DIY Basics: Essential Guide To Clamps

The one thing you can be sure you’ll need to do with virtually every DIY project is keep it still and stable while you work on it.

‘Owning a good collection of clamps and a solid vice is like having a crew of reliable helpers on standby to hold something for you,’ says Australian Handyman contributor Gun Arvidssen.

And you will be rewarded with years of reliable service if you buy the best quality you can afford.

‘My dad is still using the same G-clamps he’s had since I was three years old, and they work as smoothly now as they ever did,’ says Gun.

A gripping tale

Although most people are familiar with what a vice does, there is confusion about the difference between clamps and cramps.

It’s not a spelling error, there is a genuine technical distinction between these two different classes of device.

CLAMPS use spring pressure or friction to hold things together. Often designed to be operated one-handed, they offer less power than cramps but are easier to use.

CRAMPS rely on a screw-type mechanism, in the same way as a vice, and are capable of exerting a great deal of force. Sash, pipe, corner, G and F shaped tools fall into this category.

VICES are typically mounted on a workbench. Metalwork vices are usually bolted to the top, and woodworking vices installed into the side of the workbench.

Cramps

In practice, the word ‘cramp’ has mostly fallen out of favour and the majority of DIYers are familiar with the terms that describe the different types of tools, such as F-clamps or bar clamps.

This means a more detailed explanation about the mechanism each clamp uses to exert force is not really necessary.

To avoid overcomplicating things, we will stick to using the same word for both categories.

G-clamp

About as simple as a clamp can get, this comprises a roughly semicircular steel frame with a heavy-gauge threaded spindle that is wound through one end, making it looks like the letter G when open.

The spindle has a disc-shaped swivel shoe mounted at one end, which moves towards or away from the top arm of the G as it is turned with a tommy bar at the other end.

A G-clamp is about as simple as a clamp can get

F-clamp

Less solid than a G-clamp but with more reach, an F-clamp has a similar arrangement to a spindle with a swivel shoe doing the clamping against an opposing frame.

The difference is that the arms are straight instead of rounded, and mounted on a rail which makes them resemble the letter F.

One arm is permanently attached at the end of the rail while the other can slide towards or away from it to suit the size of the workpiece.
When pressure is applied, the movable arm locks against the rail.

The F-clamp has straight arms that resemble the letter F

Long-range clamps

If you need maximum clamping force for a bigger project than even the longest F-clamp can comfortably handle, such as when edge-laminating timber to make a tabletop, sash clamps and pipe clamps will hold it steady and save the day.

A sash clamp is sturdy and gives a flat surface for edge laminating

Pipe clamp

These are usually supplied as a set of clamp heads compatible with standard 19mm steel pipe.

The fixed head winds onto the threaded end of the pipe with a handle to turn the spindle and push a jaw that moves along the pipe.

The movable head is a jaw mounted on a collar that can slide freely along the pipe, with a clutch mechanism to lock it against the pipe.

These clamps are usually supplied as clamp heads compatible with a 19mm steel pipe.

Edge-laminating timber

Pipe clamps and sash clamps are both useful when joining narrow boards edge-to-edge into a larger panel. Use dowels or biscuits and PVA adhesive to secure the boards to one another, then tap in shims or wedges to correct any bowing.

Step 1. Match the grain pattern

Arrange the boards so the grain patterns match as much as possible. If you can, position the boards so the curve of the end grain faces up and then down on alternating boards, marking the alignment with chalk.

Step 2. Set up the clamps

Position pipe clamps or sash clamps on a flat, level surface, applying masking tape to protect them from drips of adhesive. Position lengths of timber to act as buffers between the jaws and the boards then align the marks.

Clamps holding together pieces of timber

Step 3. Laminate the boards

Mark up dowel holes or biscuit slots then apply PVA adhesive and insert the fasteners. Gradually tighten the clamps until adhesive oozes out then use a steel rule to check for any bowing, tapping in shims if needed.

One-handed clamps

This class of device is designed for convenience more than powerful compression. Bar clamps and handy clamps are tightened by squeezing the handles, which also lets you gauge how much pressure is being exerted on the workpiece.

Spring clamps

Similar to oversize bulldog clips, these are about as simple as clamps get. They comprise a pair of springloaded metal or plastic handles that pivot to open the jaws when squeezed together.

They are best for thin workpieces such as plywood or MDF and use spring tension to exert force.

Spring clamps are similar to bulldog clips

Bar clamps

The ultimate all-rounder, bar clamps are fast and easy to use, grip tightly and usually have large jaw faces with buffers that won’t damage the timber.

They are operated by squeezing the handle to advance the bar with a fixed jaw at the end. A smaller trigger catch can be pressed to release the bar and let it slide freely.

TIP Some models even feature an interlocking function that allows them to be used as a temporary vice.

Bar clamps are operated by squeezing the bar advance handle

Locking clamps

Applying point force in a similar way to handy clamps, these are closely related to locking pliers such as Vise-Grips.

The tension and opening width is normally adjusted by turning a knurled screw, then the mechanical strength of the steel frame holds the workpieces with considerable force once the handles are squeezed together into the locked position.

Locking clamps work in a similar way to handy clamps

Handy clamps

Like a hybrid of spring clamps and bar clamps, these are squeezed shut by hand and held by a ratchet.

