Segmented turning
Encyclopedia
Segmented turning is turning on a lathe
where the initial workpiece is composed of multiple glued-together parts. The process involves gluing up several pieces of wood to create patterns and visual effects in turned projects.
Segmented turning is also known as polychromatic turning.
In traditional wood turning, the template is a single piece of wood. The size, grain orientation and colors of the wood, will frame how it can be turned into an object like a bowl, platter, or vase. With segmented turning, the size and patterns are limited only by imagination, skill and patience.
While the vast majority of segmented turnings are vessels of one sort or another, strictly speaking, any turned object comprising multiple pieces of glued wood could be classified as a segmented turning. Examples include pens, salt and pepper mills, and rolling pins. By cutting and re-assembling pieces after they are turned, unique forms can be created, crossing over to pure art. See for example the work of Malcolm Tibbetts.
In addition to design skills, segmented turning demands precision woodworking skills as well as turning skills. Design and construction of a bowl blank—the wood piece mounted on the lathe for turning a vessel—requires angled miter joints cut to tolerances of as little as a tenth of one degree or better.
There are essentially two different techniques for constructing a bowl blank, ring construction and stave construction.
Ring construction is the most common. A ring-constructed blank comprises rings glued in a cylindrical stack. Though a platter or shallow bowl could be made from a single ring, stacking many rings is more typical. Apart from a lid or a base made and added after the fact, the height of the finished piece is a function of number of rings, and the height of each ring, which of course can vary for effect. Each ring comprises three or more pieces cut and glued to form a triangle, square, pentagon, hexagon, etc. The more pieces in a ring, the more challenging for the turner, because there are more opportunities for precision errors—gaps and misalignments in the joints between pieces. The individual pieces making up a ring themselves are often assembled from smaller pieces of contrasting or complementary colors to achieve striking patterns in the finished piece. This too adds to the complexity and challenge for the turner.
Native American pottery, basket, and textile designs, particularly from the southwest U.S., frequently inspire form and design features. These patterns are often geometric in design and thus are easier to recreate than more fluid forms found in nature.
Stave constructions are assembled like barrels—cylinders constructed from multiple long, vertically-oriented pieces. As a rule, the grain in a ring-constructed turning runs horizontally in the finished piece, while the grain in a stave-constructed turning runs vertically, from top to bottom.
Another category of segmented turning called Open Segmented Turning is similar to ring construction but small gaps are left between the segments. Successive rings are offset so the segments interlock with the ring above and below. This type of segmentation seems very delicate and is somewhat transparent but it is generally quite strong. This concept was introduced by Yosh Sugiyama in the early 1980s. For example see the work of William Smith.
A segmented turning can combine ring construction, stave construction, and solid, non-segmented wood as well in a single piece. However, wood expands and contracts in the direction perpendicular to its grain as a function of its moisture content, itself a function of ambient humidity. In this case, during design and assembly, the turner has to be mindful of the impact on long term structural integrity of assembling the constituent pieces into incompatible, non-parallel grain directions.
An important variation of the ring construction technique is known as "bowl from a board." Imagine a flat, square board bisected to create two identical rectangles, like two twin beds placed side-by-side to form a king-sized, square bed. Rings are created by cutting concentric semicircles from each of the two boards, one concentric half-ring a mirrored-shape of a half-ring from the other. The semicircles are typically cut with a bandsaw, but a scrollsaw, jigsaw, or coping saw would work. The blade of the saw used to cut the semicircles is set at an angle from the vertical, typically 45-60 degrees, such that when each mirrored pair is glued together to form a complete ring, the rings are shaped like cross sections of a cone. The rings are then stacked to create a cone-shaped blank. An incredible variety of visual effects can be achieved as a function of how the boards are constructed before the concentric rings are cut.
There are ongoing discussions as to whether turning is a trade, craft, or an art form. Turning in its original form was certainly utilitarian. If your last name is "Turner" chances are there was a production wood turner some generations ago in your family tree. Many turners produce spindle work for furniture, architectural work, toys, and of course, bowls. But in recent years, many artists use turned pieces as a canvas for carving
, pyrography
, gold leaf
work, inlay
, stain
and painting
.
Lathe
A lathe is a machine tool which rotates the workpiece on its axis to perform various operations such as cutting, sanding, knurling, drilling, or deformation with tools that are applied to the workpiece to create an object which has symmetry about an axis of rotation.Lathes are used in woodturning,...
where the initial workpiece is composed of multiple glued-together parts. The process involves gluing up several pieces of wood to create patterns and visual effects in turned projects.
Segmented turning is also known as polychromatic turning.
In traditional wood turning, the template is a single piece of wood. The size, grain orientation and colors of the wood, will frame how it can be turned into an object like a bowl, platter, or vase. With segmented turning, the size and patterns are limited only by imagination, skill and patience.
