How to Make Spline Dovetail Joints

Step-by-Step Guide

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   Step 1: Start by making the jig as shown in the picture and drawing.

   Use 18mm MDF for strength, and make sure the included angle is exactly 90 degrees to ensure stability.
   
   The sizes given are advisory; though keep the top plate as large as possible for maximum router support. , It’s a good idea to use biscuits to help hold the joint in alignment.,, Start about 10mm in from each edge for the outside pair, and then divide the space between equally across the joint., Fit the router with a guide bush and dovetail cutter., This should fit snugly in the guide bush groove and have its centre clearly marked.,, Check its alignment again with the setting bar., Set the depth 10mm below this.
   
   Pull the router back, plunge to full depth and lock it down., Switch off without releasing the plunge lock.
   
   Re-set the jig and repeat for all the marked positions across the joint.,, Set a sliding bevel to match its cutting angle., The crown guard has been removed for clarity here, but must always be fitted when using the saw., Prepare a long length; trim it to size later., Lay the timber on its side, and with the blade still tilted, take shaving cuts off the bottom until the piece will just fit into the dovetail sockets., Apply a little glue and gently drive one into place in the first socket with a hammer., Put the joint aside to allow the glue to set., This allows you to trim right up to the edge without damaging the workpiece.,,
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   Step 2: The dovetail splines are inserted through an already assembled mitre joint

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   Step 3: so the first step is to assemble the joint and glue it up.

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   Step 4: Clamp your assembled mitre joint in the bench vice so it faces upwards.

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   Step 5: Mark out the dovetail spacings across the joint.

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   Step 6: See the clearly marked-up work piece is now ready for machining.

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   Step 7: Make a setting bar to help you set up your jig accurately.

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   Step 8: Insert the setting bar through the jig and line it up on the first of the marked lines on the joint below.

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   Step 9: Clamp the jig in place so it fits squarely over the mitred workpiece.

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    Step 10: Stand the router on the jig and plunge the cutter until it touches the joint.

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    Step 11: Start the machine and run it through the joint.

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    Step 12: After machining

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    Step 13: the joint has an evenly spaced series of cleanly-cut sockets.

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    Step 14: Remove the dovetail cutter from the router.

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    Step 15: Transfer this angle setting to your table saw.

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    Step 16: Set the rip fence a little wider than the base of the dovetail

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    Step 17: and rip down both sides of your timber to make the splines.

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    Step 18: Adjust the fit.

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    Step 19: Cut the splines into short lengths.

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    Step 20: Repeat the process for the other sockets.

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    Step 21: Trim off the waste with a flexible pull saw.

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    Step 22: Finally clean up the surface of the joint with fine abrasive paper.

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    Step 23: The finished joint

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    Step 24: with the dark splines contrasting well with the paler wood of the workpiece.

Detailed Guide

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