Chop saw
In wood and metal processing, a chop saw is a machine for trimming (shortening) wood or metal in a vertical direction to the workpiece. If the saw is also moved in a horizontal direction, it is called a chopping saw .
The machines are as diverse as the wood dimensions, properties of the input material, the objective for the cut product and the degree of automation. In the simplest case, ordinary joinery circular saws or hand-held circular saws can be used for trimming .
Chop saw on the log yard
These are often designed as chain saws (sword saws ). The purpose is mostly to get two shorter pieces with less overall curvature from a long, crooked tree trunk (technically "block"). Sometimes it is better, in terms of yield, to get a larger and a smaller diameter as a raw part from strongly conical stems. Cutting out knots or other adhesions can also be useful.
Package chop saw
These are always designed as sword saws and are used exclusively to split whole packages of wood of great length into shorter lengths, or simply to calibrate the total length. The performance is very high due to the parcel-wise capping, but an individual cutting based on defects or wood quality is not possible. The cut quality is also usually rather poor.
Miter saw
These are often used as modified circular hand saws in the trade or in the DIY sector. A small miter saw is a (table) circular saw in which the angle of the cutting plane can be changed by tilting the saw blade. Picture frames are made in this way, for example .
The saw blade is tilted by tilting the entire saw head, which is attached via a joint. Miters can be made at any angle from about −45 ° to + 45 °. The exact cutting angle can be set using a scale.
The size of the saw blade of the miter saw determines the maximum cutting width and cutting depth. In the case of small models, only cuts (with a miter ) with about 25 mm in depth and 70 mm in length are possible, which greatly limits the scope of application. To increase the cutting width, many manufacturers also offer models with a pulling device. This makes it possible to pull the saw blade towards the operator via one or more rails. The large versions of a miter saw, on the other hand, offer almost the same cutting area that stationary circular saws have.
Miter circular saws are also available in industrial carpentry operations in very large and heavy designs with the highest degree of automation.
The accuracy of the angles often depends on the adjustability of the (90 °) guide rail. For the accuracy measurement of the advertised angle settings see circular saw # angle cuts and accuracy .
Chop, miter and table saw
In the mid-1990s, a number of manufacturers produced machine combinations of miter saws, and circular table saws. In cross-cut operation these do not differ from normal miter cross-cut saws. To achieve the functionality of a table saw, the saw blade could be locked in the lower position and the table could be tilted around the horizontal axis by 180 °. However, due to the often cumbersome assembly of the safety-relevant riving knife , which required a conversion every time the operating mode was changed, this was often left out. At the turn of the millennium, these types of machines almost completely disappeared from the market.
Radial arm circular saw
With this design (invented by Raymond E. DeWalt ) a cross-cut saw is usually guided along a cantilevered arm by means of rollers or roller bearings . The arm is swiveled out to produce miter cuts.
The saw can usually be rotated by 90 ° to enable longitudinal cuts for parallel trimming of wooden parts. As a result, however, the cutting table, which usually consists of a wooden board, is damaged and the cut-in stop bar interferes with the feed, since the riving knife pushes the workpiece away to the side for the cut.
The saw can also be swiveled for bevel cuts. The arm can be raised (similar to a bench drill ), and the saw, which is raised at the same time, enables grooves to be easily cut ( e.g. to produce a dovetail joint ). The Eumenia model from the former washing machine manufacturer Eudora , which is no longer in production , was a relatively inexpensive radial arm circular saw due to the lack of a lifting arm.
Undersink miter saw
These are classic industrial circular saws for trimming in sawmills, joiners' shops, carpentry shops or packaging departments of industrial companies. You have your own machine frame standing on the floor, from which the driven saw blade emerges after the workpiece is clamped by a protective and clamping device. Protective shields and two-handed operation are mandatory for accident prevention. Roller conveyors are installed in front of and behind the machine, usually with longitudinal stops on the exit side.
Cross-cut system
Cross-cut systems are high-performance machines that are usually equipped with cutting optimization. They always have an electronic length measurement and are controlled by a computer . Both the entry length before cutting is measured, as well as mostly the lengths of the flaws and the "good" distances between them. The desired finished lengths are stored in the computer as so-called parts lists. From the measured values and the parts lists, the computer calculates an optimal cross-cut pattern in terms of yield or value and controls the cross-cut machine automatically according to the optimization result. Sorting by length and / or quality is also computer-controlled.
Detection of imperfections
In the simpler (and still predominant) case, defects and qualities are recorded by a trained person marking the quality and defects using special chalk with bar codes. With the highest degree of automation, so-called Kapp scanners record the wooden surface of all four wooden sides in the longitudinal pass (up to 300 m / min) at least optically, sometimes also supplemented with X-rays . Using image processing methods, qualities and real flaws are then calculated according to many specifiable criteria, and an optimal cross-cut pattern is created from this.
commitment
Trimming systems are used in the large-scale industrial production of window scantlings, furniture friezes, glued wood panels, parquet, pallets, boxes, solid structural timber, glued laminated timber and the like. a.
High-performance cross-cut systems make more than 200 cross-cuts per minute. Often two or more lines also work in parallel.
See also
- Kappholz - wood scraps, sections