Guide written by:
Jeremy, construction site supervisor, Cardiff
Whether you want to cut, trim, polish, or sand, on steel or concrete, your grinder is the ideal tool, provided you attach the right accessory! Grinding discs, cutting discs, blade discs, brushes, drills, diamond discs - let's get it cut down to size!
- Diamond disc
- Bakelite disc
- Sanding disc
- Polishing disc
- Support disc
- Drill bit
Why do I need specific accessories?
As always, to work efficiently and safely you need the right tool. The same goes for grinders! The design of a disc grinder allows you to attach all kinds of discs to deal with any situation. Hurrah!
A grinder is a real multi-purpose tool. It can cut metal and even concrete and sand different materials as well as polishing, deburring, chamfering, drilling... The most important thing is to have the right disc, brush, or bit for the task in hand. To better help you, we'll sort the various accessories according to their intended use.
What are the different types of discs and accessories?
First, be aware that to be effective, the accessory you plan to use must be compatible with your grinder.
There are different models of grinder, principally distinguished by the maximum diameter of disc that they can take. There are four common maximum diameters:
Professional grinders can reach up to 350mm disc diameter.
The bore - the hole in the middle of the disc which allows it to be fixed to the grinder - must be considered when choosing discs. The standard diameter is 22.23mm.
Each diameter corresponds to a maximum speed of rotation. This is why you shouldn't attach discs of unsuitable diameter to your grinder - you'll risk accidents through cracked discs, flying splinters, etc. The same applies to accessories - these must be used in accordance with manufacturers' instructions. Depending on the task, you might use:
- Diamond discs for cutting through hard materials;
- Bakelite discs for routine use;
- Abrasive discs for sanding;
- Semi-rigid discs for grinding non-planar surfaces;
- Brushes for stripping;
- Plates for use with polishing discs;
- Guides for straight and / or repeated cutting;
- Drills for drilling into hard materials.
Which diamond disc for which work context?
Diamond discs are what you would use on masonry. They have the main advantage of being able to cut hard, resistant materials such as concrete, tile, stone etc. Given the variety of such applications, however, there are several types of diamond disc specific to certain uses.
- "Standard" diamond discs: this is entry level for this family of discs. Non-specialized, they will cut any building material with varying levels of ease. The downside is that they wear out quickly and struggle on reinforced or vibrated concrete.
- Diamond discs fornon-reinforced concrete: specific to non-reinforced concretes, they also allow easy cutting of any building material without integral ironwork - breezeblock, tile, brick etc.
- Diamond discs for reinforced concrete: this is the top of the range as regards diamond discs! No building material, reinforced or not, will hold up to them. This is the ideal type of disc on many construction sites because they don't require you to change discs as soon as you encounter iron reinforcement.
- Diamond surfacing discs: specific to dry sanding of concrete and surfacing of excess formwork or old concrete. These are very resistant, but be careful because they're not intended for cutting.
- Diamond discs for tile: very similar to discs for unreinforced concrete, these are specialized to cut cleanly without producing chips, allowing precise and rapid cutting of any type of tiling. Use on other materials damages these discs very quickly.
What are the uses of bakelite discs?
Bakelite is the classic cutting disc. There are however several different types, depending on intended use and the material to be cut.
- Universal bakelite discs: allow cutting of any non-metallic materials - soft stone, paving slabs, tiles, bricks etc. Although less effective than diamond discs, they're also much cheaper. They wear out quickly and heat up a lot.
- Metal-cuttingdiscs: for clean, precise cutting of structural metal components - tube, sheet, or aluminum section. Their lifespan is long because they wear slowly.
- Stainless steel discs: specific for use on stainless steel due to their tougher composition.
- Metal deburring discs: softer than cutting discs, they allow trimming, facing and deburring of all steel and alloy surfaces.
What's the use of abrasive flap discs?
For tasks such as polishing, sanding or deburring metals, plastics and wooden fittings, abrasive flap discs are designed for finishing. Depending on the task, choose a suitable grain size - the bigger the grain size, the more material removed.
