It also features adjustable brush plates on the side to enable forward or reverse rotation. This is mainly used when a drill bit is stuck, or when performing heavy screw driving with a small hammer.
To understand how it works, let’s first break down all the parts of the SDS drill and their core functions.
The quick release chuck
This is a special type of clamp, used to insert, hold and remove the drill bit. Just like in the cordless screwdriver, the quick release chuck on the SDS drill is located on the front-most part. It is also known as a keyless chuck, meaning it doesn’t have a chuck key to tighten or loosen the jaws when placing and removing bits.
As seen earlier, the speed control button is located beneath the main handle, where the ring and middle fingers rest. There is also a small lever on top of the main handle to help you navigate through the three featured modes; normal drilling, hammer action, and rotary with hammer action.
It also features a thin metal rod that is adjacent to the drill bit. By sliding it down and placing it in position, you can set the depth of any hole you want to make.
Smooth ball bearings
For any tool that has a rapid internal movement, there has to be something to moderate friction, as well as enabling linear or rotational movement. The SDS drill has two small ball bearings inside it that roll continuously as the piston thrusts the drill bit back and forth rapidly.
When using the hammer mode to drill into stone or concrete, the SDS drill has an inbuilt hammer mechanism that works by using a hammering kind of movement to drill into the material. This tells you just how diverse the SDS drill can be.
This is a short metal that slides up and down/ back and forth inside the cylinder of the drill to impart motion to the drill bit. Think of it as the engine of the whole drill. It uses the pneumatic mechanism, meaning it transmits and controls energy by using compressed air.
Drill bit parts
We all know what a drill bit is, the metallic part that does the actual drilling and comes in different forms/shapes. The SDS drill has its own special kind of bits that comprise of four main parts;
This is the part that goes into the drill through the chuck. It contains two small slots that hold it to the drill and two extended grooves that are responsible for fitting the whole drill bit into position. Unlike the SDS shank, normal bits are smooth and don’t have the extended grooves.
Compared to the shank, the land is slim and is spiral in a spiral nature. It resembles the crest of a wave and is quite easy to spot.
As you approach the tip of the drill bit, you will find the flute, which is a spiral and resembles the trough of a wave. It has a small hole that ensures concrete dust is disposed of effectively.
Lastly, we have one of the most important parts in the bit; the tip, which is part of the head. It is brazed using Carbide metal to harden it, hence making it easier to break through any hard surfaces.
How does the drill work?
The SDS drill is designated to drill into concrete, brick or block work mainly to;
- Create a path for plumbing or installing wiring
- Install fastenings
Unlike other drills which only turn, the SDS turns and also reciprocates, making it suitable for breaking hard surfaces. That’s not all, the hammer action and drilling force is driven directly to the end of the bit, and not on the chuck like other drills. In essence, it does twice the work of a normal drill.
After installing the drill bit through the keyless chuck and adjusting the front handle, the tool should be ready to jump into action. Ensure that the power source (mains or battery) is well connected and that the drill responds to the on/off button.
Pressing the speed trigger enables the piston to move the drill bit up and down rapidly, marking the beginning of the actual drilling. By increasing the speed, the compressed air within the drill propels the piston faster and thrusts the drill bit more rapidly. It is important to note that the grooves in the drill bit are locked firmly despite the fast moving motor, making it impossible for the bit to slip and fall off.
Aside from that, compatibility is key when it comes to this drill. Standard drill bits cannot be used with the SDS keyless chuck. Therefore, when you need to use standard bits on the SDS drill, it is recommended to use the standard chuck to avoid damaging any part. To change a chuck, simply twist and unscrew it from its place, click the preferred standard chuck to the drill and fasten it till it holds firmly. Typically, I would use a regular combi drill in this instance instead.
Afterwards, the bit should be disengaged by pulling down the chuck, twisting the drill bit, and pulling it out.
- Features a high drilling rate and chiselling performance
- Has an overload clutch to protect the machine and the user
- Offers a versatile range of modes
- Compact design and suitable for overhead work
- The power supply can either be mains or battery powered
- LED light in some drills for easy working in dark rooms.
- Not compatible with normal drill bits
- Costly, compared to regular drills
SDS drills come in cordless or mains powered variant. Due to this, technical specifications may differ, as seen below;
Power and Speed
Corded SDS drills have a voltage of 110 or 240 Volts and a good cable length for efficient drilling. Depending on the brand, cost and specification, the wattage can range significantly, ensuring that the drill bites into any concrete or brick easily. From a work output point of view, they can drill a 4-inch-deep and ¾ inch wide hole in about 30 seconds, producing 2.5-3.5 joules of impact energy.
