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Clamps Buying Guide

Clamps are the silent heroes of the workshop. They do not cut, bore, smooth, shape, fix or finish but they hold the workpiece securely so your other tools can. With the dazzling array of clamps available, it can be difficult to choose the right ones for the task in hand. Whether holding pieces together during gluing or as an extra pair of hands in the workshop, clamps are an important part of any woodworker's tool collection.

Anatomy of a Clamp

Anatomy of a Clamp

Despite the many different styles available, clamps all share the same fundamental parts. The work is held between two jaws one of which is usually fixed in position and the other which is moveable.

It is this moveable jaw that is adjusted and tightened to create the desired clamping pressure on the work. There are different methods for tightening this moveable jaw.

Many clamps feature screw threads with a pivoting foot on the end, while other clamps have cam or ratchet activated closing mechanisms.

The jaws are mounted on a bar or beam which gives the clamp its strength when clamping. Some bars have I, T or K profile shapes which gives the bar extra resistance to flex or bending when under load. In the case of C or G clamps, the beam and jaws are forged or cast as a single piece. ©

Types of Clamps

Bar Clamps

Bar clamps are used for clamping edge to edge boards together to create larger panels and for holding together frame assemblies. Comprising of a fixed jaw and a moveable jaw mounted on a profiled metal bar, these clamps are capable of exerting immense clamping pressures. The profile of the bar can be either T or I shaped and this shape makes the bar much more sturdy and flex resistant under load than a simple rectangular profile beam would be. The moveable jaw is normally held in position with a steel pin and a screw thread with a pivoting pad applies the pressure on to the work pushing it against the fixed jaw. ©

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Sash Clamps

Similar to the bar clamp in design and function, sash clamps feature thick, rectangular section bars rather than the I or T profiled bars of the bar clamps. The cross section of the bar is much taller than it is wide giving it good resistance to deforming under load. Used for clamping panels and frame assemblies, sash clamps are used in the same way as bar clamps and excel at clamping panels and large sheet work. ©

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Panel Clamps

As the name suggests, panel clamps are used for clamping large panels such as doors and table tops. Unlike bar clamps, panel clamps exert pressure in two directions not just one. Sideways pressure keeps the boards together for a tight glue line and pressure exerted across the panel prevents it from cupping or warping. Many panel clamp systems are wall mounted for added convenience and this allows work to take up the minimum amount of space leaving benches and tables free for other work. ©

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Parallel Jaw Clamps

Most commonly used for frame assembly, parallel jaw clamps give the very even clamping pressure that is desirable for this kind of work. As the jaws remain parallel to each other throughout clamping, the pressure is distributed equally across each jaw. This eliminates the risk of the frame twisting due to uneven pressure across the jaw. ©

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F-Clamps

So called because of their shape, F clamps offer a longer reach than G clamps when clamping pieces together or anchoring jigs and work to the bench. Featuring one fixed jaw and one moveable one, F clamps are quick to engage and exert high clamping pressures when needed. The jaws usually feature small clamping pads and it is these that contact the work. Due to the small surface area of the pad and the pressure exerted by the clamp, F clamps may indent the workpiece. ©

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G-Clamps

Possibly the most popular clamp in the workshop, G clamps can be used for anchoring a jig or work piece to the bench or tool table as well as for clamping components together. The single piece C shaped body gives the clamp immense strength as it is highly resistant to flexing under load. The clamp is engaged using a screw thread. G clamps do not have a particularly large throat depth when compared to other clamps and for clamping tasks where a longer reach is required, F clamps may be more suitable. ©

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Quick Action Clamps

Quick action clamps are similar to F clamps, however, rather than having a clamping mechanism activated by a screw thread they have a geared mechanism which activates the clamp by pulling or pushing a handle. This makes the quick gear clamps much faster to engage and disengage. The push lever clamps give extra clamping pressure as they allow you to use your body weight to action the clamp. A ratchet inside the clamp keeps it at the desired clamping pressure preventing it from loosening under load. ©

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Clamp Grip Guides

A combination of a clamp and a straight edge, clamp grip guides not only offer the ability to cut straight lines when used in conjunction with a circular saw or a router but can also be combined to hold work when sanding or finishing. Again, featuring both a fixed and a moveable jaw, the clamping action is deployed using a single lever to lock the guide in to place. ©

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Face Clamps

Used for aligning pocket hole joints, face clamps are capable of holding L and T shaped joints in position during fixing. These clamps have narrow metal arms that are angled to reach over the work. Most pocket hole clamps have a large flat face on one jaw and a smaller almost pointed one on the other. This allows them to fit into screw holes to anchor the work more successfully. ©

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Hold Down Clamps

Used in conjunction with a dog hole on a workbench, hold down clamps are designed to push down on the work piece keeping it firmly on the bench. Usually a clamping arm mounted perpendicularly on a metal shaft, hold downs use a combination of weight and friction in the dog hole to hold the work on the bench. ©

