Clamps
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Clamps
EXPERT KNOWLEDGE FORCE
What different clamps are there?
A basic distinction is made between one-handed clamps and screw clamps. However, as is so often the case, these two designations are not enough. This is because synonyms and specifying terms are often used for one-handed clamps. For example, one-handed clamps are often referred to as clamps or glue clamps. Small clamps, on the other hand, are also called spring clamps. Terms such as clamping clamps are often used as a generic term and therefore synonymous with simple clamps. Finally, there are also wooden clamps which, depending on the version, can be screwed or clamped using a lever. The joint clamp is primarily used for gluing board surfaces. The clamping pressure is built up at the end of the rail via a spindle.
For the sake of simplicity, let's stick with one-handed and screw clamps and take a closer look at their design:
As the name suggests, one-handed clamps can be operated with a single hand. Sizeable models of these clamps are equipped with two clamping arms (jaws), which in turn are connected to a guide rail. To clamp workpieces, pull the movable arm towards you. Clamping can be controlled using a lever that pushes the movable jaw in the direction of the fixed jaw. Smaller one-handed clamps, the spring clamps, often consist of just two clamping arms. A strong spring gives them their clamping force. These generally smaller clamps are also often referred to as clamps or tensioners.
Screw clamps also have two clamping arms and a rail. In contrast to one-handed clamps, however, a threaded spindle runs through the movable clamping arm. The spindle can be tightened using a wooden or plastic handle attached to the lower end of the spindle. This allows the movable arm to be precisely adjusted.
What does the "span" mean for clamps?
One of the most important criteria for all types of clamps is the clamping width. The clamping width results from the Length of the guide rail of a clamp. It provides information on how thick the workpieces to be clamped can be in total. However, the clamping width does not provide any information about the force or pressure of a clamp. Depending on the quality and Material of the components of a clamp, a small clamp can build up significantly more force than a clamp with a very large span. If the clamping force of a clamp is specified at all, it is usually in the range of 50 to around 200 kg.
Many brands offer clamps with a wide range of clamping widths. Bessey, for example, produces screw clamps with a clamping width of 100 mm. However, it also offers clamps with spans of 800 mm or more. Clamps of this size are suitable for assembling furniture bodies, for example, while small spring clamps from Bessey have spans of around 70 mm. They are particularly popular for gluing wooden workpieces, for example.
Clamping elements are a speciality with which you can theoretically produce clamps of unlimited length. The highlight is that you can insert the guide rail yourself and thus influence its clamping width. The clamping elements from Pony or Otoro use a normal 3/4 inch water pipe with a Double bevel thread as the guide rail.
Door tensioners, also known as frame tensioners, also have a large clamping width. These are primarily recommended when high pressure is to be applied - for example when gluing door frames or stair treads. If you are installing doors, you may need a door chuck clamp - which is also often referred to as a door clamp.
What does the term "Throat depth" mean for clamps?
In addition to the clamping width, you may also come across the term Throat depth when researching clamps. This means nothing more than the clamping depth. In contrast to the clamping width, it refers to the Length of the clamping arms.
The throat depth of a clamp is therefore information about how far the clamp can be positioned from the edge of a workpiece. In other words, it describes how far you can guide the jaws of your clamp over workpieces. Most spring clamps, for example, only have a small throat depth. Straight throat depth of just 20 mm is possible here. Sizeable clamps, on the other hand, usually have a throat depth of over 100 mm and sometimes up to 500 mm.
In addition to the throat depth, the protective caps or pressure discs at the pressure points of a clamp also determine how precisely workpieces can be fixed. You can use several clamps to distribute the contact pressure on the material more evenly. Alternatively, flat and stable wooden slats that have been sawn to size can also be clamped between the pressure disc and the workpiece.
One-handed clamp or screw clamp - are there differences other than the operation?
Of course, operation is not the only difference between the two types of clamps. There are several other features that distinguish one-handed clamps from screw clamps :
- Clamping with a one-handed clamp is quicker than with a screw clamp. After all, you don't have to labouriously turn a thread until the clamping jaws exert the right force. Some craftsmen therefore also call one-handed clamps quick-clamping clamps.
- However, screw clamps generally allow significantly more pressure to be applied than one-handed clamps.
- A malleable cast iron screw clamp or an all-steel screw clamp, for example, also enables more precise clamping work. All-steel clamps have elastic fixed and sliding brackets. This means that vibrations have a significantly lower impact on the clamping force. With a malleable cast iron clamp, on the other hand, a particularly high clamping force can be achieved through rigid clamping.
- Finally, only some screw clamps allow the lower arm to be repositioned without tools. This means that workpieces can not only be clamped, but also internally chucked.
Tips for using clamps
- Use a gluing aid that allows you to have both hands free to apply clamps and fixtures.
- Avoid turning the spindle of a screw clamp as far as it will go when fitting it - this is usually the result of opening it too far last time.
- Distribute the pressure of a single clamp over a square timber and two clamps over a wider area.
- You can connect two clamps to form a Length double clamp: Hook the fixed clamp arms into each other.
- To free your hands for setting a larger clamp, you can first use External chucking. Once the individual workpieces and fixtures are aligned, you can use both hands to attach the screw clamp.
- Clean your screw clamps after each use.
- Remove dried glue crusts by wrapping the areas with a cloth soaked in vinegar essence and soaking for around two hours. The crusts can then simply be wiped off.
- Do not store your clamps in a criss-cross pattern in a drawer. Use clamp holders. Not only will this protect your clamps from unnecessary damage, but they will also always be within easy reach. You can find even more information and tips on using clamps in the blog post The right clamp for every purpose.