While the vast majority of segmented turnings are vessels of one sort or another, strictly speaking, any turned object comprising multiple pieces of glued wood could be classified as a segmented turning. Examples include pens, salt and pepper mills, and rolling pins. By cutting and re-assembling pieces after they are turned, unique forms can be created, crossing over to pure art. See for example the work of Malcolm Tibbetts.
In addition to design skills, segmented turning demands precision woodworking skills as well as turning skills. Design and construction of a bowl blank—the wood piece mounted on the lathe for turning a vessel—requires angled miter joints cut to tolerances of as little as a tenth of one degree or better.
There are essentially two different techniques for constructing a bowl blank, ring construction and stave construction.
Ring construction is the most common. A ring-constructed blank comprises rings glued in a cylindrical stack. Though a platter or shallow bowl could be made from a single ring, stacking many rings is more typical. Apart from a lid or a base made and added after the fact, the height of the finished piece is a function of number of rings, and the height of each ring, which of course can vary for effect. Each ring comprises three or more pieces cut and glued to form a triangle, square, pentagon, hexagon, etc. The more pieces in a ring, the more challenging for the turner, because there are more opportunities for precision errors—gaps and misalignments in the joints between pieces. The individual pieces making up a ring themselves are often assembled from smaller pieces of contrasting or complementary colors to achieve striking patterns in the finished piece. This too adds to the complexity and challenge for the turner.
Native American pottery, basket, and textile designs, particularly from the southwest U.S., frequently inspire form and design features. These patterns are often geometric in design and thus are easier to recreate than more fluid forms found in nature.
Stave constructions are assembled like barrels—cylinders constructed from multiple long, vertically-oriented pieces. As a rule, the grain in a ring-constructed turning runs horizontally in the finished piece, while the grain in a stave-constructed turning runs vertically, from top to bottom.
Another category of segmented turning called Open Segmented Turning is similar to ring construction but small gaps are left between the segments. Successive rings are offset so the segments interlock with the ring above and below. This type of segmentation seems very delicate and is somewhat transparent but it is generally quite strong. This concept was introduced by Yosh Sugiyama in the early 1980s. For example see the work of William Smith.
A segmented turning can combine ring construction, stave construction, and solid, non-segmented wood as well in a single piece. However, wood expands and contracts in the direction perpendicular to its grain as a function of its moisture content, itself a function of ambient humidity. In this case, during design and assembly, the turner has to be mindful of the impact on long term structural integrity of assembling the constituent pieces into incompatible, non-parallel grain directions.
There are ongoing discussions as to whether turning is a trade, craft, or an art form. Turning in its original form was certainly utilitarian. If your last name is "Turner" chances are there was a production wood turner some generations ago in your family tree. Many turners produce spindle work for furniture, architectural work, toys, and of course, bowls. But in recent years, many artists use turned pieces as a canvas for carving
Wood carving
Wood carving is a form of working wood by means of a cutting tool in one hand or a chisel by two hands or with one hand on a chisel and one hand on a mallet, resulting in a wooden figure or figurine, or in the sculptural ornamentation of a wooden object...
, pyrography
Pyrography
Pyrography is the art of decorating wood or other materials with burn marks resulting from the controlled application of a heated object such as a poker. It is also known as pokerwork or wood burning....
, gold leaf
Gold leaf
right|thumb|250px|[[Burnishing]] gold leaf with an [[agate]] stone tool, during the water gilding processGold leaf is gold that has been hammered into extremely thin sheets and is often used for gilding. Gold leaf is available in a wide variety of karats and shades...
work, inlay
Inlay
Inlay is a decorative technique of inserting pieces of contrasting, often coloured materials into depressions in a base object to form patterns or pictures that normally are flush with the matrix. In a wood matrix, inlays commonly use wood veneers, but other materials like shells, mother-of-pearl,...
, stain
Wood stain
A wood stain consists of a colorant suspended or dissolved in a 'vehicle' or solvent. The suspension agent can be water, alcohol, petroleum distillate, or the actual finishing agent...
and painting
Painting
Painting is the practice of applying paint, pigment, color or other medium to a surface . The application of the medium is commonly applied to the base with a brush but other objects can be used. In art, the term painting describes both the act and the result of the action. However, painting is...
.
Artists
- Malcolm Tibbetts's Website
- Steve Bernstein's Website
- Traditional Woodturning from Sherwood Forest
- MarleyTurned Website
- Greg Sayers Website
- Bob Pritchard's Website
Software and Instruction
- Segmented Turning web site for segmented software.
- Woodturner PRO web site for segmented software.
- Segmented Turning Videos: Calculations, Cutting Tips, Glue-Up Procedures Clamping Alternative - from woodtreks.com
- The Segmented Turner How-To's, Tips, Videos and more.
- Segmented woodturning projects Segmented woodturning instructions.