How to make a mortise and tennon joint...

Step 1 is to mark out the mortise. Generally when mortise and tennon joints are made - the tennon is made to fit the mortise. To mark this out I used a small try-square and my marking gauge.
Remove the bulk of the material using a drill bit. I used a flat bit in my drill press. This bores flat and accurate holes. You can do this with a hand held drill though - if you do this take care to keep it straight. You can also get dedicated mortising machienes which cut square holes. These consist of a square hollow chisel with a drill inside.
Remove the bulk of the material with a drill bit. Clean the mortise up with a sharp chisel and make it square.
Now we have finished making the mortise it's time to craft the tennon. First of all work out the measurements of the mortise (Depth, Length and Width) and set up a marking gauge. Using the marking guage scribe the lines where the shoulder and cheak cuts will be.
This is how the timber should look when you have finished laying out the tennon. Now it's time to go over to the tablesaw and cut the tennon.
I've set my tablesaw accurately to cut the tennon.

I've set up an auxillary fence before the blade attached to the rip fence the correct distance away from the blade to ensure that the wood is cut accurately. I'm using the mitre gauge set at 90 degrees to the blade to guide the wood through. To make the tennon I used a process know as 'nibbling' - this is then you make pepetative cuts to remove alot of material.

When using a tablesaw wear eye protection, dust mask and ear defenders.
Remove and defects or burrs of wood and generally clean the tennon up using a sharp bevel edge chisel.

This is the finsihed tennon.

The moment of truth...does it fit ?

Of course it does - Like a glove
Once glued and clamped we have and almost indestructible joint which has many uses and will take alot of stress and last for years.