Through Mortise & Tenon

One of the most common joints in woodworking and is used in our Shaker Style Step Stool.

Step 1: Measure & mark out Tenon

On the end grain, mark out the size of the tenon. The waste surrounding the tenon should be of appropriate measurements for the chisels. Extend the lines to all 4 sides.

The height of the tenon is slightly greater than the thickness of the mortise piece – to avoid a sunken tenon. Mark on all 4 sides of the tenon piece.

Step 2: Saw along markings

Fasten the tenon piece vertically and do not exceed the lines defining the height of the tenon.

Step 3: Cross-Saw to reveal Tenon Shoulders

Brace Tenon piece horizontally against a holdfast or a stop block. The waste material should fall off revealing a step, also known as shoulders, on all 4 sides of the workpiece.

Step 4: Cleaning up Tenon Shoulders

Place scrap pieces of wood below the Tenon for stability. Align the chisel’s cutting edge on the line defining the tenon’s height. Chop to refine the tenon shoulders. Repeat this process on all sides.

Step 5: Pare Tenon shoulders

A slight hill rising towards the tenon may remain after step 4 (this happens if the chisel was not fully perpendicular). Pare this excess down and repeat on all 4 sides.

Check the flatness of a shoulder using a try-square or the length of a chisel. Ideally, the try-square or chisel should not rock from end to end of the tenon’s shoulders.

Step 6: Pare Tenon

Repeat step 5 for the Tenon. This means ensuring that the top of the tenon is square with the base (where it meets the shoulders).

Step 7: Measure and mark out Mortise

Measure the dimensions of the tenon’s shoulders using the Vernier Caliper depth gauge to mark the Mortise. Alternatively, secure the tenon perpendicular and flush against the mortise piece to trace.

Mirror the measurements on the opposite side for easier reference.

Step 8: Lay down Knife Line and start Chopping

Lay down a knife line outlining the mortise. Chop from one end of the mortise to the other. Repeat to remove bulk material.

Step 9: Clean up Mortise

Chop or pare excess material down to the drawn line on all edges until flat.

Step 10: Fitting the joint

Being able to fit the joint halfway by force of hand alone indicates a good fit. The remainder can be tapped flush with a hammer or mallet.

Otherwise, check the tenon for burnish marks, which will indicate the points of unevenness – repeat checks for flatness, pare any excess before re-attempting the fit.

Step 11: Inserting wedges

Once the joint fits well, remove the tenon piece and secure it perpendicular to the workbench.

Make a top-down cut which will divide the tenon in two, being careful not to exceed the shoulders. This creates the slot for a wedge.

Re-insert the tenon and tap a wedge of equal width into the slot using a hammer. Once tightly secured, apply some glue and allow it to dry.

The excess material from the wedge can subsequently be sawn off. If the tenon juts out from the point of exit on the mortise, simply plane it flush.

1. Introduction to Woodworking Tools

Begin your journey with a clear understanding of the features and safety aspects of your tools.

2. Basics to Tool Maintenance

The next step to achieving great success is ensuring your tools are performing at its best.

3. Basics of Joinery

A continuation to your woodworking journey that brings you close to a furniture project.


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