Chisels for Wood Turning, How to choose?
The lathes used for the machining of parts are a powerful indispensable tool in the metal-mechanical industry. However, today's sophisticated lathes have their ancestors in ancient machines that appeared several centuries before the Christian era and that were destined to work the material available par excellence at that time: wood.
Woodturning is today a vast market that offers a variety of lathes used both in the wood industry and in carpentry, in the manufacture of furniture and wood crafts, and even in the home of a DIY enthusiast. It involves the use of hand tools that must be robust enough to withstand the vibrations produced during turning.
These tools resemble chisels and are therefore collectively referred to as turner chisels. Unlike traditional chisels, lathe tools are tempered and have different shapes, ergonomic wooden handles, and longer blades for better control and leverage.
Turner chisels consist of carbon steel, but this material tends to overheat during sharpening and continuous use.
High-speed steel chisels (HSS) retain their sharpness up to six times more than carbon steel, so the extra expense is worth the long run. Most industrial chisels are only available in high-speed steel.
Some manufacturers also market chisels in high-speed steel, a treatment that transforms austenite into martensite to produce steel with good wear-resistance properties and certain flexibility where the service life of the cutting edge is three times that of high-speed steel.
As a general rule, as long as you do not work with abrasive woods such as teak or elm, for example, carbon steel blades retain their sharpness for a long time.
On the other hand, when working with hardwoods or wet woods, high-speed steel tools are the option to follow. However, no matter what material they are made of, turning chisels must always be kept sharp - a blunt tool invites accidents - and there are numerous sharpening techniques for this purpose that needs consultation in due course.
Types of Chisels
We can point out that the tools or chisels for turning wood make up three large families:
Gouges: these are half-round steel plates. They have a curved cross-section and are sharpened only by the outer edge. They are generally long and require periodic sharpening which is why their length is decreasing. There are many different widths, each for a different function.
Bedan chisels: they are similar to gouges, but with a rectangular or square body and beveled finish which forms a sharp angle to attack the wood. They are used primarily to make deeper cuts in the wood. If they are handcrafted or for the home, they are usually from disused square files, but the trade has a great variety for a wide range of applications.
Chisels: chisels with more extensive (4 to 40 mm) and thinner (3 to 4 mm) blades that make shallower cuts that are for turning a smooth surface.
Classification of Chisels
Depending on their application, wood turning chisels have two primary groups, which can be combined to obtain the desired shape of the part:
Cutting chisels are most often used in profiling or thread turning or between points where the axis rotation of the lathe is parallel to the wood grain. Chisels and mowers or choppers which are the three most commonly used tools. They usually are sharpened to an edge similar to that of a razor blade when sharpened on both sides. Typically, stair rails, columns, and table or chair legs are profiled, among others.
Scraping chisels (usually called scrapers) are for turning to the disc or plate, where the axis of the rotation is perpendicular to the grain of the wood. They include universal gouges, chisels, and chisels with flat, round and oblique points.
These are not sharpened on flat sides, and the wire-like edges left after grinding are gone to aid in the scraping process. Examples of pieces turned to the plate are bowls, glasses, cups, or plates.
Moreover, there is a multitude of chisels for turning wood.
Roughing or half point gouges: These are always used for the first heavy work on the lathe, i.e., for converting parts with square or octagonal cross-section into cylinders. They are marketed in widths of 18, 25 and 32 mm, their shape is almost flat, and they allow to remove the full chips to obtain the first basic shape quickly. You can also use it for turning soft and semi-hard woods; the former is set to keep the tool at a very sharp angle, while the latter is attacked at an almost right angle. If you want to avoid clogging, the roughing gouges should not be inserted deeply into the wood.
Bowl or casting gouges: they are manufactured with central milling carried out on the round bar and are somewhat more closed in their curvature towards the interior (between 6 and 18 mm) to prevent getting caught from the initial casting of the bowl. The cutting bevel is elongated and has an angle of about 40º. These deep grooved gouges allow deep cuts when emptying. Extra-long 18mm gouges are also available for greater control when turning large diameter bowls.
Ring gouges are designed to prevent the corners of the gouges from sticking into the part. The circular or ring-shaped blade is an outer cutting blade with a diameter of 12 or 25 mm.
Mowers: basically, they are designed to cut the pieces and remove them from the lathe. Therefore, the blade, typically rectangular in section, although it may also be facetted or elliptical in part, has a grinding that produces an edge parallel to its narrow edges. The most common are:
Scraping tools (scrapers)
Profiling gouges: they have a round tip, a width of 6 to 25 mm and take the place of the roughing gouge in the turning to the plate. They are from a circle bar to which the central groove is milled, although there are also flatter profiled gouges that are manufactured as roughing gouges. The cutting bevel is more elongated and has an angle of 30-40º.
Straight cutting hatches and chisels: used for finishing parts in turning to the plate. The width of the blade ranges from 6 to 32 mm.
Oblique cut hatches: like straight cut hatches, you can use it for smoothing parts in turning to the chuck as well as for molding.
Round tip and convex tip chisels: used to work the inside of bowls and cups. The width of the blade can range from 12 to 25 mm.
Square tip shapes: these are used mainly on the outside of the bowls or the flat bottoms of turned boxes. They are produced in the same sizes as the round and convex varieties.
Side tip chisels: they are especially useful for working the inside of any emptied utensil. They have an 18 mm wide blade.
Diamond-tipped chisels: they generally have a sharp edge with a 90-degree angle. They are used to make "V" grooves in turned parts to the plate, as well as to clean corners at right angles. The width of the blade ranges from 6 to 32 mm.