kitchen fitters in london especially should be performing invisible joints, instead of using metal strips, a good quality worktop jig which is used to guide the router along the worktop in a specific way and a good quality router with a 30mm collar and long shank 12.7mm cutter will be needed. These specialist tools can be hired from a tool hire shop or if you are a keen or professional carpenter they can be bought at any good tool shop or online.

Most worktop jigs do not come with any form of instructions and those that do are little more than an explanation about which hole does what, but further instructions on their use are available.

To find the point where the joint starts, put the first piece of worktop in position, and then lay the second piece on top in the correct position.

The two worktops will cross over each other at the postform edge and this is the start of the cut. Place a piece of masking tape on the first worktop so that the position of the crossover can be transferred onto the masking tape.

If there is enough worktop it is best to cut them slightly long, in case they get damaged and need to be re-trimmed after the joints are done.

Wherever possible it is best to start from the left to do the butt side of the joint so that the piece to be scribed is on top, allowing the pencil marks to show easily on the underside.

Align the worktop jig up to the pencil line, as the jig instructions show or if no instructions are available then a complete guide and DVD may be found online.

When the first piece of worktop has received the first cut the second piece is placed on top so that it can be marked with a sharp 2h pencil. Mark two points along the cut to show where the cut has to take place.

The worktop is placed upside down on the workbenches to be able to see the two lines previously drawn.

A short explanation about the router. A 12.7mm router cutter with a long shank is fitted into the router. On the base of the router is placed a collar which is 30mm in diameter - this is used as a guide to fit into the 30mm slot in the worktop jig.

The worktop jig is designed to take up the difference between the 30mm collar and 12.7mm cutter. This difference is approximately 8.5mm so wherever we want to use the worktop jig we mark a line, then set the worktop jig up 8.5mm back from the line so that the cutter ends up where we want it.

To cut through those lines that were made when underneath the worktop, 8.5mm needs to be measured back so that the cutter follows the line when using the worktop jig.

A point to make about the worktop jig is that there are strategically placed holes to take pins to allow several uses of the jig. The pins rest against the edge of the worktop and then the worktop jig is clamped in place.

When both sides of the joint are complete lift the worktops into place and close the joint to make sure it is OK. There is little room for error and you sometimes only get one chance to get it right. If the kitchen is being tiled you will have around 5mm of cover so if you make a mistake you can trim up to 5mm off the joint so long as the length of worktop was tight to begin with.

When the joint is cut and fits well it will need to have slots cut underneath to enable 3 bolts to be inserted to allow the joint to be glued with a silicone sealant and clamped tightly by turning the nut on bolts drawing the joint together.

The worktop jig has 3 slots to put in place underneath the worktop to enable the bolt hole slots to be machined, but care must be taken that the correct depth is set on the router or else there is a risk of plunging through the face of the worktop.

It is now a case of trying the joint together and when you are happy with the result then it can be glued and refitted.