Can I use an SDS bit in a normal drill, or a normal bit in an SDS?

The two systems solve different problems. An ordinary chuck grips a smooth shank by friction and transmits rotation. An SDS holder does not grip at all — it lets the bit slide back and forth while a striker hammers the end of it, which is the only way to deliver serious blow energy into masonry. The diagram shows both shanks side by side, and the difference explains everything about what will and will not adapt.

Step by step

1. Understand the SDS shank.Two closed grooves that locking balls drop into so the bit cannot fall out, and two open slots that driving ribs engage to turn it. The bit deliberately rattles a few millimetres in the holder. That movement is the mechanism, not wear.
2. Understand why an ordinary chuck cannot hold it.Three jaws closing on a shank with slots cut along it have very little to bite on, and the shank is hardened. It will slip under load, chew the jaw faces and can be thrown out of the tool.
3. Fit round-shank bits to an SDS with a chuck adaptor.An SDS-shanked keyless or keyed chuck that clicks into the tool holder like any other SDS accessory. Twist bits, wood bits and driver bits then work normally.
4. Switch the hammer off before using an adaptor.Set the tool to rotary only. Percussion through a chuck adaptor pounds the adaptor apart, transmits nothing useful to the bit, and shakes the workpiece.
5. Accept the accuracy penalty.A chuck adaptor stacks tolerances — the adaptor moves in the holder, the chuck holds the bit — so a long bit visibly wobbles. It is fine for rough holes and poor for anything that needs to be accurate.
6. Do not use it as a screwdriver.SDS drills usually have no torque clutch and their low gear has enormous torque. Driving screws through an adaptor strips heads and snaps screws immediately.
7. Buy SDS bits for masonry, not adaptors.If you own an SDS, use SDS masonry bits. Putting a round-shank masonry bit in an adaptor throws away the entire reason to own the tool, because the blow cannot reach the bit.
8. Know when it is the wrong tool entirely.An SDS with an adaptor is a heavy, clutchless, slightly wobbly drill. For woodwork and assembly, use a drill driver. The adaptor is for the moment you are up a ladder with one tool and one job.

Tips

• SDS-plus and SDS-max are different sizes and do not interchange. Domestic tools are SDS-plus, and adaptors are sold for each.
• Some SDS drills come with a removable chuck that swaps for the SDS holder rather than plugging into it. That gives a much better-running chuck than an adaptor, and it is worth checking whether yours has one.
• A quick-change SDS bit holder for hex driver bits is a different accessory again, and useful if you routinely put screws in after drilling with the same tool.

Common mistakes

• Clamping an SDS bit in a keyless chuck to save buying an adaptor — It slips under load, destroys the jaw faces, and the bit can be ejected. There is no version of this that works.
• Leaving hammer action on with a chuck adaptor fitted — The percussion has nowhere useful to go, so it destroys the adaptor and rattles everything else.

Questions people ask