What makes a wood drill bit so different from a masonry bit? And why is it so important to use the right type of wall anchors? We’ve put together some tips on choosing the best drill bits and anchors for any task – so you can avoid breaking any more drills and can make sure your shelves stay firmly on the wall.
1. Choosing the right drill bit
The type of drill you need depends on several factors: the type of material you’re drilling, the type of hole you want to make, and the size of the hole (depth and diameter).
1.1 What type of material are you drilling?
Generally speaking, drills can be divided up into metal drills, wood drills, masonry/concrete drills and multi-purpose ones. Most drill bits have a spiral shape – which helps to remove the drilled material from the hole.
1.1.1 The right drill bit for metal or aluminium
To prevent the tip of the drill from wearing out (drilling at too high a speed or with too much pressure may cause it to turn blue), try using drilling fluid or cutting oil. You could also remove the drill from the hole at regular intervals, to allow it to cool down slightly.
1.1.2 The right drill bit for wood
Soft or hardwood, chipboard, plywood or MDF panels – for all these types of wood, you’re best off using a This has a centring point that enables you to position the drill precisely. Furthermore, tapered drill bits help to avoid ripping up the wood.
1.1.3 The right drill bit for stone or concrete
1.1.4 The right drill bit for tiles
For drilling soft to medium-density tiles, you can use a special with a diamond-ground carbide tip. To prevent the drill from slipping off the surface, try sticking some tape to the tiles first and then drilling the hole. Some advice: start on a low speed setting and then gradually increase it as the drill bores deeper into the material. To avoid cracking your tiles, it’s important to apply the right amount of pressure. Apply moderate pressure to begin drilling the hole, then light to very light pressure as you proceed.
1.1.5 The right drill bit for plastic and various other materials (e.g. wood and metal)
can be used to drill into plastic and a range of other materials – making them ideal for drilling cabinet doors, for example, which consist not only of wood, but may also feature metal elements/fixtures. They are suitable for use on all materials that you’re likely to work on in the home, including multi-layer materials, bricks, tiles and aluminium. However, where possible, it’s always better to use the special drill bit for a specific type of material than the MultiConstruction bit – because these are developed especially for the material in question.
1.2 Choosing the right-sized drill bit
The diameter of the drill bit you choose will depend on how big a hole you want to drill. Most drill bits nowadays have diameters of between 1 mm and 20 mm.
You can also determine the size of the drill bit based on the screws you want to use. The diameter of the hole you drill should be slightly smaller than the diameter of the screw. So, for example, if you’re using a 3.5 mm screw, use a drill bit with a diameter of 3 mm.
If you're using wall anchors as well as screws, the drill bit and anchors should have the same diameter.
The diameter of the drill bit and the material you want to use it on will also determine the drill speed.
- Small drill bit diameter: high speed
- Large drill bit diameter: low speed
- Soft material: high speed
- Hard material: low speed
The drill speed may need to be adjusted depending on the combination of material and drill bit diameter.
1.3 Drill packaging
When you go to the DIY store, you need to know which material you’re drilling, and what diameter and length drill you need: an image like the one above shows you what you can use the drill for. The diameter of the bit can usually be found in a box in the top-left corner, whilst the total and working length can be seen on the tape measure along the edge of the packaging.
1.4 Types of drilling and drill length
Sometimes you need to drill special types of holes or drill into unusual materials. Whatever your need, there’s a drill bit for the occasion.
1.4.1 Through holes
If you need to drill all the way through a material, you need to make a through hole – a good example of this is our If you’re making a through hole, the drill bit should be longer than the thickness of the material.
1.4.2 Blind holes
Sometimes you don’t want to drill all the way through a material – for example, if you want to make invisible holes for hanging things up, as with our project. This is called a blind hole. It’s easy to make one in wood using a wood twist drill that is shorter than the thickness of the material. If you only have one drill bit that is longer than the material thickness, you can mark up the depth of the hole on the drill with tape. That way, you’ll know how far down to drill. If you need a drill with a bigger diameter, the is your best option.
1.4.3 Deep holes
Deep holes are similar to blind holes, except here the holes are particularly deep (at least five times deeper than the drill diameter). It’s the most common type of drilling if you want to mount something on the ceiling or wall. To give an example, you’ll need to drill deep holes to so that you can hang your project on the wall.
1.4.4 Drilling different-sized holes
You can use a to quickly and precisely drill holes in non-ferrous metals, sheet steel and plastics. Thanks to the different diameters on the bit, you can drill holes ranging from 4–20 mm. A centring aid helps you to drill accurately.
