The most common power tool for tradesmen, construction workers and DIYers alike is probably the drill. Drills come in many sizes and strengths and can be used in various different ways, from driving small screws to cutting much larger holes with a holesaw. Appropriate substrate materials differ greatly too, as there is a drill out there for cutting everything from wood to tiles, metal and masonry. However, it is important to always use the right machine and accessory for the task at hand, otherwise you are at risk of serious injury. One type of drill is the SDS drill. There are three main classifications of SDS machine – SDS Plus, SDS Top and SDS Max – each with different measurements and ideal applications.
The abbreviation “SDS” originally comes from the German “steck, dreh, sitzt (insert, twist, fits)” but now stands for “Spannen durch System (Clamping System)” in German speaking countries and “Special Direct System” internationally. It is a type of drill bit clamping system developed by Bosch in the 1970s for use with hammer drills, and it is generally used for heavy duty jobs hammer drilling jobs where extra power is required.
The drill bit shanks have several grooves up and down their length that allow the bit to be clamped but also allow a sliding movement of the bit inside the chuck. With a regular hammer drill the whole chuck has to be moved to create the hammer action, but one advantage of an SDS machine is that as the bit moves backwards and forwards inside the chuck it adds to the hammer action. This means that the bit can be hammered much harder, which makes drilling through tough materials much easier with much less force required. Another advantage of SDS machines is the speed at which you can change bits; you simply push the bit into the chuck and it locks automatically. Removing a bit is just as easy – simply pull the release ring or push a button to disengage the locking mechanism!
As mentioned above, there are several main types of SDS machine and bit. Each of these types of SDS machine has their own chuck and shank design, and are not compatible with one another.
These bits have a 10mm shank with two open grooves held by driving wedges, and two closed grooves held by locking balls. SDS-Plus hammers are the most common SDS machine, and are generally up to 4kg.
These machines are uncommon. SDS-Top bit shanks have a 14 mm shank similar to SDS-Plus, and are designed for hammers from 2 to 5 kg. This is the most uncommon SDS type.
These bits have an 18 mm shank with three open grooves and locking segments rather than balls. SDS-Max is generally used for hammers over 5 kg.
Another advantage of SDS machines is that high-spec models often have 3 modes: rotation only, hammer drilling, and chiselling. This means that, with the right bit (e.g. masonry bit, pointed chisel), they fulfil a variety of functions from simple wood drilling tasks through to demolition of concrete and drilling through the toughest of housebricks. These tougher tasks are even easier with a more heavy duty tool such as an SDS Max breaker.
The only potential downside to SDS machines is their increased costs. The machines themselves often cost a lot more than similar non-SDS machines, and the accessory range is not only smaller but also more expensive (although you can buy a chuck adaptor and still use normal drill bits for non-SDS applications). However, if you spend a lot of time drilling through masonry and concrete these disadvantages are certainly outweighed by how much quicker you get the task done and the increased power, efficiency and durability of SDS-Plus, SDS-Top and SDS-Max drills.