2. Tools for Making Detachable Joints

Screwing is the most common type of joining mechanical or electromechanical components. For making or detaching such joints, screwdrivers and wrenches (spanners) of various types and sizes are used.

Srewdrivers

The types and sizes of screwdrivers required depend on the types of the screw.

Screwdrivers for slotted screws

Figure 1 - Screwdrivers 1 - 1 screwdriver with fixed blade, 2 spiral-ratched screwdriver

Figure 2 - Screwdrivers for recessed-head screws (Phillips screwdrivers)

When using screwdrivers, attention is to be paid to the following:

- The blades must perfectly fit into the slots of the screws.
- The clearance between the blade and slot must be very small.
- The width of the blade must be slightly smaller than the diameter of the screw head.

Figure 3 - Selection of a screwdriver - 1 screwdriver blade too small, 2 screwdriver blade too big, 3 correct screwdriver blade

What are the effects when using a screwdriver the blade of which is too small?

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Why must a screwdriver with defective handle not be used?
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Wrenches (spanners)

Wrenches differ with respect to their type and (width of) opening.

Figure 4 - Double head (open ended) wrenches

Figure 5 - Box wrenches (socket wrenches)

Figure 6 - Ring wrenches

When using wrenches, attention is to be paid to the following:

- Wrenches must suit the width across flats (wrench size) of the screw or nut.

Figure 7 - Wrench with nut - 1 wrench size

Why must the size of the screw/nut comply with the opening of the wrench?
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What tool can be used for slackening a nut if no suitable wrench is available?
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