Marking out workpieces
What needs to be considered when scribing?
When scribing, contours, dimensions or drilling points are transferred to the surface of the workpiece to be machined. Various tools and aids are used for this. Accuracy is essential for a precise result, as errors during scribing affect the subsequent work steps.
Marking tool
The scriber is the best-known scribing tool, as it is used to transfer the scribe lines to the surface of the workpiece. Other scribing tools are
You can find out how to score with a scriber in our guide:
Marking process
Depending on the desired result, there are different methods for transferring the scribe lines to the workpiece:
- Marking parallel lines with a height marker
- Marking circular lines with a compass
- Determine circle centre with centring angle
3. procedure: Determine the centre of the circle
A centring angle consists of two legs that are arranged at right angles to each other and a ruler that bisects the angle.
A centring angle can be used to determine the centre of the axis or the centre point of cylindrical workpieces such as shafts.
Due to the structure of the centring angle, the ruler always runs through the centre of the workpiece - provided the angle is set correctly. At least two crack lines (at any angle to each other) are required to determine the centre point. This is because the intersection of the lines always runs through the centre of the circle of the workpiece.
Aids for scribing
To make fine crack lines on metal surfaces clearly visible, you can apply marking colour to the workpiece (Fig. 1). Marking paint is available both in the form of marking colour pens and as a liquid that can be applied with a brush. After scribing, the colour can be removed using solvent spray or orange oil cleaner, for example.
Marking on a marking plate ensures that the workpiece lies on a flat surface and therefore has a good hold.
Another aid is the clamping angle. This is used, among other things, to align a workpiece vertically to the machine table, but can also be used when scribing with the height scribe. The clamping angle aligns the workpiece to be processed perpendicular to the scribing plate and can therefore be scribed precisely (Fig. 2 and 3).
Correct scribing - tips & tricks
Note the following points when scribing:
- Draw the score line instead of "pushing" it.
- Stick to the scale specifications.
- Make sure that the surface for scribing is even and clean so that you can create even scribe lines.
- If possible, ensure that the workpiece surface is flat, as this leads to a better scribing result.
- When scribing, only apply enough force to create a light scribe line on the surface. Avoid scribe lines that are too deep.
Centre punching
Centre punching is the process of making small indentations on the surface of the workpiece using a centre punch and possibly a hammer. With automatic centre punches, a spring mechanism inside the tool triggers a self-impact effect when the punch is pressed down. With manual centre punches, the indentations are created on the material by lightly tapping the centre punch tool with a hammer. These indentations can be used, for example, to support a secure positioning of the drill bit on the surface. The centre punch can also be used to add contours and crack lines.
Hold the centre punch vertically and position it precisely to achieve optimum results.
Tip
Our scribing tools
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