Hand Tools: Screwdrivers
Here you will find detailed information about different types of Hand Tools, in this item the Screwdrivers group is discussed!
What does a screwdriver consist of
A screwdriver consists of a handle, a shaft, the blade and sometimes a cam for a spanner.
Handle (Heft or Hecht)
Turning in a screw is a rotating movement. This rotating movement is created in the handle. The purpose of the handle is therefore to transfer the force of the hand via the handle to the blade. Many suppliers are constantly experimenting to design the ideal handle so that their product has the best power transmission.
There are often slots in the handle in the longitudinal direction. In these grooves, the skin fold of the hand can get stuck at the moment that force really has to be applied. This creates a great unity between hand and handle and more force can be applied. Without these slots, significantly more force must be applied to tighten the screw. In addition, extra force is required to prevent the screwdriver from slipping in the hand. With screwdrivers without slots, an attempt is made to prevent slipping by applying anti-slip surfaces to the handle. A second disadvantage of a handle without slots is that the skin folds of the hand can become double. As a result, there is a risk of blisters.
What is a handle made of
The handles of screwdrivers are made of plastic or beech wood. It should be noted that the handle made of beech wood is increasingly disappearing from store shelves. With plastic handles, the handle is pressed into the handle, or the handle is molded around the blade. The screwdriver with which the handle is pressed into the handle is more robust than the handle which is cast around the handle. With molded handles, a small amount of shrinkage of the plastic occurs during the cooling down of the production process, resulting in play.
Most of the producers use the plastic cellulose acetate in the preparation of their handles. Three exceptions to this are.
Paul Baumann (PB)
The plastic cellulose acetobutyrate is used in the production of handles. This plastic is insensitive to voltage differences, is cadmium-free, has a high impact resistance, has a pleasant feel (raw material is natural fiber for cotton), is resistant to petrol and mineral oils, is poorly combustible and insensitive to weather influences.
The plastic Weralit II is used in the production of handles, which according to its own words is cadmium-free, oil and acid resistant and has a high impact resistance.
Recently, the plastic polypropylene in combination with the soft thermoplastic Elastomer has been used in the production of handles.
Because both PB and Wera produce a handle that is cadmium-free, they do not have to change their handle to the state of the latest environmental requirements. Many manufacturers did use cadmium and are therefore busy removing this substance from their production process. A number of manufacturers give their handle a color to indicate a distinction between the different production lines.
For example, the screwdrivers of the Gedore brand have as color classification:
- Blue, intended for industrial use.
- Black, intended for medium use.
- Yellow intended for the hobby application.
Impact resistant or not impact resistant
If an object, such as a hammer, is hit on the back of the handle, the handle should of course not split. If the handle does not split it is called an impact resistant handle. If the handle is split, the handle is clearly not impact resistant. Splitting a handle is often due to an incomplete production process. During the production process, uneven hardening occurs during the hardening process. We see this phenomenon especially where cheap plastics are used.
There are two cams on the stem. The purpose of these cams is to transfer the force from the handle to the stem. There can also be a hexagon on the handle, which may fit a socket wrench, with which an extra force can be applied. In addition, the stem can be insulated or blank.
The steel used in the screwdrivers of the PB brand is special PB spring steel. PB spring steel is a special steel alloy developed by PB itself. This steel has unparalleled hardness and toughness. For example, the hardness is 58 – 60 rockwell, with normal tool steel the hardness is 55 – 57 rockwell. With a PB screwdriver, this extra hardness is the same over the entire blade, not just at the point. A drawback of a handle with too great a hardness is that the screwdriver can break under a great load. That is why PB has added extreme toughness to its tool steel in addition to great hardness.
