No place that offers burs offers just a few. Dozens and dozens are more the norm. A wide variety of brands, materials, head shapes, and configurations—and each in up to two dozen different sizes. The sheer number can leave an unwary shopper speechless.
Most people would say that they would rather have too many choices than not enough. Inundated by choices every day, some people can stride into a store or scan a catalog (ignoring all potential distractions) and know exactly what they want and buy it, while others (especially me) have every intention of making a quick decision and thirty minutes later end up asking, “Why am I still here?” And to make matters worse, I’ll sometimes spend all that time looking and comparing, and then walk out of the store with nothing in hand. Why?
I recently listened to a presentation on TED by Sheena Iyengar. She is a professor at Columbia Business School and author of The Art of Choosing. Listening to her speech gave me a sense of relief about the state of shillyshally I frequently experience when I shop. I learned from her that I am not the only one who becomes stifled when presented with so many choices.
So let’s tackle that forest of burs and cut them down to size. Burs come in different metals, shapes, and sizes. But which one is best for my job? Let’s take a look at the different metals first.
At first glance, Rio Grande offers many choices in metal type: tungsten, vanadium, tungsten vanadium, carbide, tungsten carbide, high-speed, hardened vanadium, and diamond. Actually, our burs can be separated into four main categories: high-carbon, high-speed steel (HSS), carbide and diamond. All of our burs are high-speed, by the way. ‘High-speed’ in the name simply tells you that, at speed, with the friction and heat that is generated by the work, the bur will maintain its temper. But, keep in mind that some burs will perform better at high speeds and some at low speeds.
Here is a quick and comprehensive list of characteristics of alloyed steel:
- Hardness– the steel’s basic Rockwell scale or the ability of the steel to resist permanent deformation
- Heat Resistance– the steel’s ability to maintain its temper at high temperatures
- Strength– the steel’s ability to resist applied force
- Toughness– the steel’s ability to absorb energy before actually breaking
- Ductility– the steel’s ability to flex or bend without cracking/breaking
- Temperability– the steel’s ability to be hardened or tempered
- Wear Resistance– the steel’s ability to resist abrasion (important when dealing with sharpening)
- Corrosion Resistance– the steel’s resistance to oxidation (rust)
- Edge Retention– the steel’s ability to maintain an edge (not the same thing as wear resistance!)
- Ability to Take an Edge– the ability to put an edge on it (fine-grain steels generally take an edge much better than coarse grain steels)
Depending on the alloy/steel combination, burs will have some of these qualities more than others. While considering the different options, it is helpful to keep in mind that the most expensive bur does not mean that it is going to be the best one. The best bur for the task is going to depend on several factors, which will be explained at the end of this post.
Low-Alloy, High-Carbon Steel
High-carbon steel has more than .8% but less than 2.11% carbon and has high hardness and wear resistance. Carbon is the most important alloying element in steel. Without carbon, steel would not exist.
Carbon combines with other elements to provide hardness and strength. With increasing carbon content, the strength and hardenability of the steel increases (which is great for tools), but other characteristics such as ductility, machinability, formability, and weldability are decreased. High-carbon burs are more prone to rusting and do require some maintenance.
Most of Rio’s high-carbon burs, also known as high-carbon steel burs, are alloyed with small amounts of vanadium, tungsten or both. Each of these elements, even in small amounts, provides you with significant benefits. Tungsten increases hardness at elevated temperatures. Vanadium increases strength, helps prevent metal deformation and improves impact resistance. Generally, when it comes to alloying steel, one must choose between hardness and toughness unless it is alloyed with both vanadium and tungsten. Having both hardness and toughness allows manufacturers to make these burs with more flutes. More flutes allow for more precise cuts to be made. High-carbon steel burs don’t last as long as carbide and HSS burs. But the payoff is that you get very precise cuts and can operate them at lower speeds, which is great for stone setting.
Rio Grande’s Lynx burs and Busch burs are made with a combination vanadium/tungsten alloy. Many of our Dentsply Maillefer burs are made from low-alloy vanadium. Dentsply Maillefer also carries carbide burs (described below).
