What are Burrs?
Carbide Rotary Burrs, often referred to as rotary files or die grinder bits are used for cutting, shaping, and grinding, and for the removal of sharp edges, burrs and excess material (deburring).
Helpful notes: For drilling holes in hard metals you would need to use carbide micro drills or carbide straight shank drills. For cutting slots, routing, profiling, contouring, counter-boring, and reaming you would use a a carbide end mill, carbide slot drill or a carbide router. For cutting and shaping stone or glass you would use a Diamond Burr.
1. Carbide Burrs Can be Used on Many Materials
Die grinder bits can be used on a multitude of materials: metals including steel, aluminum and cast iron, all types of wood, acrylics, fibreglass and plastics. Carbide burrs are also perfect for working on softer metals such as gold, platinum and silver as they last a long time with no chipping or breaking.
- Steel, Carbon Steel & Stainless Steel
- Cast Iron
- Gold, Platinum & Silver
- Plastic, Carbon Fiber Reinforced Plastic (CRP), Glass Fibre Reinforced Plastic (GRP)
- Brass, Copper & Bronze
Different cuts of carbide burrs are best suited to certain materials, see the next point below to find out about the different cuts.
What Do You Use Carbide Burrs (Die Grinder Bits) In?
Yes, the clue is in the title...Ideally carbide burrs are used in Air Tools i.e Die Grinders, Pneumatic rotary tools and high speed engravers. Micro Motors, Pendant Drills, Flexible Shafts, and hobby rotary tools such as a Dremel.
Helpful note: Always use a handpiece that runs true (with no wobble)
Who Uses Carbide Burrs?
Carbide burrs are widely used for metalwork, tool making, engineering, model engineering, wood carving, jewellery making, welding, chamferring, casting, deburring, grinding, cylinder head porting and sculpting.
They are used in the aerospace, automotive, dental, metal sculpting, and metal smith industries; to name but a few.
2. Carbide Burrs Commonly Come in Two Cuts; Single Cut and Double Cut (Diamond Cut)
Single cut (one flute) carbide burrs have a right handed (Up cut) spiral flute. These tend to be used with stainless steel, hardened steel, copper, cast iron, and ferrous metals and will remove material quickly. Use for heavy stock removal, milling, deburring and cleaning.
- Heavy removal of material
- Creates long chips
Double cut carbide burrs tend to be used on ferrous and non ferrous metals, aluminium, soft steel and also for all non-metal materials such as plastics and wood. They have more cutting edges and will remove material faster. These are the most popular cut and will see you through most applications.
Double cut are sometimes referred to as Diamond Cut or Cross Cut (2 flutes cut across each other) . They will leave a smoother finish than single cut due to producing smaller chips as they cut away the material. Use for medium-light stock removal, deburring, finishing and cleaning.
- Medium- light removal of material
- Fine finishing
- Smooth finish
- Creates small chips
The below image indicates the double cut, single cut and again, the double cut or diamond cut.
Shank sizes of your carbide burrs:
The shank is the mount of your burr that fits into your rotary tool, die grinder, micro motor etc; so to make it clear, it is the opposite end to the working part of the tool. These are usually found in the following shank sizes:
- 1.6mm or 1/16"
- 2.35mm or 3/32"
- 3mm or 1/8"
- 6mm or 1/4"
3. The Various Shapes of Carbide Burrs and How To Use Them
Making a decision on what shape to use will depend on the profile or cut you are looking to achieve.
These different shaped burs will get into many a nook and cranny and produce some interesting profiles.
Carbide Ball Burrs
Use a ball or spherical shaped carbide burr to create concave cuts in your material or to shape and hollow out an area. Small carbide ball burrs from as tiny as 0.5mm in diameter are ideal for intricate carving projects. Many wood carvers, stone carvers and metal engravers use these carbide carving burrs in a hobby drill, micro motor or a high speed handpiece. As we mentioned before, make sure to use a handpiece that runs true i.e with no wobble.
Carbide Tree Burrs
Use for rounding off edges and making concave cuts. Use the pointed end for cutting in hard to reach areas and acute angled contours.
