What is the SDS system?

What does SDS mean?

This is a common question asked by a DIY newbie. To make matters worse, there are three types of these exercises available: SDS Plus, SDS Top, and SDS Max. This article provides a basic background on what the SDS system is, where it originated, and what part of the system might interest you.

Origins of the SDS system

Bosch invented the SDS drilling system in 1975. Bosch advertises SDS internationally as a special direct system, although in German-speaking countries it is more commonly known as the Spannen Durch system (meaning “clamping system”).

Chuck types available

There are three standards available:

  • SDS Plus is the smallest of the three and is a very common accessory for professional and DIY use. The shank of the tool is 10mm and inserts 40mm into the chuck. It is rated for hammers up to 4 kg.
  • SDS Top is the least common of the three standards. It uses a 14mm accessory that inserts 70mm into the chuck. SDS Top is rated for hammers in the 2kg to 5kg range.
  • SDS Max is a very common industrial accessory. SDS Max employs an 18mm shank with three open slots and a locking mechanism, instead of the two rolling balls used in the SDS Plus and SDS Top. The shank inserts 90 mm into the chuck. Max is rated for hammers over 5kg and is a common accessory for light industrial use.

How does SDS work?

All SDS tools have a cylindrical shank with several grooves on the sides. In the SDS Plus and SDS Top bits there are small grooves to provide rotational force and two closed channels for a ball roller to fit. The ball roller allows the bit to move back and forth freely while under the action of the hammer. SDS Max employs three ball rollers.

SDS Plus tools are installed by pressing the chuck back into the body of the bit and inserting the bit. The extraction is carried out in a similar way. SDS chucks are keyless.

Advantages of SDS

  • Quick tool change
  • No chuck key required for tool exchange
  • Improved hammer action compared to normal varieties.
  • Rotation stop or hammer only action allows versatile use

Disadvantages of SDS

  • The cost of tools is higher than normal accessories
  • Chuck requires regular lubrication
  • The chuck must be kept clean internally, otherwise damage may occur

In conclusion

The SDS system gives modern power tools a versatile advantage over older competitors. SDS tools are generally more powerful than their conventional cousins. Although the bits used in the system are more expensive, durable and long-lasting, typically a tungsten carbide (TC) tip or similar material is applied to extend service life.

SDS Plus is a very common accessory for electric drills used by professionals and DIY enthusiasts alike. SDS Top is a rare fit and this may or may not be a problem for your purchase choice. SDS Max is usually a light industrial accessory only, as it is used with hammers of more than 5 kg. Hammers of this classification are typically used for light demolition work.

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