Corner Clamps

About Corner Clamps

Corner clamps are essential workshop tools designed to hold two workpieces at precise right angles whilst you join them together. Whether you're assembling picture frames, building cabinets, welding metal fabrications, or creating box joints, a quality corner clamp ensures your work remains perfectly aligned during gluing, screwing, nailing or welding. Also known as angle clamps or mitre clamps, these versatile tools eliminate the frustration of trying to hold pieces in position with one hand whilst fastening with the other, dramatically improving accuracy and efficiency in both professional workshops and home DIY projects.

The category encompasses several distinct types to suit different applications. Standard corner clamps are ideal for woodworking projects, featuring adjustable jaws that accommodate various material thicknesses and secure workpieces firmly during assembly. Band clamps offer an innovative solution for frame-making, essentially combining four corner clamps into one adjustable system that wraps around rectangular or square frames. For metalworking and fabrication, specialist welders angle clamps feature robust all-metal construction with copper-plated threads and heat-resistant components that withstand welding spatter and high temperatures without damage.

Leading manufacturers including Bessey, Sealey, DeWalt, Stanley and Record offer corner clamps in various capacities and configurations. From compact clamps for delicate picture framing to heavy-duty welders clamps capable of handling substantial steel sections, there's a solution for every trade and application. Many models incorporate additional features such as quick-release mechanisms, integrated measuring guides, and multiple clamping points to enhance versatility and ease of use on site or in the workshop.

Jargon Buster

• Mitre Joint: A corner joint where two pieces are cut at 45-degree angles and joined to create a 90-degree corner, commonly used in picture frames and skirting boards. Corner clamps hold these angled cuts perfectly aligned during assembly.
• Butt Joint: The simplest woodworking joint where the end of one piece meets the face or edge of another at a right angle. Corner clamps prevent movement whilst screws or dowels are inserted.
• Band Clamp: A type of corner clamp featuring a continuous adjustable strap or band with four corner pieces, designed to apply even pressure around the entire perimeter of rectangular or square frames simultaneously.
• Welders Angle Clamp: Heavy-duty metal corner clamps specifically engineered for fabrication work, featuring copper-plated threads and heat-resistant construction to prevent weld spatter adhesion and heat damage.
• Jaw Capacity: The maximum thickness of material that can fit between the clamp's jaws, typically measured in millimetres. This determines the size of workpieces the clamp can accommodate.
• Clamping Pressure: The amount of force the clamp can apply to hold workpieces securely. Adjustable pressure prevents damage to delicate materials whilst providing sufficient grip for demanding applications.

Who Uses Corner Clamps?

Corner clamps are invaluable tools for a diverse range of trades and applications:

• Carpenters and Joiners: Essential for assembling cabinets, boxes, drawer units and furniture components with perfect right angles
• Picture Framers: Critical for creating professional mitre joints in picture frames and mirror surrounds
• Welders and Metal Fabricators: Use specialist welders clamps to hold steel sections at precise angles during tack welding and full welding
• Shop Fitters: Rely on corner clamps for assembling display units, shelving systems and custom retail fixtures
• Kitchen and Bathroom Fitters: Use them when assembling flat-pack units and creating bespoke cabinetry on site
• Set Designers and Theatre Technicians: Employ corner clamps for building stage flats and scenery frames quickly and accurately
• DIY Enthusiasts: Home improvers use corner clamps for countless projects from building shelves to creating wooden planters
• Model Makers: Precision corner clamps help create accurate scale models and prototypes
• Window Fitters: Use angle clamps when assembling or repairing timber window frames

How to Choose the Right Corner Clamps

Selecting the appropriate corner clamp depends on several key factors:

Application Type: Determine whether you need clamps for woodworking, metalworking or general assembly. Welders angle clamps with copper-plated components are essential for fabrication work, whilst standard clamps suit most carpentry and joinery applications. Band clamps excel at frame assembly where even pressure distribution is critical.

Material Capacity: Check the jaw opening capacity to ensure the clamp accommodates your typical workpiece thickness. Most models handle materials from 10mm to 100mm thick, but heavy-duty versions offer greater capacity for substantial sections.

Build Quality: Professional tradespeople should invest in robust clamps from reputable brands like Bessey, DeWalt or Sealey. Cast aluminium or steel construction provides durability for daily site use, whilst budget options may suffice for occasional DIY projects.

