What's the Difference Between an Impact Drill and a Rotary Hammer?

Those who deal with professional construction work, or perhaps need to do activities at home with some frequency, know well that there is a substantial difference between a hammer drill and a rotary hammer. We anticipate the answer: the first, namely the hammer drill, is a tool for drilling all materials that however has the ability to activate the movement to drill building materials.

It works well, although in some cases it can struggle to proceed. The rotary hammer, on the other hand, is specialized in drilling concrete, reinforced concrete, stone and solid bricks: it has no limits on this front. Is that enough to conclude the chapter on the difference between hammer drill and rotary hammer? Not quite, here are some clarifications that will help you during the purchase phase.

What is the difference, in summary?

The difference between these two tools is hidden in the technology used. The hammer drill is a tool designed to drill materials like wood, metal and stone by exploiting a mechanical vibration generated by the friction of toothed discs.

In contrast, the rotary hammer is a specialized machine that uses a pneumatic piston to generate high-energy strikes. The tool in question is designed to optimally drill reinforced concrete and stone. Furthermore, you have the ability to chisel and excavate, activities denied to the common drill and which bring the rotary hammer closer to the classic pneumatic hammer.

The Hammer Drill, a Definition

Let's provide some clear information about these tools. The hammer drill, for example, is a tool that is indispensable in workshops but also in homes: it is the power tool that allows you to drill both with rotary motion and with percussion. That is, a perpendicular movement of the bit that precisely strikes, hammers the surface that we are trying to drill.

This option is fundamental for drilling stone, walls, bricks and concrete. It is used only in these cases, it is forbidden for drilling metal, plastic or any other material like ceramic or porcelain stoneware: it would be a total disaster. So, the peculiarity of the hammer drill is the ability to combine the rotation of the bit with a striking movement to scratch stone materials.

On its side it has great versatility, a quality model can help you in all household chores and also in the professional field it has its functionality. On the other hand, it cannot be defined as a tool suitable for demolitions and drilling operations on all building materials: if you need to make important holes in a reinforced concrete block, you risk ending up with a burned motor and unusable bits.

The Rotary Hammer, What is it and What is it for?

Let's go to the opposite side, that of the rotary hammer or anchor hammer. It is a tool similar to a drill but larger and more robust, certainly heavier and harder to handle. But this imposing nature is linked to the fact that its structure is designed to contain and express superior force. The difference, however, is not only in power but in the technology behind it.

In fact, inside the rotary hammer there are no discs but a real piston driven by compressed air. The motor compresses the air, which then fires a striker against the bit. You will notice that the strike is much drier and slower than the drill, but much more powerful and automatic. In fact, with this tool you must not push or you will suffocate the air cushion and work worse.

This tool can only work with rotation to drill with rotation and percussion mode to also act on the toughest building materials. If you use only percussion the bit no longer rotates. The rotary hammer (so called because it is used to install large anchors) becomes a small demolition hammer. It serves to strip plaster or detach bricks.

The rotary hammer is essential when you need to make holes in concrete or beams, remove old bathroom or kitchen tiles and run channels in the wall for electrical installations. From here we can understand the differences between hammer drill and rotary hammer.

So, What Difference Regarding the Bits?

Just as there are differences between rotary hammer and hammer drill, we also have divergences in the bits used. From the point of view of the shank, the rotary hammer does not use smooth bits but a special attachment called SDS-Plus (or SDS-Max).

This system allows the bit to slide back and forth freely, transmitting all the strike energy to the surface without the bit slipping in the chuck. The bit itself is also very different: for drill models, the hard metal plate that cuts into the building material block is two-edged and has a simpler arrow shape. It is a solution designed to scratch the material quickly thanks to the high rotation speed. The bits for rotary hammers are perfect for drilling reinforced concrete.

The head is more massive, the body has 4 cutting edges in a cross shape instead of 2. This serves to shatter the material instead of scratching it and to prevent the bit from getting stuck when it encounters the iron rod of the reinforced concrete (two-edged bits often get stuck).

Can I use a normal bit on the rotary hammer? Only if you buy an adapter (a classic chuck that fits onto the SDS attachment). In that case, however, you absolutely must turn off the percussion, otherwise you'll destroy the chuck and the bit in seconds.