The Three-Way Mitre - Canadian Woodworking Magazine

Finer Details: This classic Chinese joint is a fantastic way to add some class – and difficulty – to your next project.

The Three-Way Mitre

The Three-Way Mitre



Photos by Diane Walsh; Lead Photo by Ray Pilon
Sean Walsh's “Tea for Two” won first prize at the recent Wood Objects Show in Ottawa.


I don’t believe you have to be a master woodworker to achieve beautiful and sound joints. Take your time and pay attention to the details and you will be surprised with the results. Make sure you take the time to consider the order of operations and follow them closely to ensure that the joint fits and looks seamless. I learned how to machine this joint from Yeung Chan at Rosewood Studio. To ensure that all pieces are square, mill all your stock at the same time and take great care when doing so. Give yourself plenty of extra length on your stock for test cuts, and make at least one, if not two, extra pieces just in case something terrible happens. It’s difficult to reproduce a single piece after the fact.

Before setting to work on the actual joint, you will want to make a 45° jig for your table saw. Attach the runner to the underside of the bottom and make a cut on the edge of the bottom by simply running it past the blade. Cut the other piece of plywood so one of its corners measures exactly 90°. Attach it to the jig so it makes a 45° angle with both edges of the bottom.

Set up your table saw with a square top blade that is clean and sharp. Use a square to ensure the blade is set to 90° and don’t assume the gauge on your saw is accurate. The two horizontal rails that make up this joint will be identical, while the vertical leg is slightly different. Make a 45° cut on the end of the rail. Next, rotate the rail 90° and line up your second cut to intersect at exactly the same point. Patience is required for a perfect match. Repeat with the second rail.


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Start With the Rails – With a 45° mitre jig, Walsh makes two identical cuts on the end of each rail. The guard is removed for clarity.

Put the rails aside for now and turn your attention to the leg. With the blade height set to exactly half the height of the stock make progressive cuts to create a shoulder. Rotate the stock 90° and repeat, making sure the cuts line up exactly and form a sharp tip. Finally, with the stock at 90° to the blade, trim the tenon to the point where it meets the apex of the mitre.

You will have to create a pocket in each of the rails to accept the tenon on the leg. I have found that using a sharp chisel is the easiest and safest way. Using a marking gauge, mark the location of the pocket. With your chisel, take small cuts at the point of the pocket and slowly remove the waste. Stay back from your lines at this point and just focus on roughing out the area. Once most of the material is removed, sharpen your chisel to a fine point and, with care, pare the sides to create a smooth and square pocket. Test fit the joint and make fine adjustments if needed.
 

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Next is the Leg – Lower the blade to cut only half way through the stock, leaving a shoulder. Note that the work piece is referenced off the other fence on the mitre jig.

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Work the Shoulder – Cut the shoulder on the leg so its corner meets at the mitred edge.  On the rails a cavity will have to be cut to accept the legs’ shoulder (below).

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Using a marking gauge, make parallel lines on all three parts to define the tenon cavities. Make sure that you are using the outside of each piece as the reference surface. Take your time on this step as this will determine the final placement of each piece and how sturdy the joint will ultimately be. Once you have marked all pieces, put your marking gauge in a safe place and don’t change the setting until you have completed the final assembly; if you have to re-make a part, you will have this dimension to work from. With a combination of a small bevelled edge and paring chisel, create a slot in each piece about ⅛" wide to accept a live tenon. Finally, mill a length of straight grain stock and cut the live tenons.

I strongly recommend doing a full dry run with all clamps, as this will help identify any problems before you apply glue and disaster strikes. Once glued up, you can hand-plane or sand your piece to remove any machine marks.

If you have never attempted this type of work before, make a sample corner. You will quickly realize what aspects are the most difficult for you. In addition, this will give you a sample to use when meeting with prospective clients in the future or to impress your friends.


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Tiny Mortises – All three pieces will have to have small mortises cut in them to help with alignment and strength; a perfect job for a ⅛" wide chisel.

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Three Amigos – After all that hard work, the three pieces should fit together like good friends.

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Photo by Ray Pilon



SEAN WALSH
Sean Walsh