Fitting the Tenon — How to Make a Mortise and Tenon

You can now test your tenon in the mortise to see how far off you are. The benefit of cutting the tenon slightly fat is that you can then trim a little at a time from the cheeks to achieve a good, snug fit. You can simply do this with a sharp 1” (25mm) chisel.

Check it fits. You may not need to pare down the tenon cheeks.

There may be a step down caused when sawing

At this stage, you can use a router plane to ensure that the surface is being planed to the same level. Set the depth of the blade to slightly above the surface of the cheek to remove any protrusions. Keep checking the fit of the joint as you don’t want to take too much off. Make sure you are equal on both sides of the tenon. Lower the blade in small increments until it starts to fit into the mortise.