The type of cramp you should use depends on the size of the wood you are gluing. Remembering that there are many different kinds of cramps, we will be dealing here with only a few that should cope with most jobs that you will encounter in carpentry. For a full run down of cramps see Types of Clamps or Cramps

[edit] G Cramp

Sometimes also known as a C-cramp, this most versatile type of cramp gets its name from its shape. G cramps have a mouth capacity of between 25 mm and 250 mm or 300 mm and are mainly used for cramping pieces of wood to a bench and for holding down veneer or laminate while the adhesive dries. Variations on the basic G cramp include deep-mouthed cramps which reach further across the work piece and small, sliding bar G cramps. The latter are smaller and easier to use than conventional G cramps and are useful for holding small pieces of timber in place.

[edit] F Cramp

The F Cramp is just like the G Cramp taking its name from it’s shape and has the same uses as the G cramp, but has a greater mouth capacity ranging from 25 mm through to 1200 mm. Because of this it becomes a very handy cramp to have in the workshop, having a larger variety of cramping jobs that it be use for.

[edit] Sash cramp

Sash cramps are used to cramp larger pieces of timber, such as doors and window frames. Consisting of two adjustable stops on a long bar, they come in different lengths up to 3m long with extensions. One stop is adjusted by sliding it along the bar and securing it with a pin: the other tightens like a vice jaw. Because of their size, sash cramps can be expensive to buy. They are, however, obtainable from all good hire shops.

[edit] Web cramp

This' consists of a long loop of nylon webbing, running through a ratchet, which can be tightened and released using a spanner or screwdriver. The web cramp cannot apply as much pressure as a sash cramp, but it is cheaper and is quite adequate for light and medium weight gluing jobs. You can make an improvised form of web cramp by using strong cord and two short pieces of dowel. Tie a double thickness of the string around the object to be put under pressure then use the dowel to twist the strands together until the tension cramps the wood firmly. Use the second piece of dowel to hold the first in place.