Beginners guide to drill bits

So many different drill bits - What do they all do?

When it comes time to make a hole in something tougher than card, your drill bit becomes important, and one of the things that I am always amazed at is how long it took for someone to explain the differences to me. So I’m going to run through the main drill bits you’ll likely find here in order to save you this pain.

Standard “twist” drill

This is what everyone thinks of when they think of drill bits, however this little section hides a multitude of tricks. A twist drill can come in an HSS (High Speed Steel) version or not - the non HSS drill is only useful on wood or similar “soft” materials and not that common these days. The HSS bits can be used on metal as well as wood and are generally preferable to own as they are more versatile. HSS drill bits often come with coatings of titanium nitride which is a gold colour or with a Tungsten Carbide tip and these bits tend to be tougher than straight HSS bits. Cobalt steel is another type of material used in twist drills and is better for drilling really hard materials like cast iron, stainless steel or titanium. These drill bits will mostly have a stamp telling you what they are made from.

Lip and Spur drill bit (Wood drills)

Apparently these are better for wood because they don't wander due to the point and they clear the waste better- I cant say I have ever had issues using a twist drill in wood and I would normally use a centre punch before drilling so the drill bit wandering is not an issue. I generally never use these but apparently they are good for making dowelling pockets?

Glass and tile drill bits

These are the ones that look like tiny arrows or spears and they are normally coated in a super hard material like carbide or diamond. As this bit actually grinds away the material you are drilling into they have the capability to generate a lot of heat. In a material that does not conduct heat well like glass or tile this can cause it to shatter from localised expansion due to heat. It's important to drill these bits slowly and try to use a cooling lubricant like water or kerosene to cool the bit and the work area. Don't push too hard either and it goes without saying do not use the hammer function on the drill if it has one.

Masonry Bits

This is a masonry bit, as its name suggests its designed for brick, mortar, blocks etc, it's also very effective on plaster although it can wander a little. These bits are primarily used in a "combi" drill which is a drill that has a hammer function, this is normally indicated by a graphic of a hammer that needs to be selected via a rotating collar or a switch somewhere on the drill body. Selecting the correct drilling mode is important as it is the combination of the rotation and the back and forth hammer action that breaks down the masonry and makes the hole.

SDS Bits

For when you absolutely positively have to drill through every single wall in the room! This is like a monster version of the masonry bit, however it needs to be paired with a specialist drill. SDS Drills have a much more pronounced back and forward action than a "combi" and so make much more of the hammering action, SDS “Drills” don't actually have to drill at all and often are fitted with chisels or points and are used as smaller hand held jack hammers, The one we have here is a drill bit however and you can see both the aggressive blades at the tip for breaking away the wall and the fluting at the base that marks it out as an SDS bit, they allow the drill to be rotated with force while also moving back and forth.

Different materials dill in different ways think of things like stone, glass, ceramic, brick, wood, metal etc. Once you start thinking of the characteristics of these materials its obvious one drill bit wont work on them all! Hopefully I have gone some way towards clearing up this subject for you.

Malcolm B
18 Mar 2025