Turning

from Wikipedia, the free encyclopedia

Turning is a machining production process for wood , more rarely also for horn , ivory , amber , alabaster , soapstone , serpentinite , acrylic glass ( Plexiglas ) and other plastics. The woodturner generally calls this process turning . Turning is done manually on a lathe or mechanically on an automatic lathe, with the workpiece in both cases rotating centrically around its axis in the horizontal plane and the tool moving along the contour to be generated.

The soapstone columns of the medieval temples of the late Chalukya - and in the Hoysala period ( India ) were also often turned.

history

The craftsmanship of woodturning was still unknown in the Neolithic Age , but goes back a long way to antiquity , with only smaller workpieces being processed at first. These were mostly clamped horizontally, turned with a fiddle bit and worked with a metal knife. Representations and reports have survived from Egypt and Roman times , but it is likely that this technique was also known early on in Mesopotamia , the Indus culture and China . In the course of time, the workpieces to be machined became larger and larger and reached their climax in the turned soapstone columns of the Chalukya and Hoysala times of medieval India .

Technology in the hand turning area

Long wood turning

Long wood turning

With this turning process, the workpiece is either clamped between the centers (driver on the headstock and center point on the tailstock) or attached to one side of the headstock. The workpiece rotates along the grain. The moving iron is placed on the palm rest and manually guided against the workpiece in such a way that a targeted cutting process occurs. This technique is used to make items such as:

  • Stair sticks
  • Stair posts
  • various pillars
  • Cans
  • Buttons
  • Writing implements
  • candle holder

This technique also includes hollow turning , turning overhead and thread cutting .

Wood turning

Wood turning

With this turning process, the workpiece is attached to one side of the headstock. The workpiece rotates across the grain. The moving iron is placed on the palm rest and manually guided against the workpiece in such a way that a targeted cutting process occurs. This technique is used to make items such as:

  • Bowls and plates
  • big rings
  • Handrail screws
  • Cans

Tire turning

With this turning process, the workpiece is attached to one side of the headstock. The workpiece rotates along the grain. The moving iron is placed on the palm rest and manually guided against the workpiece in such a way that a targeted cutting process occurs. The workpieces, mostly made of softwood, are completely soaked. Very finely contoured rings are turned using very long moving irons, which present their shape after being split - mostly animals or accessories for toys and figures.

winding column

Turning winding columns

Although this is primarily a combination of cutting, chiselling, rasping and grinding in addition to the actual turning work, the winding column is traditionally one of the turner's products. The basic shape is usually turned in long wood in preparation. The desired turns are recorded and cut to the intended depth using a hand saw. The rough shape is then chiselled with the chisel and finally brought to the desired shape and surface quality with various rasps and grinding materials. This technique is used to make articles like

  • Stair rungs
  • Chair and table legs
  • Bedpost

Oval turning

In this relatively rare turning process, the workpiece is attached to one side of the so-called oval mechanism or oval turning mechanism and this is attached to the headstock. The oval turning mechanism gives the mostly transverse wood workpiece a kind of transverse pendulum movement in one turn. The axis difference of the oval can be adjusted. In order to obtain an accurate oval, the tool must only cut exactly at a constant height to the axis of rotation during the turning process. This technique is used to make articles like

  • Bowls / plates
  • Cans
  • Picture Frame

Turn to fit

This is divided into longitudinal and transverse passig turning as well as mixed forms. In this extremely rare process, with longitudinal pass-through turning by means of a completely rebuilt lathe, the spindle is moved back and forth in the longitudinal direction by forced control, while the tool cuts or scrapes at a fixed point. When turning crosswise, the spindle or the entire headstock is set in an inevitable cross pendulum motion. Both methods use templates and cams to determine the amount of deflection. The workpieces should be made of solid, homogeneous material. Since the workpiece is mostly guided in the support, one can hardly speak of turning it by hand. The tool can only be guided freely with simple straight turning work. This technique is used to make articles like

  • Stair rungs
  • Table legs
  • Cans

Thread cutting tools (also thread cutting tools)

This method is rarely used in the professional field, but is sometimes taught in specialist classes. Internal and external threads can be produced on workpieces with internal and external streamers (screw tools). The slower the lathe runs, the easier it is to cut a thread. With the workpiece rotating, the tool is placed at the base of the desired thread and moved forward with little pressure. The aim is to cut one thread turn per revolution. If the feed rate fits, the movement is repeated until the desired depth of the thread is reached. This procedure requires a great deal of practice and skill. Evenly grown woods with a high density are used (pear tree, apple tree, plum tree, boxwood, hornbeam, etc.). Horn and bone (bones) are also suitable. The alternative to thread steels in wood are cutting tools similar to those used in metalworking.

This technique is used to perfect articles such as B.

  • Lathe chuck
  • Tube screw connections
  • Pipes

Tools

The essential tools of the turner are:

  • Tubes = semicircular tools with flat external grinding
  • Flat chisels and parting tools = with flat, sometimes double-sided grinding for cutting the workpiece to length.
  • Finishing and boring steels = with a very steep cut

As a measuring instrument, the stylus has now been replaced by a caliper. Other measuring and auxiliary instruments of the spring inside caliper and the dividers . These can be found, together with the external spring button and the perfect basic shape - the ball - in the turner's guild symbol .

Even if the tools are similar to carpenter's tools, they are fundamentally different due to their characteristics and properties. In particular, the length of approx. 40–50 cm and the greater strength are of considerable importance for reliable turning.

literature

Web links

Commons : Woodturning  - collection of images, videos and audio files

Individual evidence

  1. ↑ Bernhard Nepelius: The history of wood turning