1.4.5 Drilling very large holes in wood
If you want to drill holes with a particularly large diameter (i.e. greater than 10 mm) in wood – which are also called blind holes – it’s best to use a Forstner bit. However, this is not suitable for particularly deep holes or through holes.
2. Determine the depth of the hole
Not sure how deep to drill into a wall? Then base the depth on the wall anchors you want to use. As a rule of thumb, use the following formula to determine the depth of the hole: anchor length + 10 mm. This will ensure the anchor is completely out of sight later on.
If you're not using anchors, use the length and diameter of your screws to determine the drill bit length and the hole depth and diameter.
3. Which drill bit goes with which tool?
In addition to the various tips, drill bits also differ in terms of their shank shape. The shank is the part that is inserted into the drill chuck.
The different types of drill chucks include a self-centring/three-jaw chuck, which holds the drill bit in place with three "jaws" (points of attachment). By turning the chuck, it can be adapted to the diameter of the drill shank to firmly secure the bit. There are also various SDS chucks: here the drill bit snaps into place when it's inserted into the chuck, with no need to tighten the chuck or size it to the diameter of the drill shank.
There are four main types of drill shanks, each of which is suitable for specific tools:
- A round shank or cylindrical shank fits in almost all drills and impact drills.
- A hexagonal shank. Drill bits with this shank fit better in drills with three-jaw chucks. The hex shank is a special type of this shank and has an additional groove. As well as three-jaw chucks, it fits in SDS Quick and hex shank chucks.
- SDS Quick drill shanks fit in the Uneo cordless hammer drill and can also be used with all three-jaw chucks. This makes it the only shank that can be used with both a hammer drill and an impact drill.
- SDS Plus shanks are for use exclusively with SDS Plus drill chucks. These shanks cannot be used with other chucks such as the three-jaw chuck or other SDS chuck adapters.
We have created a table to help you decide which drill bit is right for your tool.
4. What is the right kind of wall anchor for my project?
To ensure pictures and shelves remain firmly on the wall, it’s important you use the right wall anchors. And the same rule applies as for drill bits: the anchor must be a good match for the material you’re drilling into.
The size of the anchor you need will depend on the size of the hole you’re drilling. For example, if you used a 6 mm drill bit, you should use the same size anchor. The screws you use should then have a slightly smaller diameter of around 4–5 mm, which is opposite to if you're not using anchors (see 1.2). The wall anchor packaging will usually specify the length and diameter of the screws you should use.
In general, a screw should always be slightly longer than the anchor to ensure it protrudes out from the wall. The longer an anchor is, the greater the load it can bear. So, the higher the load, the longer a screw should be in comparison to the anchor. Depending on the load, the screw can be between 3 mm (low load) and 16 mm (high load) longer.
4.1 Different wall materials
Walls can be made from concrete, brick or panels such as plasterboard (drywall).
4.1.1 Standard or lightweight concrete
Concrete is an ideal material for fixing or hanging items onto. Long wall anchors made from plastic and chemical solutions such as grout, with the right equipment, are especially suitable for this type of wall. For lightweight concrete, which is lighter than standard concrete thanks to the addition of Styropor or pumice, are ideal. These expand as the screw is tightened, ensuring they are firmly anchored in the wall.
4.1.2 Brickwork (solid brick)
For walls made from solid brick (e.g. sand lime or clay bricks), almost all plastic anchors can be used.
4.1.3 Brickwork (perforated brick)
If your walls are made from perforated brick (similar to solid brick, but with evenly spaced cavities), you should try to use anchors that bridge the cavities or fill them in. Anchors with grout are ideal, as are plastic anchors that expand.
4.1.4 Panels (e.g. plasterboard)
For walls made from plasterboard, also known as drywall, you can use a special spiral-shaped drywall anchor made from metal or plastic. Unlike standard anchors, this does not expand. You should also use hollow wall anchors made from plastic or metal.
4.1.5 Hollow walls
For the best results with drywalls, you should use either a drywall anchor or a special hollow wall anchor made from plastic and metal. This is suitable for use with cavities of different sizes and holds securely. A universal anchor is also an option, as it expands behind panels and cavities.
If your wall is very soft and thin, it may help to make the hole you drill one millimetre smaller than the anchor – this ensures it sits even more firmly in the wall.
Bosch does not accept any responsibility for the instructions stored here. Bosch would also like to point out that you follow these instructions at your own risk. For your own safety, please take all the necessary precautions.