Rotary Burrs 101: Everything You Need to Know

What do toolmakers, welders, dentists and jewellers all have in common? They all use the same cutting tool bits. Maybe not in the same tools, but largely to the same effect. These practical and tough tool attachments are readily deployed when there’s the need to grind, cut, shape, smooth or remove excess materials. They’re handy in dozens of professions and also work wonders in almost every DIY job around the house. 

The Basics of Rotary Burrs

Tool bits used to remove slag in welds, machine elaborate metal parts or do away with unsightly rust go by different names but are essentially the same. Whether it’s rotary burrs, burr cutters or die grinder bits, they fit in the receiving end of the many rotary tools found in as many applications. The bits are made of some of the toughest compounds out there and make easy work of wood, stone, metal, plastic, tiles, ceramics, teeth, bone…you name it. They can be found in different shapes and sizes to ensure users get precise cuts in the least amount of time. 

What They’re Made of

Compared to ordinary high-speed steel (HSS) bits you’d use with a regular drill, a rotary burr tool is made of tungsten carbide, one of the hardest and most durable materials readily available. It’s ideal for cutting through materials of varying hardness and does this for longer without being affected by the high temperatures that chip away at ordinary bits. 

The material also allows for varying operating speeds, either at lower RPMs for precision work or higher speeds in quick stock removal. Being three times as strong as alloyed steels, and with the highest compressive strength of any known metal (only synthetic and natural diamonds are harder), carbide burrs ensure consistent results. extremely low wear and tool bits guaranteed to last. 

Where Carbide Burrs Are Used

The favourable properties when compared to all other tool bits mean carbide burrs are seen in shaping, cutting, grinding and removing a range of different materials. This means ferrous metals such as cast iron and items in varying steel grades, as well as common non-ferrous metals like aluminium, copper, zinc and nickel. Precious metals like gold, silver and platinum in jewellery, or bronze and brass in decorative items are also simple to shape.

It’s not just metals. Burr cutters can work both hard and soft plastics, all types of wood, stone, concrete, brick and other masonry, as well as harder ceramics. Industries that use carbide include metal and woodworking, carpentry and joinery, tool machining, welding, plumbing, auto and smash repairs, construction and more. Here burrs are usually attached to the business end of an appropriately-sized die grinder. Smaller bits are used in smaller rotary tools, like dremels and engravers and used in dentistry, jewellery making, and sculpting works of art. 

Types, Shapes, Sizes and What to Look for When Buying

Choosing a quality rotary burr tool can get complicated considering the wide range on offer. Varieties differ in terms of cutting profiles, shapes, sizes and additional features like shaft lengths. 

Differences in Cutting Profiles

Burrs can have either a single or double-cutting profile. These extend from the tip of the bit to the shaft. Single-profile burrs are preferred for stock material removal and faster speeds, as well as general milling and deburring, or when smoothing rougher surfaces, such as advanced rust. Double-cut types have two intersecting flutes (cutting profiles). 

The design promises more precision in smoother surfaces but is also handy in light to medium material removal, light deburring and milling and cleaning tasks. Besides precision, these tool bits also are more forgiving and preferred in softer metals, especially aluminium, softwoods and plastics. For especially hard materials and substrates, look to diamond-tipped burrs in either single or double-cutting profiles. 

Wide Range of Shapes 

The wide array of shapes burrs come in means they can be used almost anywhere. This also guarantees different types of cuts as well as consistent results. Ball burrs are the most common, and are usually the go-to type when you need to deburr and enlarge holes, hollow out material, or create concave or curved inserts. 

Tree burrs are used for getting sharper-angled cuts or when rounding off edges. Cylindrical burrs are ideal for right angles, and in general smoothing tasks, and countersinking varieties are used in countersinking and flush finishes as well as bevelling and general boring. Rounded edges can be achieved with oval and flame burrs, while taper-edge types, often with longer shafts are good for hard-to-reach places. 

If you’re having a hard time picking exactly what’s right, or need rotary burrs for multiple purposes, then packaged sets with different shapes make the most sense. They’ll also be easier on the wallet than purchasing each type separately. 

Size Matters

Sizes determine which tools the burrs work with. Most are intended to be used with die grinders and have diameters ranging between 3 and 25mm or 1/8 to 1 inch when sourcing imperial bits. Smaller burrs of 1 to 2mm are seen in dentistry work and when engraving jewellery. Shank sizes and lengths also impact your work and the bits you choose. There are standardly sized shanks suitable in most cases, and extra-long variants to get to out-of-reach areas. 

Diameters and sizes, specifically in the shanks also affect tool speeds. Smaller dentistry bits can rotate up to 500 thousand times a minute, while larger general-purpose burrs used with die grinders often work best between 8 to 12 thousand RPMs. In between, you’ll see drummers and engravers turning burrs at 35000 times a minute. 

General Use and Maintenance Tips

Burr shanks must be attached tightly in the tool collet and with the workpiece clamped or secured in a vice, tool operators apply low pressure downwards. It is recommended to start with slower RPMs and work your way up to prevent jabbing, chipping or outright damage to what you’re working on or to the burr itself. 

While lubricants aren’t needed in burrs made of tungsten carbide, diamond burrs may require water or lubricant to prevent chipping. To make work cleaner, always end with an upstroke. Needless to say, deburred chips can cause harm so wear protective gear, specifically goggles, each time. 

After use, ensure that you remove chips stuck in the cutting profiles. This is done with a wire brush. You can get burrs to last longer by storing them separately and keeping them away from dust, heat, oil and water.