Using a worktop mitre jig to cut kitchen worktops takes time and practice. Don’t think for one minute you can fit your very first bathroom or kitchen and get perfect looking joints in your worktops without a little practice. It may be a good idea to use your old worktops that you are throwing away and practice. Worktop mitre jigs can be bought from many online tool shops or you can hire them from a local hire shop. They are made to fit all different worktop widths and depths. The cutting itself is done with a router to get a clean and accurate cut. There are 2 different cuts that make a mitred joint. The female cut is the cut which is made in towards the centre of the worktop from the front edge of the worktop. The male cut protrudes from the front edge.
The worktop jigs are universal for cutting both ways by simply turning them upside down. The instructions for each cut are always placed in the face you need to be using and each hole or slot is marked for its appropriate use. It makes no difference whether you make the male or female cut first.
Securely clamp the worktop down onto a bench using clamps. You must make sure it doesn’t move at all when cutting or it will throw the joint out of square. The joint you are going to cut needs to overhang the surface you are securing to. The image on the left shows a jig over a worktop ready for the female cut. Push the jig pins into the holes marked Front. This is shown as two red dots on the diagram. The jig is then pushed up to the front edge of the worktop. The pins ensure the cutting slot is the correct distance back from the edge for the cut. Many jigs will accommodate different widths of the worktop. Most worktops are 600mm in width as this is the standard kitchen size so if you have a jig for more than one width a pin or pins must be placed in the 600mm hole.This is shown by the right-hand red dot. It is very important to have a perfect right-angled cut on your worktop before you place the jig. The pins now allow the jig to be placed in the correct position for the cut. Clamp the jig securely into place making sure the clamps are not in the way of the router when you start cutting.
Set your router up with the correct blade and cutting guide. The guide is usually 30mm. We suggest a 12mm router of minimum 1600W. The guide bush sits into the slot in the jig and you start your cut with the bush pressed against the edge of the jig slot which is furthest away from the centre of the worktop. On many jigs, this edge is marked “Rough cut”. On a 40mm thick worktop, you should make a minimum of 4 passes with the router which means setting your router to a depth of 10mm maximum. Do not attempt to take off too much or the blade will get stuck. When you have cut through the worktop on a rough cut, your final pass should be made with the guide or bush pressed against the edge nearest the worktop. This is the clean cut edge and this pass will take the last few mm off to give you a neat cut.
Always start your cuts at the front of the worktop, i.e. the left-hand side.You are now ready to turn the jig over, or round, to make the male cut. Use the pins as marked on the jig and follow the same procedure.
Once both halves of the joint are made you can now choose to clamp the joints together if you wish. If the joint sits onto the top of a unit many fitters prefer to lay the worktop in two halves, pushing the joint together using adhesive and then screwing it tight up through the unit below. It is possible however to clamp the joint tight before placing the worktop or, if the area under the joint is clear, eg for a dishwasher, the joint can be clamped in place. We do not, however, recommend an unsupported joint.
Clamp the worktop face down to use the router to cut out for the holes to take the worktop bolts (shown left). Clean the workbench properly first. The instructions for the clamp slots are on the jig. As before double check, the worktop is secure and don’t attempt to cut off too much at once. If you do you may ruin all the good work you have already done by ruining the worktop or breaking a blade.
And there you have it. Professional looking mitres without the cost or hassle of getting an expert or tradesman in.