Machine Production Techniques - Lesson Nine

This lesson was the start of the table with drawer which we will be making. The lesson was a theory lesson, which explained about the mortise and tenon joints we will be making.

A brief description on a mortise and tenon joint:

• Means of mechanically joining two pieces of wood
• Strong - Only moves in one direction
• CUT MORTISE FIRST!!! - Drill bits at certain widths - difficult to fine tune the width of mortises
• Tenon cut after - easy to fine tune to mortise

Why add shoulders:

Above: Tenon with shoulders

• Prevents racking
• Positive stop location for a tenoned component
• Hides the edges of the mortise

The rule of thirds


Normally for the tenon part of the joint, you divide it by three, and that will determine roughly how big the tenon will be. This may have to be adjusted slightly depending on the cutter.

Above: Rule of thirds

Our Rails:
We are doing the tenons for the table with this specification:

• Split into 4mm, 10mm, 4mm
• Reveal - 3mm
• 37mm maximum length of tenon (Mitred at end - 45 degrees)
• Top shoulder and haunch 10mm
• 150 MAXIMUM tenon length till it becomes forked.

Above: Forked tenon used in leg construction with haunch

Finally in this lesson we looked at the spindle moulder. This is a machine which is used to shape pieces of wood by using a jig. This is what I am going to be using to shape the legs of the table.

Above: Example spindle moulder

A few important rules are that it is a maximum cut of 1.1mm, and to shape the legs you have to have one mortise up and one facing you for the first cut, and then one facing you and one facing down to cut the profile on the outside edges of the leg.