High Speed Steel (HSS)
High Speed Steel (HSS) is also high-carbon tool steel, containing a large dose of tungsten. A typical HSS composition is: 18% tungsten, 4% Chromium, 1% Vanadium, 0.7% carbon and the rest, Iron. HSS burs maintain temper despite the friction and heat that is generated by the work.
HSS can be heat treated to a very high hardness. This, combined with wear resistant carbides, creates a very good edge retention and abrasion resistance. One limitation of HSS is that its usable cutting speed range is lower when compared to carbide. The advantages of HSS over carbide are its strength to withstand cutting forces and the low cost of the tools. They also require less maintenance than the high-carbon burs since they are less prone to rust. From the tool life point of view, HSS is tougher than carbide and will last a longer time. Rio Grande carries an extensive supply of HSS burs.
Carbide burs are three times stronger than any steel. They are heat and wear resistant.
Tungsten and vanadium increase strength in steel by forming carbides. Other carbide-producing elements include chromium, titanium, niobium, molybdenum and cobalt. In order for a steel to be carbide steel it must contain at least 1% of the carbide-producing element. A carbide tool has an equal number of carbide producing element as carbon atoms.
Carbide burs are great for cutting carbon steel or stainless steel and can be conveniently cleaned with a propane torch. The only downside to this metal is that, due to its high hardness, it is brittle and can chip or shatter more easily than other materials.
Burs made with this material are great for soft metals such as high-karat gold and platinum because they are very strong and precise but unlikely to chip or break on the softer metals. These burs are very durable and as long as they don’t chip will last a long time. They can also be used for longer production runs and cut with much less effort. Carbide burs can be used for deburring, finishing, smoothing, shaping, and carving many types of materials. Carbide slices or chips away at material leaving a smooth surface. But they can still be effective on harder metals. It is best to use these at high speeds with light pressure.
Diamond Plated and Diamond Sintered Burs
Since diamond is the hardest of all known materials, when it is bonded to stainless steel burs, it creates a cutting edge with superior cutting and durability. Diamond burs are either plated or sintered. A plated bur has industrial diamond bonded to its surface; a sintered bur is essentially made with diamond-impregnated metal. As the diamond on the cutting surface wears away, fresh diamond is continually being exposed. It’s easy to see why sintered burs last longer than plated.
Diamond burs are best for grinding, carving, and sculpting—great for stones and glass. They grind away at material and can leave a rough surface that requires some polishing afterward. Diamond burs won’t chip but they do have a shorter lifespan than the carbide burs.
Here are some differences at a glance to keep in mind when deciding which burs to buy:
Which one should you use for your particular material?
Overall, the best metal for the job depends on how much you will use the burs—and on personal preferences such as whether you prefer more durability or more edge. Do you prefer less maintenance? Will they be used intermittently or continuously, at high speeds or low speeds? It also depends on how often you will use them. Many times it is mostly a matter of preference. Perhaps you would rather use less pressure and a carbide bur might be too powerful or aggressive for you. The carbides do tend to be more aggressive due to the larger teeth on most of them.
Here is a chart to help you decide which bur is best for various materials:
I hope this information gives you a better idea of which bur material will be best for the jobs you need to do. In part two, we’ll take a look at the various bur shapes and the tasks each is best suited to perform.
Psst—Did You Know?
No matter which of the metal types you choose for your burs, it is always smart (and profitable) to keep them sharp and corrosion-free by using a quality lubricant such as BurLife®. Not only does a lubricant help your burs last longer, it also reduces friction and chatter, contributing to a higher quality result every time you use the bur. Bur-Life comes in solid or liquid forms. Dipping in liquid works best for diamond burs, and the stick works great for all the rest. You can just touch the spinning bur to the stick and it’s good to go. For added convenience at the bench, check out the bench mount version.
Still have questions about burs and which ones to use? We’ll have Part Two in this series coming up. In the meantime, our Tech Team is happy to help you answer your questions, posted on this blog, as you search for the right bur for your jewelry making project!