On the other hand, cordless SDS drills use lithium batteries with a typical voltage of 18V, although some 36v models are now on the market. Being a powerful drill I would recommend you use a high Ah battery to get the best running time from your drill. Regardless, they can match the performance of the corded variants.
Speed is a great factor to consider in any power tool. It is measured in revolutions per minute(rpm), which is the number of turns per minute. The SDS drill has an outstanding range of 920-1300 rpm, implying that it runs at 40 mph- 60 mph when put into perspective. A fast cordless screwdriver operates at a speed of 200 rpm, so you can tell how fast the SDS tool is. Anything above 1000 rpm is capable to drill any piece of concrete or steel.
Size and Weight
SDS drills come in different size and weight options, you can get a really lightweight option, but my personal preference is something on the heavier side that you can get behind. This isn’t an indication of the performance of the tool. They are typically a similar size to each other, fairly large compared to the standard combi drill.
The drill bits also come in different lengths and diameters. Lengths can range up to 36 inches.
Noise and Vibration
On normal drilling mode, you should expect a rating of 95 dB(A), and when using the hammer mode, the noise increases slightly to 100 dB(A). To give you a more accurate idea, the ordinary dishwasher produces 80 dB(A), while a power lawn mower gives away 90 dB(A).
Going by this, it is safe to conclude that the SDS drill is a noisy tool. The drill has an average vibration level of 11m/s2, which is quite respectable for such a powerful machine.
We would always recommend safety products when using power tools, we have listed some of these below. But in the case of the noise omitted from an SDS drill I would definitely recommend ear defenders.
Whilst the SDS drill is a fantastic bit of kit, you have to buy most accessories for yourself. After purchasing, you will only receive the carrying case, depth gauge, mains cable (if corded), and front handle. Most people are unaware that there are extra accessories to make the best out of this handy tool, apart from the bits, chisels, and batteries (if cordless).
Drill bits and chisels
You would need a couple of drill bits and chisels to work on different surfaces effectively. In most cases, users buy drill bit sets that contain a variety of chisels and bits. They come in different sizes, and most of them are silver in nature. Some drill bit sets have up to 246 pieces of assorted bits and chisels.
The fact that you should have ear defenders and appropriate safety glasses on when using such a powerful tool is a no-brainer. It would be wise to invest in protective gear, for your sake, and also to improve performance. Other than the glasses and ear defenders, you would also need some safety work gloves, and a dust mask is always useful.
The box cutter could save you the hassle of using the hammer drill and chisel to curve a box-shape out of a wall. With a rectangular/square shape, the cutter can be inserted into the drill bit and used to create a symmetrical box shape within no time.
Cable guide drill bit
When drilling into block or brick walls, a cable can be used to guide the drill bit. It is threaded through the hole in the tip of the drill bit or the shank, and then it is pulled or pushed through the cavity created.
This is a kind of chisel that is combined with cranked shafts and cutting edges to drill through a wall when creating channels for conduit installation. At 30 mm wide, the chisel is effective when doing any pipework or electrical installation.
Scutch comb holder
Special bits known as scotch combs can be used in an SDS drill during the process of plastering a wall. In most cases, this whole process of rendering is done manually, but this tool makes it much easier.
The residual current device is a safety master plug that is used to monitor power supply for corded appliances. In case of an earth-current fault when drilling in wet areas, or during a power surge, the RCD cuts off the power supply to the drill, preventing electric shock and protecting the power plug. We recommend all SDS users have this adapter in their tool bag.
Modes of an SDS drill
Every SDS drill has a button used to transition into three different modes;
Normal drilling mode
The normal mode is recognized by most if not all drill users and is also referred to as the rotary mode. The chuck rotates the drill bit round and round as it breaks into the desired surface. The normal drilling mode is used mainly when working on light materials such as wood, hence very little force is needed.
Hammer only mode
When demolishing hard surfaces or using a chisel, the rotary motion is turned off, and the hammer-only action is enabled. This explains its substitute name, the rotary stop. Through the hammer mechanism inside the drill, the piston pounds directly at the back of the bit/chisel, with no assistance from the chuck. At great speeds, this mode is simply a weapon of destruction.
