How to Cut Finger Joints in Wood

What You'll Need
Router table
All necessary wood
Paper and pencil

If you regularly undertake woodworking projects, you will find that finger joints can help you to create sturdy edges for the item you are constructing. By following a few steps, you can ensure that the task will be undertaken correcly to produce the best possible results.


Step 1 – Preparation

To begin, prepare the wood that you will be fitting together. After they have been measured and cut to the correct size, sand the edges to ensure that they are smooth and ready to be fitted together.

If you are unsure of how wide you want each of the individual fingers of the joint to be, experiment with a piece of paper first. Measure the width of the wood and use this to determine the length of the finger joints. With a straightedge and a pencil, draw a two dimensional outline of the wood so that you can create your design. Do this by measuring the width of the wood and dividing the result by the number of fingers that you desire so that they are equal.

Step 2 – Mark Wood

Next, mark the wood with the design for the finger joints to show where the cuts need to be made. Do this by lining up the pieces of wood so that the edges abut each other. Use the measurements that you have already planned on paper. Use a straightedge to mark a pencil line parallel with each edge at a depth that is equal to the width of the wood. Once these are complete, draw the lines to link up those on the side that will become the edges of the fingers.                  

Step 3 – Test Cut

Undertake a test cut with some scrap pieces of wood, making use of the prepared measurements. Draw out just one tongue and groove to test that the finger joints fit. Position the wood on the table of the router and manipulate the router blade to cut out the lines. Once the cuts along the lines are complete, remove them from the router and manipulate them to make sure that they fit together well.

If you need to make any adjustments, smooth the inner surface with some sandpaper and fit them together again to test whether they fit snugly. This test process will also give you the opportunity to make sure that you are using the correct router bit.

Step 4 – Cut Wood

Finally, you will be able to cut the finger joints in the pieces of wood. Position the wood in the router and clamp it into place. Start at one end of the pencil line and gradually working your way through until you have cut out the pencil lines. Do not allow yourself to be distracted while using the router to ensure that you do not make any mistakes. Tidy up jagged edges with sandpaper once the cutting process is complete.