When you are shopping for hammer drills or power chisels, you are going to come across the term SDS when looking at the features of the hammer drill. This is a critical feature as it will determine the type of drill bits that you can use with the drill. To avoid making mistakes with compatibility between different bits, you need to make sure you know what you are about the purchase.

What Does SDS Mean?

SDS stands for “Slotted Drive Shaft“. This describes the unique indents that you will see along the shaft of the bit that goes into the chuck of the drill.

Are SDS Plus and SDS Max The Same Thing?

The answer is a firm no. They are very similar and the names are admittedly quite confusing. Plus seems to suggest that it is bigger than normal SDS and then Max also suggests bigger, but what is bigger and why are they named this way?

I cant explain much behind the naming but Max is going to be the biggest of the two. This means that if you have an SDS max drill, you will need an adaptor to use the smaller SDS plus bits.

• SDS Plus = 10mm
• SDS Max = 18mm

SDS Max bits have a shaft thickness that is almost double that of SDS plus. As you can guess, SDS max bits are not going to fit into an SDS Plus drill. The video below will give you a comprehensive explanation of the differences between the bits with lots of information and images about the different types of bits and fittings they use.