A WOODWORKERS DIARY
Beautiful locked fingers
Denis Lock describes how to cut a finger joint
I
was recently approached by a beekeeper for help with building wooden beehives. A beehive is basically a box and requires four corner joints. The preferred joint (see main photo above) for exterior use is a finger joint (also called a box joint or comb joint). It consists of a series of interlocking fingers that give the joint a high degree of mechanical strength. More importantly, the faces of the fingers (marked with an ‘F’ in the photo) provide face-grain-to-face-grain gluing areas. Collectively this is a large area and after gluing the resultant joint is very strong. The joint is a little tricky to make, but there is no doubt that this is one of the strongest ways to build a box. If accurately cut and glued with waterproof glue, the joint will not fail prematurely. I had been meaning to make a jig to cut finger joints for some time and this request was the impetus I needed. I set out to build a simple but accurate jig. There are basically two ways to machine cut (I wouldn’t try by hand) a finger joint. The first is on a table saw fitted with a dado stack. The second is using a router table: This gives cleaner cuts in the same amount of time. I selected the
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JANUARY 2014 THE HOME HANDYMAN
Guides
2
Sled
latter. My router table jig consists of three components: A sled with a backing board, a pair of guide strips which are clamped to the router table and a facing board (one for each finger size) which incorporates the allimportant indexing key. The sled is a 400mm x 400mm piece of 6mm MDF. The backing board is a 400mm x 120mm piece of laminated chipboard
3 attached to the one edge of the sled. I used a pair of brackets and screws (see photo 2). Two M6 wood inserts (often abbreviated to ‘woodsert’) are fitted to the back inside face of the backing board. These are used to attach the facing board. A pair of M6 T-nuts would work equally well. The two guide strips are 100mm wide pieces of 6mm MDF cut to the width of