Dave's Highboy (continued)
The creation of the timbers
Now we drill the mortises (the holes to fit the tenons in). A hole saw is used to define the outer edges of the round mortise. Since we need to create mortises at right angles to each other, the post is left clamped in a jig. Notice the end of the jig is vertical. Now look at the next picture...
Here the has been rotated exactly 90 degree and clamped to the fence. This ensures the next mortise will be 90 degrees to the first one.
Now, most of the waste inside the mortise is drilled out with a large Forstner bit...
to the depth of the mortise.
The material not removed by the Forstner bit is removed with mallet and chisel. Thus we have created round tenons and corresponding mortises at 90 degrees to each other.