Rotary with Hammer mode
The rotary with hammer mode is one of the main reasons why the SDS drill outshines most of its counterparts. Most drills don’t have this combination and it is quite effective when drilling. As said earlier, the SDS drill bit uses rotary action and hammering at the same time to deliver twice the results of a normal drill.
There is a fourth but uncommon mode that is right between the rotary with hammer and hammer only modes. It is a lock mode that is mostly used when chiselling, to enable users to move the gearbox and set the chisel in any position, then set it back to hammer-only mode. The chiselling function is used when removing materials such as tiles or performing any light breaking.
In most SDS drills, you can unmount the keyless chuck and use a standard chuck when using standard drills. Even so, the three modes will still function correctly.
What are the different types of SDS drill?
One of the most common misconceptions about the SDS drill is that the design differs in different drills, but this is not the case. What defines the different types of drills is the kind of drill bits and chuck systems used. Based on this, we have three main SDS drill types; SDS and SDS plus, SDS max, and Spline. They all have their fair share of capabilities as observed below;
SDS and SDS Plus
These two types are usually categorized together because their drill bits are completely compatible with each other, hence used interchangeably. The two shanks have the same grooves and same diameters of 10 mm.
Nonetheless, the SDS plus has an added advantage just as the name suggests. It has four indentations at the end (two close, and two open-ended) allowing it to hold the shank more firmly than the SDS drill.
Similar to the SDS plus, the SDS Max has improved connectivity, but has an additional indentation, making them a total of five indentations (two close-ended and three open-ended). It has a diameter of 18 mm and uses carbide tips like the rest.
Currently, it has the tightest shank and creates a better grip when drilling into bigger diameter holes. It is the overall best system for heavy concrete and masonry drilling. No wonder most demolition tools use SDS max bits and chisels.
The Spline Shank system is like an older version of the SDS Max and is used for heavy drilling workloads. Its shank has 12 teeth, also known as ‘splines’ which fit into its special chuck system, and is held by a retaining pin. More to that, the shanks are a perfect fit since they are held to a specific tolerance.
It still has many users, despite being an older version, and prides itself on offering a maximum drilling torque. The spline has a diameter of 19 mm and has a wide range of bits used for chipping, chiselling, cutting, bushing and digging.
Frequently Asked Questions
Which is the Best SDS drill to buy?
Many people end up wasting money on huge, powerful drills, while a smaller less powerful drill would suffice. Understanding your needs should be the first course of action, as it will guide you to the SDS drill you need, rather than the one you want.
Based on your environment, you should be able to establish whether you need a cordless or corded drill. If your interests revolve around light concrete drilling and chiselling old tiles, then a normal SDS drill would be enough for you. If you have grander plans, the SDS Max and SDS plus would be a great option for heavy drilling and creating large diameter holes.
Another factor is how much you would be willing to spend on a drill. There are cheaper alternatives that have great performance. We recommend SDS drills from Bosch, Makita, and DeWalt because of the great quality associated with these brands.
Who should use the SDS drill?
The drill is used for heavy concrete and masonry work, so any mason, plumber, electrician, building contractor or DIY enthusiast could make use of one. That being said, using the SDS drill for basic DIY tasks such as making small holes is like taking a gun to a sword fight.
However, if you are into electrical installations, making sophisticated modifications around the house and doing some extensive roofing, then you would definitely need to add this tool to your collection.
How to maintain and increase the lifespan of an SDS drill?
Buying an SDS drill is one thing, maintaining it is another. Here are a few noteworthy tips and precautions to help you maintain your drill for a decade or more;
- Use the front handle to increase stability, it’s designed to help you distribute the weight properly and protect the flute from being destroyed.
- On rotary and hammer mode/hammer mode only, avoid leaning on the drill or pushing the drill harder as it could spoil the bit.
- When the drill bit has reached its maximum depth, you should never try to drill deeper. This could spoil the shank, flute, and the carbide plate.
- An SDS drill can only use standard bits when there is a standard chuck in place.
- Before drilling, always confirm there are no wires lying around. Drilling into electrical cables can be dangerous.
- Most SDS drills come with a 2 to 3-year warranty; make use of it in case of functionality issues.
- Check for wear and tear frequently, especially in the drill bits, which are the only consumables in the product.
As far as power drills are concerned, the SDS drill is one of the best options you will get on the market by far. As we have seen, it is multitalented, features state-of-the-art drill bits and chisels, and has a powerful hammer mechanism.
Its unique aspects such as the forward and reverse actions as well as high drilling speeds make it a great contender, and a must-have tool for any masonry or concrete exercise.