Clamping Mechanism: Quick-release mechanisms save time on repetitive tasks, whilst fine adjustment screws offer precision for critical work. Swing jaw designs provide versatility when working with irregular shapes or angled components.

Portability Requirements: If you work across multiple sites, consider lightweight aluminium clamps or compact designs that won't overload your van. Workshop-based users can opt for heavier, more substantial models that remain in situ.

Quantity Needed: Frame assembly often requires multiple clamps simultaneously. Multi-piece sets from manufacturers like Faithfull or Sealey offer better value than purchasing individual units, whilst band clamps provide an all-in-one solution for box and frame projects.

Popular Accessories

• Quick-Grip Bar Clamps: Complement corner clamps by providing additional pressure along workpiece edges during assembly
• Clamp Pads: Protect delicate surfaces from jaw marks and distribute clamping pressure more evenly
• Wood Glue: PVA and polyurethane adhesives work alongside corner clamps for permanent woodworking joints
• Pocket Hole Jigs: Combine with corner clamps for creating concealed screw joints in cabinet construction
• Digital Angle Finders: Verify precise 90-degree angles before final clamping and assembly
• Mitre Saws: Cut accurate 45-degree angles that corner clamps then hold during joining
• Welding Magnets: Work alongside welders angle clamps to provide additional holding force for metal fabrication
• Engineer's Squares: Essential for checking right angles before applying clamping pressure
• Workbenches and Saw Horses: Provide stable platforms for clamping and assembly operations

Safety Information

Whilst corner clamps are relatively safe tools, observe these precautions to prevent injury and ensure optimal results:

Secure Workpieces Properly: Ensure materials are fully seated in the clamp jaws before tightening. Insufficient engagement can cause workpieces to slip under pressure, potentially causing injury or damaging your project. Always apply clamping pressure gradually and check alignment before proceeding with drilling or fastening.

Welding Applications: When using welders angle clamps, verify they're rated for high-temperature applications before striking an arc. Position clamps away from the direct welding zone where possible, and allow adequate cooling time before removal. Always wear appropriate welding PPE including gloves and face protection. Ensure your workspace complies with HSE guidelines for hot work activities.

Avoid Over-Tightening: Excessive clamping pressure can crush soft materials, crack joints, or deform thin sheet materials. It can also damage the clamp's threads or adjustment mechanisms. Apply only sufficient pressure to hold workpieces securely without causing deformation.

Stable Work Surface: Always use corner clamps on stable benches or work surfaces. Unstable setups can topple during assembly, causing injury or damage. Secure the clamp assembly to your workbench where appropriate to prevent movement during fastening operations.

Frequently Asked Questions

What's the difference between a corner clamp and a mitre clamp?

The terms are often used interchangeably, but technically a mitre clamp is specifically designed for 45-degree mitred joints (like picture frames), whilst corner clamps can accommodate both mitred joints and straight butt joints at 90 degrees. Most modern corner clamps offer versatility to handle both joint types effectively.

Can I use standard corner clamps for welding?

Standard corner clamps aren't suitable for welding applications as the heat and spatter will damage plastic components and cause metal threads to seize. Always use specialist welders angle clamps with copper-plated threads and all-metal heat-resistant construction for fabrication work. These are specifically designed to withstand the demanding conditions of welding environments.

How many corner clamps do I need for a picture frame?

For a traditional picture frame with four corners, you theoretically need four individual corner clamps—one for each joint. However, a band clamp (frame clamp) provides a more practical solution as it functions as four corner clamps in one system, applying even pressure to all four corners simultaneously whilst keeping the frame square.

Will corner clamps work with thick timber sections?

This depends on the jaw capacity of your specific clamp. Most standard corner clamps accommodate materials up to 50-70mm thick, whilst heavy-duty models and welders clamps can handle sections exceeding 100mm. Always check the manufacturer's specifications for jaw opening capacity before purchasing to ensure the clamp suits your typical workpiece dimensions.

Do I still need to check for square when using corner clamps?

Yes, absolutely. Whilst corner clamps hold workpieces at approximately 90 degrees, you should always verify the angle with an engineer's square or digital angle finder before final fastening. Workpiece irregularities, clamp wear, or incorrect positioning can result in slightly out-of-square assemblies. Taking a moment to check ensures professional results every time.