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During sawing particles are removed by the sawing teeth in a saw kerf.
Figure 1 Cutting by saw teeth
Many triangular sawing teeth placed one after the other cut the wooden material.
Which parts does the sawing blade consist of?
1. ________________________
2. ________________________
3. ________________________
4. ________________________
5. ________________________
6. ________________________
Figure 2 Parts of the saw blade
1 saw blade, 2 saw tooth, 3 tooth space, 4 tooth point, 5 tooth gullet, 6 tooth face
The angle between
- the tooth face and- the top line of teeth (breast) is responsible for the cutting efficiency of the different types of saws. This angle is called
- cutting angle.
Figure 3 Cutting angle
1 tooth face, 2 tooth top line, 3 cutting angle
For manual sawing the following types of teeth are used:
- The teeth are arranged for push-type cutting
· the cutting angle is 90°
· cutting is effected in pushing direction only
· high effort is necessary
· well suitable for sawing of wood with the grain
· not suitable for sawing of wood across the grain and of chipboards.
Figure 4 Push-type cutting teeth
1 cutting angle at 90°, 2 cutting is effected in pushing direction
- The teeth are arranged for push-and-pull type cutting
· the cutting angle is larger than 90°
· cutting is effected in pushing direction and scraping in the opposite direction
· low effort is necessary
· well suitable for sawing of wood across the grain
· when sawing wood with the grain there is a low cutting efficiency
Figure 5 Push-and-pull type cutting
teeth
1 cutting angle larger than 90°, 2 cutting is effected in pushing direction
How do hand saws
work?
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The teeth of the saw blade are bent alternately to the left and to the right of the saw teeth top line to avoid jamming of the saw in the wood during sawing.
- This bending of the teeth is called setting.
- Set saws make it possible for the saw blade to move freely in the kerf.
Figure 6 Set teeth
- The kerf is wider than the saw blade’s thickness.
Figure 7 Saw blade with kerf
What are the reasons for jamming of saws in the
wood?
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