Choosing the right drills and blades

Drilling and cutting efficiently requires the right kind of drill or blade. And, as the range of materials used on domestic and commercial environments increases, correctly matching drills and blades with materials becomes even more important. And that counts for contractors and DIY enthusiasts alike.


Traditionally, drill bits have been made from steel. Soft, low carbon steel bits can only be used when drilling wood. High carbon steel bits are used on wood and metal, but can lose their edge if allowed to overheat.

HSS (high speed steel) bits can be used to drill a wider range of materials, including metal and hardwood, at higher speeds than carbon steel bits. For extra hardness at higher temperatures, HSS variants, cobalt steel alloys are a good choice.

Tungsten carbide (and other carbide) tips are extremely hard and can drill many challenging materials while retaining their edge. Unfortunately, they suffer from brittleness and high cost.

Coatings such as Black Oxide, Titanium nitride, Titanium aluminium nitride and Zirconium nitride applied to drill bits can extend life and provide greater heat resistance.

Diamond powder coatings are perhaps the most useful of all, providing a long-lasting, durable solution to drilling the very hardest of materials.

A diamond drill or hole cutter can generate a lot of heat, so you need to be careful not to allow it to build up or it can damage some finishes and materials. Consequently, some diamond drills are supplied with a water-cooled wet core that supplies a continuous stream of coolant for drilling materials such as flint and limestone aggregate concrete, reinforced concrete and other hard building materials.

A standard dry core diamond drill is more suited to medium and soft bricks, concrete blocks and abrasive concrete products. A tougher, superfast dry core drill will take most building materials in its stride. These include semi-engineering bricks, clay products, clay products and limestone aggregate concrete.


There are many types of saw available, but in this article we're going to look at circular saws.

If you're looking for a good, reliable wood saw, you should consider a tungsten carbide tipped or HSS blade. For more demanding applications, you'll need to consider more advanced blades or you'll suffer tools that simply can't cut the material, or very soon get blunt and/or overheat. Diamond tipping enables manufacturers to offer a range of blades precisely matched to the requirements of cutting some of the hardest materials.

For Ceramic and Stone tiling for walls and floors, (in homes and in commercial environments), look for tile cutting blades. These will bite into these hard surfaces and provide a clean, well-finished hole. And, for other kinds of flooring, such as concrete and asphalt, there are specialised floorsaw blades.

When it comes to cutting building products such as engineering bricks, concrete and clay products a segmented universal/hard diamond blade with cooling holes to disperse some of the heat is an excellent choice. While, if you're cutting natural stone as well, a top-quality superfast blade would be a better choice.

Stepping down from the most difficult of materials, a standard general-purpose diamond blade can easily handle the demands of cutting bricks, slabs, concrete paviors, roof tiles and most concrete products.

Whatever kind of drilling or cutting job you're faced with, it's always best to ensure you're using the best kind of blade or drill. It'll make the job easier, give you a better a finish and also potentially save you money by lasting longer.

Dave Symons is Technical Manager of Hilbor Diamond Tools, whose Spectrum brand is a world leader in diamond drills and cutting blades.

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