Whenever there was a need to cut, shape, grind, or remove excess materials from wood, metal, or stone, chances are you used rotary burrs at the end of a die grinder. The combo is versatile, fast, and effective at what it does and is seen in dozens of professions and industries, from tooling and precision engineering, welding, general wood and metalworking, and everyday DIY and hobbyist projects where quick stock material removal is required.
The same tool bits are also seen at dentists, jewellers, and sculpting studios, albeit in different sizes and shapes.
What Are Rotary Burr Cutters, and Where Are They Used?
Regardless of the name they go by, whether rotary burrs, burr cutters, carbide burrs, or die grinder bits, these are essentially the same and refer to the tool bits that are fitted in rotary tools and used for cutting, smoothing, grinding, shaping, carving, and deburring purposes in a range of materials.
They see the most action in die grinders, but smaller ones are also used with dentistry and jeweller drills, dremels, pencil grinders, and any small or large rotary tool that can reach high RPMs. A well-made burr cutter is strong enough to go through even the most stubborn materials, and the bits come in different shapes and sizes, meaning a range of cuts.
What Are They Made Of?
These pieces are made of tungsten carbide, an alloy containing equal amounts of tungsten and carbon, and are tough, durable, and long-lasting. Compared to ordinary High-Speed Steel (HSS) bits, the material can sustain extremely high temperatures when working in very hard materials, such as ferrous metals, ceramics, or stone, and do this consistently for much longer.
The alloy is over three times as strong as steel, has the highest compressive rate of any known metal, and has extremely high rates of impact and abrasion resistance. Only synthetic and natural diamonds are stronger.
There’s additional strength in the hardened alloy steel that makes up the shank. These qualities result in shorter work times, higher operating precision with cleaner, smoother finishes, and bits that are geared for years of torture even in the hardest tasks.
Common Applications
The insane hardness of tungsten carbide means a burr cutter can be used almost anywhere. Carbide burrs make easy work of even the hardest ferrous metals, such as cast iron or high-grade steel.
They also work wonders and are very precise when working with softer non-ferrous and precious metals, ranging from aluminium and copper, their alloys (6061, 7075, brass, and bronze, respectively), as well as gold, silver, and platinum. And common metals found in everyday and industrial uses like zinc, nickel, and titanium.
Besides metals, burr cutters can shape hard and soft plastics, all types of wood, ceramics, tiles and harder masonry. The wide scope of materials also entails they are practical additions in dozens of professions: toolmakers, smash repairers, welders, carpenters, woodworkers, dentists, jewellers and anywhere there’s the need for a tool attachment that get precise cuts and finishes in the least amount of time.
Types, Shapes and Buying Considerations
Single vs. Double Cutting Profiles
These bits come with either a single or double-cutting profile, with the first good for fast stock material removal, general milling and deburring purposes, and smoothing or cleaning tasks in rougher workpieces.
Burrs with two intersecting cutting flutes (also called Aluminium cut) offer better precision and smoother finished surfaces when used in light to medium material removal, as well as in lighter milling, deburring and cleaning tasks. These also are easier to use, especially in softer metals, plastics and wood, and produce smaller chips.
Though rarer, there are also burrs with multiple cutting profiles in a design known as a diamond cut.
Shapes
To get the desired result in the workpiece, you’ll have to consider the wide array of shapes the bits come in. More common shapes are ball burrs when you need to deburr and enlarge holes, curved slots, and curved metal.
Tree variants are used for sharper workpiece angles, cylinder when smoothing surfaces and working with tight right angles, and countersink in either 60 or 90-degree cones when countersinking, bevelling and general boring. Other common shapes are oval and flame for precise, rounded edges, and tapered variants to access hard-to-reach areas.
Though the differences may only be slight, the shape the rotary cutter comes in will determine speed, precision, and of course the result. When you need versatility across various types of workpieces, go with packaged sets that consist of several bits in varying shapes. They come out as a lot cheaper too than when purchased separately.
Sizes
While shape will largely determine where and how the bits are used, size additionally impacts the tools burrs work with. This relates to both the overall diameter of the cutting heads, as well as that of the shank and which secures the bit to the rotary tool.
Diameters range between 1/8 to 1 inch or 3 to 25mm in the cutting head while shanks come in diameters from a tiny 1.6mm in burrs used in dentistry or engraving, to 16mm in heavy-duty and industrial uses. Shanks can also be in the standard lengths, or offered in extra-long varieties when working in tight spaces.
Manufacturers also state the recommended speeds at which differently sized burrs can safely and efficiently be used. Smaller types, such as those fitted to dremels and pendant drills operate at very high speeds reaching over 35,000 RPMs, whereas bigger variants used in die grinders top out at around 12,000 RPMS.
Using Carbide Burrs
Before use, check if the burr is tight in the collet or chuck and that your workpiece is clamped, preferably in a vice on a workbench. To get the cleanest results and the smoothest finishes, ensure that you use the burrs at the recommended speeds while applying light pressure to the workpiece.
This prevents jabbing and damaging the material or chipping in the burr itself. It advised ending work with an upstroke. Use protective eyewear at all times.
Summing Up
If you what to grind, cut, carve, sand, polish, and get rid of sharp edges and imperfections in any type of workpiece, then your best bet is using a carbide burr and the appropriate rotary tool.
Rotary burrs are tough, easily eat into the material you’re working with, and get work done in the least time and with no fuss. And they produce neat and clean results worthy of any pro. Choose burrs based on shape and size for your project, or invest in packaged combos if you need more versatility across a range of jobs.