The blade of a screwdriver is actually the most important part. The shape and size of the blade determine which type can be screwed tight or loosened. To determine which screwdriver is needed, it is necessary to consider which screw head is on the screw. The screw heads can be divided into screw heads with:
Slotted cut – Pozidrive cross head – Phillips cross head – Torx
A slotted screw head is the most common. The blade for this type of screw head is examined in more detail. The blade for a slotted screw head can have a conical or parallel forged fold. The screwdrivers of the brand PB have a parallel fold. This fold, also called the parallel or the Swiss fold, has the advantages over a conical fold that:
A conical fold does not fill the groove as well as a parallel fold. A screwdriver with a conical fold must always be pressed straight into the saw groove. If the user does not do this, the correct torque will not be achieved. With a conical fold, a force is quickly created that pushes the blade out of the saw slot. With a parallel fold a torque can be achieved which is 50% greater than with a conical fold.
With most screwdrivers the tips of the blade protrude, with the blade of PB these tips are ground. This makes it possible to tighten a screw that is recessed in the workpiece. The blade thus fills the entire cutting slot. The best power transmission is obtained by taking a blade which completely fills the saw slot. To solve this problem, other manufacturers are making the tray size smaller. These producers then give a blade with a thickness of a number 4, but with the width of a number 3. This of course fits well, but it cannot be used to exert that much force. The screwdrivers with a different thickness compared to the width are of course very strong. This is because the thickness is not entirely correct in relation to the width. A disadvantage of this deviation is that there is a greater chance that burrs will be turned on the screw.
A PB brand screwdriver with a number 4 is intended for an M4 screw. A screwdriver number 5 for an M5 etc. With other brands we find for example 1.0 * 6.5 as designation. With this last indication it is considerably less clear to deduce which screwdriver the user should have.
Impact wrenches are used with screws that are very tight or must be very tight. Think of tightening and loosening screws in a car door, these screws often cannot be loosened normally.
With an impact screwdriver, the screwdriver bit is in a 5/16 connection. Because strong forces are suddenly on the bit, a normal screwdriver bit should not fit in this connection because it would be destroyed quite quickly. On the back, the impact screwdriver is located a flattened piece. This is struck with a hammer when used.
The downward movement resulting from this is converted into a very strong lateral force in the impact screwdriver. The screw is moved with this force. The screw scares loose, as it were. Instead of a screwdriver bit, a socket wrench can also be placed on the impact screwdriver. Most impact screwdrivers are adjustable either left or right hand rotation.
Well-known within this group are the watchmaker screwdrivers. These screwdrivers vary from blade size 0.6 to size 3.8 mm. On the back of these screwdrivers is a ring, which is loose. A finger rests on it during use. Use the other fingers to turn the screwdriver. In addition to screwdrivers, the precision tools also include crosshead, open-end wrenches, hexagon socket and socket wrenches.
Voltage finders and voltage testers
A voltage detector is a handy little screwdriver that is used to check whether voltage is present on an installation. A tension detector is often provided with a clip to carry the tension detector in a jacket pocket or overalls. During use, the stem of the voltage tester must be held against the object, eg in a socket, by putting a finger against the back of the screwdriver we create a closed circuit. When the neon light comes on, power is supplied to the installation. A voltage tester tests from 90 to 500 volts. In addition to the version already described, there is also a version with a cable with a crocodile clip on the back. This can also be used to create a closed circuit.
Part of the voltage detectors are the low-voltage testers. These testers are often used in the automotive industry. These testers have versions that are equipped with a thin needle that can be inserted through the cable, so that it can be tested whether there is power on.
A number of voltage detectors have a glass fuse. Often this is the cause of no longer working for returns.
A voltage tester is a two pole tester for AC and DC voltage. A voltage tester is often inspected according to the VDE guidelines.
There are several onion linings:
- Simple voltage tester, + and – current only, range is 120-415 V.
- There are voltage testers with an analogue and with a digital display.
- Advanced testers, for AC and DC voltage with even the possibility to measure stray voltages (stray voltage is a loss of voltage due to poor insulation).
If a voltage tester is broken, it must first be checked whether the glass fuse is broken or whether the battery is empty.
In addition to voltage testers and voltage finders, there are also multimeters
These have many uses. Depending on the type, it must be considered what the applications are and which setting values are possible. In order to use a multimeter properly, they must be set up before use.