If you want to remove a large amount of material, orient your choice towards ceramic grain discs - for their high abrasive power. Conversely, if you want to polish a delicate surface - bodywork for example - choose a disc with felt or wool flaps.
Abrasive flap discs
What about semi-rigid abrasive discs?
The main advantage of this type of disc is that they're not entirely rigid and can therefore be deformed under pressure applied to the grinder without breaking. They are specifically designed for use on non-planar (e.g. curved) surfaces.
As with any abrasive, depending on the surface in question - concrete, metal, wood, or plastic - you have to choose the right grain.
Obviously, you use the edge of the disc - it's not a case of sanding with the central nut!...
Why go for a brush?
To clean or strip a surface inaccessible to a conventional disc - corners, narrow openings etc. - you'll need to attach a brush to your grinder. Ideal for removing rust and paint, tidying up welding seams and buffing metals, brushes are very specific, fragile, and can be expensive. They should therefore be used correctly. And of course, they also come in several varieties!...
- Steel wire brushes: for stripping and heavy-duty cleaning.
- Brass wire brushes: specific to cleaning surfaces without causing corrosion.
- Stainlesssteel wire brushes: for stripping and cleaning of stainless steel and non-ferrous metals.
- Nylon wire brushes: for cleaning and stripping of hard non-metallic materials - stone, brick etc.
What are the advantages of support discs?
Used as a support for accessories such as fibre discs and felt or lambswool polishing discs, support discs are often made of nylon so that they can be slightly deformed during use.
They are therefore suitable for use on non-planar surfaces and are themselves a wear part just like the discs already discussed. Their key qualities are flexibility and adaptability.
Why install a grinder guide?
Designed to adapt your grinder for stationary use for precision and / or repeated cutting, the commonly available guides are compatible with 125 and 230mm grinders. Their base has a workbench attachment system and a vice to allow clamping of the piece to be cut.
Using a guide enhances operating safety when grinding - and for those who have difficulty following the cutting line, they provide a particularly helpful alternative! Much like with a bench saw, you lower a lever to cut.
And you can even get grinder drills?
Less well-known to the general public, these use adaptable diamond drill bits. They look just like normal drill bits and have the same use, only the tool you mount them on changes.
A certain level of dexterity and a good grip are required to keep the drill line straight. A drill however remains more suitable for drilling tasks in general; exerting the necessary force against the drilling surface can be difficult due to the configuration of a grinder.
If you've forgotten your drill but not your bit, remember it's not the end of the world!
Some final advice before I go ahead and buy?
Accidents are common when using a grinder! Work safely, always using the appropriate disc for the task. Always protectyoureyes with a pair of protective glasses or a visor, your hands with a pair of gloves, and your lungs with a mask!
Pay attention to recoil! For those who aren't familiar, when you go in for a cut from the wrong angle, the grinder can pull away from the material you're cutting... If your dexterity lets you down, you're in for an accident!
To avoid losing your disc key, go ahead and attach it to the grinder cable! Either way, it can generally be replaced as a spare part, just like the disc nut.
As regards bore diameter, you can get hold of converter rings to adapt discs to different grinder bores.
Take care, and happy grinding!
Read more about grinders
To find out more about grinders, follow our editors' advice and check out their other guides:
- How to choose your protective eyewear?
- How to choose your safety shoes?
Guide written by:
Jeremy, construction site supervisor, Cardiff, 128 guides
Electrician by trade, I first worked in industrial estates where I installed, wired and fixed a large number of electrical installations. After this, I managed a team of electricians for this type of work. 10 years or so ago, I turned to building and construction. From the modest family home, to gyms and theatres; I have been able to coordinate, audit and organise all sorts of construction sites. for 4 years now, I am restaoring and bulding an extrension to a bungalow in the heart of the welsh countyside. My experience in manual work and my knowledge means I am proud to be of service. Terraces, interior design, roofing, plumbing, electricty, anything goes! We have, my wife, daughter and I, built almost everything we have from scratch! So to answer all of your questions, and to orientate and advise you on coosing your tools? Easy!