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Mitre Clamps

Used for keeping the two faces of a mitre joint together, mitre clamps are ideal for use when making picture and mirror frames, boxes and any other project that requires a perfect 90 degree mitred corner. These clamps hold the two separate pieces firm whilst also pushing them together. ©

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Picture Frame Clamps

Designed to hold a complete frame during fixing or gluing, picture frame clamps exert equal pressure on all four corners of the frame at once keeping the frame square during gluing or fixing. ©

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Strap Clamps

Strap clamps consist of a long, broad nylon or metal strap and a tensioner. This basic design does not restrict the clamp to any particular shape making it ideal for irregularly shaped pieces. The strap simply wraps around the workpiece and is tensioned allowing it to exert equal pressure in all directions on the joints being glued. Perfect for furniture, frames and all kinds of other projects, some strap clamps are supplied with clip on corners for clamping regular shapes such as square or rectangular picture frames. ©

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Toggle Clamps

Toggle clamps are used for keeping a workpiece in position while some operation is carried out on it. Used with pocket hole jigs, coping sleds and other jigs that require on board clamping, toggle clamps are lever operated and deliver high, pin point clamping pressure. Two types of toggle clamp are available, those that exert pressure horizontally and those that exert it vertically. ©

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Features to Consider When Buying a Clamp

Features to Consider When Buying a Clamp

1. Jaws

The jaws are the only parts of the clamp that come into contact with the surface of the wood and are an important consideration when selecting the correct clamp. All of the pressure exerted by the clamp is transmitted to the work through the clamping faces on the jaws. If these faces are small, then the pressure is concentrated to a very small area and this may result in damage to the work if clamped directly. Larger faces are less likely to cause indentations because they spread the pressure over a wider area but do not give the pin point high pressure clamping of the smaller clamp faces. ©

2. Throat Depth

The throat depth of a clamp determines how far the clamp reaches over the work. For narrow work, this is not an issue, however to ensure a more even pressure distribution across the work on wider pieces, the clamp must be able to reach a good distance into the work. ©

3. Mechanism/Action

The clamping mechanism itself has an impact on how much pressure can be exerted on the clamp and also effects the time taken to engage the clamp. Clamps with threaded bar mechanisms can take longer to deploy but the combination of a bar or cranked handle on the thread allows you to screw the clamp up very tightly for very high pressure clamping. Quick action clamps have a lever operated gearing system that pushes the moveable jaw on to the work. The clamp is kept locked by a ratchet mechanism which can be disengaged by squeezing a trigger when you need to remove the clamp. ©

4. Weight

When selecting clamps for a project, it is vital to consider the weight of the clamps you want to use. Smaller or delicate assemblies will require lighter clamps than a substantial item like a panel. If the assembly will be supporting some or all of the clamps' weight then you will need to ensure that this extra force will not cause the assembly to twist or creep. ©

5. Clamping Pressure

Different clamps are capable of exerting different amounts of pressure. The amount of pressure needed depends, primarily, on how well the parts being clamped fit together. A perfectly fitting mortice and tenon joint will require less clamping pressure than an edge to edge joint and this is reflected in the clamps you would use for the tasks. ©

Tips From the Experts

1. When gluing edge to edge boards for panels, alternate the clamps under and over the assembly. This evens out the clamping pressure and eliminates the risk of the panel cupping. ©

Alternate Clamps

2. Use a clamping square to keep a 90 degree corner at the correct angle when clamping and gluing. ©

Clamping square

3. Use blocks of scrap wood between the work and the clamping faces when clamping with G and F clamps. This will spread the pressure out over a larger surface area and eliminate the risk of indenting the work. ©

4. Never attempt to assemble and clamp a complex project in one go. Split it up into sections and glue and assemble it in sections. Keeping two glue joints aligned is far easier than keeping eight or nine aligned. ©

5. Before clamping and gluing attempt a dry assembly, this will highlight any problems that need solving. There is nothing worse than attempting to assemble a glued up project only to find it will not fit together properly. ©

Brands

Dakota

Dakota tools are sourced from some of the world's best tool manufacturers. Carefully selected by a panel of woodworking experts, each tool is inspected and rigorously tested. Only those tools that meet or exceed expectations are approved to bear the Dakota brand name. Offering a wide range of woodworking products, Dakota's mission is to provide high quality tools to all abilities of woodworker from the weekend home woodworker to the professional carpenter.

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Maintenance

Maintenance

Ensure jaw faces and clamp pads are clean and free from any glue residue before and after use. ©

A light coating of tool oil on cast iron clamps will protect them from rust. ©

Keep clamp mechanisms, clutches and screw threads clean and free from debris. ©