Carbide Inverted Cone Burrs
Use inverted cone shaped tungsten carbide burrs for making v-cuts and rear side chamfering.
Carbide Pointed Cone & Carbide Round Nose or Ball Nose Burrs
Good for rounded edges and surface finishing in difficult to reach areas or tight and narrow angles and contours. The round nose or ball nose cone are often referred to as a taper shape.
Cylinder Burrs. Round Nose/Ball nose/End Cut
Choose from an end cut cylinder (with a cutting edge on the end) for contour finishing. Cylinder without end cut (flat on the end and no cutting edge) for contour finishing and right angled corners or a round nose or ball nose shape which is a cylinder shaped carbide burr but with a rounded head.
A wheel shaped burr with a smooth top, round edges and fluted sides. Great for channel work and shaping.
Choose from 60 degree or 90 degree angle countersink burs, sometimes referred to carbide cone burrs. These are ideal for beveling, counter-boring, chamfering and for getting into acute angled areas of your work.
Carbide Burr Set
Small carving projects with intricate detailing often require multiple burrs of different shapes, this is when a carbide burr set comes in handy.
"I love the smaller version and range of points in this carbide burr set. I work on Whitby Jet which is 3-4 on the Moh hardness scale. The material is a natural organic fossil and does have the occasional inclusion of other minerals in it. These can be calcite grains (called spar) or flecks of pyrites both of which are much harder than the Jet. This is where the benefits of the sharpness of the cut and the lovely variety of points in these carbide burrs works well" - Hal Redvers-Jones. The Whitby Jet Heritage Centre.
4. What Speed or RPM should you use your Carbide Burrs?
The speed at which you use your carbide burr in your rotary tool or die grinder will depend on the material you're using it on and the contour being produced, but it's safe to say you do not need to exceed speeds of 35,000 RPM. The table below shows some approximate speeds.
Helpful note: If the burs are chipping easily this could be due to the speed being too slow. However, it's ideal to start the cutting slow, increasing the speed as you go along. High speeds will prevent clogging in the flutes of your burrs.
|Diameter of Burr||RPM|
|1.6mm or 1/16"||25,000 - 35,000|
|2.35mm or 3/32"||17,000 - 26,000|
|3mm or 1/8"||17,000 - 26,000|
|6mm or 1/4"||11,000 - 16,500|
|12mm or 1/2"||8,000 - 12,000|
|16mm or 5/8"||7,650 - 11,500|
5. Do Not Apply Too Much Pressure
As with all drill bits and burrs, let the burr do the work and apply only a little pressure otherwise the cutting edges of the flutes will chip away or become smooth too quickly, reducing the life of your burr.
6. Carbide Burrs are Harder than HSS Burrs
Good quality Carbide Burrs are machine ground from a specially chosen grade of carbide. Due to the extreme hardness of the Tungsten Carbide they can be used on much more demanding jobs than HSS (High Speed Steel).
Carbide Burrs also perform better at higher temperatures than HSS so you can run them hotter, for longer.
HSS burrs will start to soften at higher temperatures so carbide is always a better choice for long term performance.
What Are The Advantages of Tungsten Carbide Burrs?
- Long life
- Use for long production runs
- High stock removal
- Ideal for using on many hard and tough materials
- Ideal for Deburring, finishing, carving, shaping and smoothing welds, moulds, dies and forgings
7. Keep The Carbide Burr On The Move
When using your die grinder bit try not to keep it still for too long as this will prevent the burr from digging and jabbing into your material causing unsightly marks and roughness.
End on an 'up' stroke for a smoother finish to your work.
Helpful note: Using a carbide burr on Soft Cast iron is a great way to de-clog them.
I hope you feel better informed now as to how you should use your carbide burrs, why you should use them and what you should use them on.
Helpful note: Carving Stone
For carving into stone you will need to use Diamond Burrs.
- Always ensure your burr shank is well inserted into your collet and clamped down tightly
- Keep pressure light and keep the bur moving, focusing on the highest material first
- Ensure your work is secured tightly to your work bench
- Don't snag or jam your burr into your work
- Wear eye protection as a minimum, but better still use a full shield for your face