(or, Learn from my mistakes) Thanks to Lumberjocks
So you bought a new rotary carving tool and need to buy some carving burrs, eh? Confused? I bet you are. The new power carver can easily become befuddled with the bewildering array of burr choices on the market. Hopefully this article will help you avoid buying the wrong burrs for what you need to do.
Burrs come in plenty of different shapes, types, sizes, and materials. You can find them with diamonds, rubies, ceramics, and various oxides of all sorts. Then there are HSS, carbide, carbon steel, etc.. Add fluted, structured carbide, and a few other types and you’re soon as confused as can be. I’m still not sure I have it all down, but I’ve certainly spent too much money, and have drawers full of burrs I should not have purchased.
One of the considerations when buying burrs is to examine what type of carving you will be doing. Will you be carving lifelike birds, or other animals, or will you be making other types of objects, like spoons for example? Maybe you’re carving Santa figures, or whimsical sailors or something. The types of burrs you’ll need differ based on type of carving. We will be discussing carving burrs in order from least detailed carving to most detailed, and then get into a discussion of burr shapes/profiles. Mostly though this article will deal with burr type as opposed to burr shape.
Carving is a reduction activity – that is we are removing material from our product rather than adding it as in clay making, for example. There are therefore times when you will want to remove large amounts of wood in a hurry, while composing or following a prescribed shape. Burrs suited to this purpose leave very rough surfaces, cut very aggressively, but can be very sensitive to grain direction, too. Some burrs are more sensitive than others. I have found carbide based burrs to perform better than HSS or carbon steel tools, as well as never needing to be sharpened. There are both fluted (edged) and abrasive carbide burrs. The abrasive burrs come in several flavors as well. These are the safest choice for beginners as they are generally indifferent towards grain direction.
Abrasive burrs come in structured and unstructured formats. The two types I prefer best are sold under the Typhoon, Saburr, and Kutzall brands. Typhoon/Saburr burrs have cutters that are aligned with each other in rows whereas Kutzall burrs are mostly randomly arranged on the burr head. The cutting action is similar but the Typhoon burrs will remove wood more quickly and do not seem as prone to burning the surfaces of some woods, and they work better in burls that have swirling grain directions. Another advantage is that they clog far less.
Here you can see the difference between a Typhoon and a Kutzall. The Typhoon is on the left. Saburr in the middle and Kutzalls on the right. Several carving supply sites have recently dropped the Kutzalls in favor of the Typhoon/Saburr type burr.
Another type of roughing burr is the “stump cutter”. I don’t like them, but they must be very popular as they’re in about every catalog. I find them inadequate compared to the other types of roughing burrs.
One of my favorite cutters is the fluted or ‘edged” carbide burr. They cut quickly and leave a remarkably polished, clean surface, often devoid of any defects. Another advantage of them is that they produce larger chips that fall to the ground rather than dust which might remain suspended in the air. The main downside of these burrs is that they can be very sensitive to grain direction and rotational speed. Cutting “uphill” is not productive and can result in digs, nicks, and kickbacks. A slow bit speed will also detract from this burr’s usefulness.
These fluted bits can also be found in a “doublecut” arrangement. The doublecut is meant for working in metal but I find these very good for woodworking, less sensitive to grain orientation, and produce a very nice finish. Here is a standard cut burr..
The “Monster” carbide burrs are VERY good tools. I would not recommend buying steel carving bits, not only do they not perform well, they don’t last and it is a waste of time to try and sharpen them. HSS or high speed steel tools are an acceptable compromise, but carbide cuts and lasts best.
For roughing work, the types mentioned above are my favorites and seem to work the best. You can find roughing bits in 1/4”, 3/32” and 1/8” shanks, but they really shine in a powerful tool with a 1/4” shank.
Unstructured and structured carbide bits are also available in different grits. Use them in the same order you would sandpaper, and don’t hesitate to buy fine grit carbide burrs. They will save you LOTS of sanding time.
Detail work is generally the work of smaller tools, with detail bits and burrs typically found mounted on 1/8” or 3/32” shanks. Burrs are available in several different media and a befuddling array of shapes/profiles in this category.
Ceramic, or “ceramcut” stones are available in several grits, generally blue being the roughest. The blue ceramcut stone is great for texturing and detailing and is available in all sorts of profiles. Try a couple or buy a small set. Red ceramic stones are next up in the grit rating (smoother), and white stones are for polishing. White stones can be great for adding detail lines, veins, feathers, etc.. Most all of the ceramic stones can be reprofiled to your liking by holding them up to a diamond stone or file as they rotate.
Diamond and ruby and sapphire stones are an alternative to ceramic stones. Ruby stones cut more coarsely than diamond. Ruby stones are susceptible to damage from heat and pressure, so care should be taken when using them. I prefer the ruby stones to diamond stones in almost every case. They are great for gentle shaping and adding details. Both diamond and ruby burrs wear more quickly than ceramic, and not all diamond burrs are created equal. The cheap ones are – cheap and you will find that the diamond pieces are irregularly sized, leaving a badly finished surface. The better diamond stones are great. The advantage of the sapphire burr is they last longer than the ruby.
In my opinion, these things are incorrectly named, and it causes confusion. “Sanding sleeves”, such as those offered by Typhoon, can be aggressive carving tools. They are inserted over a rubber drum on a ¼” mandrell and come in different grits. These are fantastic tools and though straight profiled, excel at creating convex surfaces such as spoon bottoms and handles. They do not produce what you would consider a sanded surface at anything other than a rough grit.
Lastly, there are bits that don’t fit into any real category described above. They have unique uses.
“Dura Grit” abrasive cutters are tough, tungsten carbide cutters. They are not as aggressive as a typhoon but much more so than a ruby. They come in 1/8” shanks. Get them at LeeValley.
Vanadium steel burs
I think these things are junk. With the easy availability of carbide and HSS burs, I just don’t understand why anyone would want to bother with these vanadium burrs. I notice that Lee Valley has discontinued them.
My carvings generally use 3 basic shapes of burr – straight, round, and flame.
The straight shape is used for creating curved surfaces on exteriors. It sounds counterintuitive but it works better than using a round or a flame shape. Trust me on this. I use flame and round, generally spheres as opposed to ovals, to produce concave interior surfaces like those of a spoon or bowl shape. As most of my work these days is not detail oriented I don’t typically need any of the pointy shapes you see in the picture above, but they have their place. You will have to experiment to find the shapes that work for you, or consult a woodcarving website that has a bunch of detail carvers.