Pressing the trigger releases the pressure. This type of tool usually has a wide pincer action and a small footprint, making it useful for holding items with an irregular edge that may obstruct other types of clamps.

Handy clamps are like a hybrid of spring clamps and bar clamps

Clever clamping

Get the most out of your clamps with these pro tips and handy techniques that will help you work in awkward spaces, extend the reach of your tools, enable you to accomplish difficult construction jobs solo and protect delicate timber surfaces.

Use clamps as spreaders

Some clamps have a removable jaw allowing them to be used to apply outward pressure from the inside of an assembly or frame.

Reverse clamps, also called spreaders, are perfect for holding things in position when the outside of a workpiece is irregularly shaped or inaccessible. They can also be used for gently jacking apart timber frames to crack dowel joints when restoring old furniture.

Reverse clamps can be useful when restoring furniture

Protect the workpiece

Always position small offcuts of timber, plywood or MDF between a workpiece and the jaws of a clamp.

Buffers spread the clamp’s force over a wider area, which helps with the even distribution of adhesive.

TIP Make a set of buffers by drilling holes in scraps of 9mm plywood and gluing in small neodymium magnets, available from specialist suppliers.

Clamp corners

To make DIY braces, cut the factory corners from a 900 x 600 x 19mm plywood HandiPanel then use PVA adhesive and 30mm x 8g screws to laminate them.

Use F-clamps to hold the braces firmly in opposite corners of a bookcase, cabinet, frame or similar assembly for perfectly square joints.

Achieve perfectly square joints by using F-clamps in the corners

Helping hands

Larger building jobs can be tough if you don’t have another person to give you a hand from time to time.

A few clamps and timber offcuts can save the day. The key is to picture how the other person would hold things for you then emulate that support using mechanical helpers.

Extend pipe clamps

If your pipe clamps aren’t quite long enough for a job, just extend them.

Remove the movable head, wind a threaded coupling onto the end of the pipe and attach a second length of pipe, then replace the head.

TIP This won’t work if you’ve cut the pipe to size, unless the fixed head can be clutched onto unthreaded pipe.

Framing clamps

There is a whole category of tools that are designed to hold lengths of timber at precisely 90º to each other, both for delicate mitred joints such as those used for assembling picture frames and heavier building jobs.

Corner clamp

Typical light-duty corner clamps have a pair of spindle assemblies at right angles to each and also feature a right-angled frame to hold two mitred pieces of timber in precise alignment.

They typically have swivel shoes with a reasonably large surface area to avoid damaging intricately shaped moulding, as well as a generous span to accommodate wide pieces of timber.

A corner clamp will hold two pieces of mitred timber together

Four-way speed clamp

An all-in-one solution for small picture frames, this comprises four threaded rods with L-shaped corner blocks that are tightened against the frame with threaded collars.

A clever design feature is that the collars are often cross-drilled, allowing them to slide along the rods at a slight diagonal, and the thread only engages with the rod when they apply pressure against the L-blocks.

Heavy-duty framing clamp

Heavy-duty framing clamps are available in both external versions that work just like light-duty corner clamps, and also with an internal type action that uses a single spindle to push a right-angled block against the matching frame to grip the timber.

TIP Some types even feature a swivel head that allows them to clamp workpieces of different thicknesses.

Heavy-duty framing clamps work like corner clamps

Band clamp

Another system that uses four L-blocks to apply pressure to the entire frame in one go is a band clamp. This uses a nylon or steel band that can be slid through the clamp until the blocks fit around the frame.

The band is then locked off and a spindle mechanism is used to apply tension to the band, compressing the mitred joints tightly together.

Vices

Engineer’s vice

An engineer’s vice doesn’t have to be used exclusively for metalwork as the name suggests.

It has a solid construction and narrow, knurled jaws designed for gripping metal workpieces. Many are mounted on a rotating base that allows them to swivel through 360º so they can grip the workpiece at the optimal angle.

An anvil is often machined into the back of the vice, or the sleeve over the spindle may be flat for the same purpose.

An engineer’s vice is often mounted on a rotating base

Woodworking bench vice

A woodworking vice has wide, flat jaw faces that are normally pre-drilled so plywood or timber buffers can be secured, lining the metal with a surface that won’t mark or damage the workpiece.

Woodworking vices are recessed into a workbench so the fixed jaw finishes flush with the side, allowing long pieces of timber to be supported along the full length of the bench.
If your benchtop has a skirt or a framework along the edge, simply install the vice behind it.

Install a bench vice

Attaching an engineer’s vice is a simple matter of bolting it onto a benchtop, but woodworking vices should be secured so the fixed jaw is flush with the edge of the bench. Choose fasteners to fit the pre-drilled holes in the jaw faces and bolt lugs.

Step 1. Cut the spacers

Clamp a piece of timber in the vice and adjust it until the top of the jaws are flush with the benchtop. Measure from the underside of the bench to the top of the bolt lugs and cut a 200 x 100mm spacer of the same thickness.

Step 2. Make the recess

Cut plywood buffers to fit the jaw faces and secure with screws. Use a jigsaw to cut a recess in the edge of the bench so the fixed jaw finishes flush, then check that the vice fits snugly and use a file or chisel to enlarge the recess if needed.

Step 3. Bolt on the vice

Clamp the vice in position and use a twist bit to drill four clearance holes through the benchtop and spacer. Use a spade bit to create recesses for the bolt heads then secure with cuphead bolts