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Cross-Cutting[edit | edit source]

GENERAL RULES FOR CROSS-CUTTING[edit | edit source]

If the tree is not skidded to a landing for cross-cutting, this operation should be done in the forest by the same team which does the felling and debranching to avoid delays and additional time spent on getting to the tree. However, this process requires the presence of qualified supervisors or availability of workers having basic knowledge in timber grading unless only fuelwood is to be produced.

The greatest care is required to avoid losses in cross-cutting valuable trees. They should be thoroughly inspected for proper grading before cross-cutting begins. Clear instructions should be given for the grading of different logs. Simply cutting trees from the bottom into uniform log lengths may result in much wastage during utilisation.

A single tree may be cut into different assortments: for instance, higher-quality logs for the sawmill (1a), lower-quality logs for a chipboard plant (1b), and fuelwood (1c). Skilled grading can considerably increase the economic returns of the operation.

In many sawmills, it is common for saw logs to go straight from the forest without further cross-cutting into conversion. In such cases, tree shape and quality must be carefully assessed to allow a reasonable degree of recovery in the mill. Heavily tapering trees should therefore be cut into shorter lengths than straight trees with little taper (2). Minimum and maximum log length and size, however, will depend on transport facilities.

Crooked logs should normally be cross-cut in the bend and not between the bends (3).

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TOOLS FOR CROSS-CUTTING[edit | edit source]

For cross-cutting small-sized trees, e.g. for fuelwood, a portable support should be used (1). This facilitates the job and avoids contact of the sharp cutting tool with the ground. This type of support can easily be made on the spot and transported within the forest (see page 92).

Bow saws are handy for cross-cutting up to a diameter of 20 cm (2).

Above diameters of 20 cm, the bow saw should be replaced by the cross-cut saw (3).

To avoid pinching of the saw, wedging is required (4).

Furthermore, tools for correct measuring are needed, such as measuring sticks, tapes or calipers.

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SUPPORTS AND TRESTLES[edit | edit source]

These are made locally and used as an aid for work such as debarking and cross-cutting in the stand, at the roadside, landing or timber yard. In many cases, work is done more easily and quickly when using supports and trestles. Moreover, tool edges remain sharp for a longer time if work is not done close to the ground.

A forked branch is the easiest means of supporting a pole if rested against a standing tree in the forest (1).

Dovetail trestles consist of a wooden post and two legs. They can easily be made in the forest with no other tools than an axe and a bow saw. Dry and light wood is used. Two dovetail cuts are made on one end of the post (2). The top ends of the legs are square on three sides (3) and fitted into the dovetail cuts.

The low dovetail trestle (4) consists of a post 200 cm long and 12 cm thick (4a). The dovetail cuts 25 mm deep are made about 20 cm and 40 cm from the end. The legs are 70 cm and 80 cm long and about 7.5 cm thick. They are inserted into the dovetail cuts from below. Their feet should be about 65 cm apart. The top of the longer leg must be so fitted into the dovetail that it is 10 cm higher than the post. This extended leg and two notches made in the lower end of the post provide three resting positions for poles which can be put on to the trestle by tools such as a log turner or a sappie.

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CROSS-CUTTING OF TREES UNDER TENSION[edit | edit source]

Cross-cutting of trees under tension may cause loss of wood and may also pinch the saw. This should be avoided as much as possible through special techniques.

Tension can often be reduced by putting supports under the tree (1a). If this is not possible, e.g. in a tree where the upper side is under tension and the lower side is accessible, then cross-cutting should be done from below (1b) until the saw starts jamming and then continued from above (1c).

If the lower side of the tree is under tension, an effort should be made to place a support under the tree (2a). In this case, sawing should start from above until the saw starts jamming (2b) and be continued from below (2c) unless wedging is feasible and sufficient.

In windfalls, cross-cutting under tension is very common. As shown on pages 98 and 99, a pressure rope or cable can be used in such cases to avoid cracking. Such equipment may in special cases also be useful in other harvesting operations.

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WOOD WASTAGE IN CROSS-CUTTING[edit | edit source]

Cross-cutting with axes should be avoided (1a). In large-sized wood, losses of 30 per cent of the total volume may occur if wood is cut into lengths of 1 m or less. The saw cut wastes only a minimal amount of wood and requires less effort than axe work (1b). Furthermore, a clean saw cut allows more precise measurement and stacking as well as denser loading in transport.

If cross-cuts on logs are not made at an angle of 90 (2a), wood is usually lost during utilisation since logs may require corrective cross-cutting.

Cutting from the side which is under tension causes the log to crack. This may be an advantage in special circumstances when the log would have to be split anyway into fuelwood or pulpwood. However, valuable logs should never be reduced by careless cutting to fuelwood quality (3a, 3b).

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Authors Eric Blazek
License CC-BY-SA-3.0
Language English (en)
Related 0 subpages, 0 pages link here
Aliases Wood Harvesting with Hand Tools 11, Original:Wood Harvesting with Hand Tools 11
Impact 433 page views
Created April 4, 2006 by Eric Blazek
Modified December 9, 2023 by Felipe Schenone
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