Clamping Techniques

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Unless you are using impact adhesive, you should cramp the wood as soon as the joint has been made. Whichever type of cramp you use, you must be careful that the surface of the wood does not get scratched and damaged by the action of the cramp while the glue is setting. You can either use some newspaper or alternatively, to prevent the metal cramp jaws from bruising the surface of the wood, ensure that there is a small block of wood between the two (fig. 3). Make your blocks, or cushions, from off cuts.


Fig 1. Mix glue to the right consistency, if necessary, then apply it with a stick or straight from the glue bottle onto the surface of the wood.
Fig 1. Mix glue to the right consistency, if necessary, then apply it with a stick or straight from the glue bottle onto the surface of the wood.
Fig 2. With the wood on the bench, wipe off any excess glue to prevent it staining and place the wood in whichever cramp you are using.
Fig 2. With the wood on the bench, wipe off any excess glue to prevent it staining and place the wood in whichever cramp you are using.
Fig 3. Place a block of wood between the wood you are gluing and the cramp to cushion the work and protect it while it is in the cramp.
Fig 3. Place a block of wood between the wood you are gluing and the cramp to cushion the work and protect it while it is in the cramp.

When using a G cramp, make sure that the jaws and cushions are posi­tioned as far over the joint as possible (fig. 3) then tighten the cramp to finger-tight. Where two pieces of angled, or wedge-shaped, wood are being cramped, position a second cramp at right-angles to the first (fig. 5) to stop the parts slipping.


Fig 4. Tighten the cramp and if any excess glue is squeezed out of the joint wipe it away. Leave the wood in the cramp for the required time.
Fig 4. Tighten the cramp and if any excess glue is squeezed out of the joint wipe it away. Leave the wood in the cramp for the required time.
Fig 5. If cramping wedge shaped pieces of wood together, use a second cramp at right angles to the first to stop the wood slipping.
Fig 5. If cramping wedge shaped pieces of wood together, use a second cramp at right angles to the first to stop the wood slipping.
Fig 6. If Gluing long pieces of wood, use several sash cramps on alternate sides. Protect it with cushion blocks on the ends and paper under the sash bars.
Fig 6. If Gluing long pieces of wood, use several sash cramps on alternate sides. Protect it with cushion blocks on the ends and paper under the sash bars.


Use a sash cramp (fig 6) in the same way as a G cramp. Make sure the sash is exactly square to the work piece or distortions may result. If you use an aluminium sash the bar of the sash may tend to bow in towards the work piece under large pressure, so place small wedges underneath to keep it straight. Place paper between the sash bar and the wood to prevent glue sticking to the cramp, if this occurs damage to the wood may occur when removing the cramp. Remember to alternate the grain of the wood as in the example below to stop warping or cupping later on. This is best done before placing the wood into the cramps as it is easier to sort and mark which edges go together on a flat surface before setting up the cramps.

To glue long pieces of wood, place the bottom cramps along the length of the job about 1 metre apart (with paper over the bar) and they must be on a level surface, adjust the cramps to the size of the timbers about to be glued, allowing for the cushion blocks. Glue the wood edges in the cramp by lifting each piece and gluing separately along the edges. Tension the cramps so the timbers comes together under medium pressure and wipe off any glue that has squeezed out. Now place the top cramps centrally between the bottom cramps and tighten all the cramps to the correct tension required. Allow the correct amount of time for the glue to dry before removing the cramps.

When using a web cramp (fig 7), or its improvised alternative (fig 8, 9), ensure that the webbing runs around firmly fixed parts of the work piece. Otherwise, you may break one joint as you are trying to cramp another. If you are making an improvised web cramp, make sure that it is of a really strong material like polyester or nylon cord or even a old car seat belt will do.

Fig 7. For light or medium weight gluing jobs use a web cramp. Run the webbing through the ratchet and tighten steadily.
Fig 7. For light or medium weight gluing jobs use a web cramp. Run the webbing through the ratchet and tighten steadily.
Fig 8. Make an improvised web cramp using strong cord and a short piece of dowel. Use double thickness cord around the object being glued.
Fig 8. Make an improvised web cramp using strong cord and a short piece of dowel. Use double thickness cord around the object being glued.
Fig 9. Use the dowel to twist the strands together untill the tension cramps the wood firmly. Use a second piece of dowel to hold the first.
Fig 9. Use the dowel to twist the strands together untill the tension cramps the wood firmly. Use a second piece of dowel to hold the first.
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