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Exact knowledge of the working techniques “Measuring and Scribing” is essential for good working results. Therefore they haw to be carried out carefully and to be checked conscientiously. The following activities are distinguished with regard to the techniques:
- drawing of parts belonging together
- measuring and scribing on one plane (mainly on wide faces)
- measuring and scribing on two planes (wide and narrow faces)
For making wide face joints the piece parts are marked with a triangle. Thus mixing up or incorrect joining is avoided.
Figure 3 Drawing of piece parts of a
wide face joint
The drawing of frame joints and face comer joints is done in two stages:
- marking the reference edge (bevelled edge) with an angle sign
- after selecting and placing together the parts, the parallel parts are marked with a triangle.
Figure 4 Marking of an angle
reference edge
1 angle reference edge with angle sign
Figure 5 Marking of frame parts
belonging
together
When measuring sawn timber panels, pay attention to small losses with regard to the use of these materials. The sequence of operations includes the following activities:
- Prepare the necessary tools and materials (e.g. drawings).- Put the board on the work bench (best side to the top).
- Mark the length reference edge with a pencil and a straightedge.
- Measure the width of the workpiece (pay regard to the working allowance and the cut) on three places and scribe with the straightedge and the pencil.
- Measure the workpiece length at the length reference edge (pay regard to the working allowance) and scribe with the working square and the pencil.
- When drawing the pencil line, pay attention to the exact leading of the pencil.
- Check the measurings.
Figure 6 Scribing of a length
reference edge
Figure 7 False and right leading of
the pencil
(1) right, (2) false
Why must the workpieces be scribed before being
processed?
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When can wanes (or parts of them) remain in the
workpiece?
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When sawing to final size and scribing wood joints, it is necessary to mark two or more faces (wide and narrow faces) with scribed lines and dots.
According to the required accuracy the measuring can be carried out with a folding rule, a measuring tape or a steel rule. For scribing are used: a scriber, a marking gauge and in case of faces which are visible after being worked a sharp pencil. The wood to be scribed is smoothened, planed to width and thickness, marked with angle signs and drawn together.
The sequence of operations includes the following activities:
- Prepare the necessary tools and materials (drawings or front view).- Clamp together parallel running woods with a screw clamp (angle signs to the top).
- Measure the finished size length and scribe with the scriber and the working square.
- Measure the finished dimensions and scribe them with the scriber and the working square.
- Unclamp the woods.
- Transfer the necessary markings angularly.
- Set the marking gauge to the required sizes.
- Put the marking gauge against the angle face of the work-piece and scribe as many faces as necessary.
- Compare the sizes of workpiece and drawing.
Figure 8 Scribing the finished
dimensions
1 inside length, 2 width of the cross frame woods
Figure 9 Transferring the markings
angularly
Figure 10 Scribing of the parallel
markings with a marking gauge
Why are the visible faces scribed only with a
pencil?
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When manufacturing workpieces with rounded edges (rounded comers and surface roundings), in case of single-part production the form can be constructed and scribed directly on the face of the parts. If several forms of the same kind are required, scribing should be carried out with templates. Before preparing the templates it is to be decided whether they should get a working allowance or not. When preparing the templates you should work carefully because possible inaccuracies recur on all parts being scribed afterwards.
Scribing with a template is relatively simple and includes the following activities:
- Prepare the necessary tools and templates.- Put the workpieces on the work bench.
- Place the templates so that the flow of the wood fibres guarantees greatest consistency and that possible wood defects can be cut off.
- Scribe the form of the template with a pencil.
- Check the scribed lines.
Figure 11 Scribing with a template
1 flow of the wood fibres, 2 wood defects
Which advantages has the application of templates for making
equally curved
parts?
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