To make mortises, to make mortise and tenon wood joints, we can use a mortising machine, a router and a mortising jig or a table saw jig. Or we can also use a chisel to make them by hand. There are also mortising attachments that we can use on the drill press. But here we’ll see how to use a simple drill bit to make that task. So I’ll only need my drill press, a simple wood drill bit and my drill press table.
First I must decide where to make the mortise and tenon joint.
And now, after making the tenon, I have to mark the tenon height on my workpiece. Like this I know the length of the mortise I have to cut.
🎯 Read Tenoning on the jigsaw table
Now I use a marking gauge to mark the centre line. I could also measure the width an then mark the centre, but if I use the marking gauge in both sides of my workpiece, I know if I make the mark exactly in the centre.
Then, now I will use the drill press as a mortising machine following the lines I made in the workpiece.
The drill bit diameter is the same as the tenon width. This is because, when I made the tenon, I made sure the tenon width was the same as the diameter of this drill bit.
So now I just have to set the swivelling fence on my drill press table, so the drill bit point is exactly on the centre line I made before using the marking gauge. And I lock the swivelling fence. Like this I can drill in different positions along that line, and overlapping the holes.
I will make a through mortise and tenon joint, but on this drill press I cannot drill this piece as deep as to reach the other edge. It just leaves some marks. So I turn the workpiece and I drill on those marks.
Now I use the drill press as a mortising machine, moving the workpiece from one side to the other, while the drill bit cleans the excess of wood I have left between the holes.
I insert the bit about 1cm in the first hole, and I move the workpiece to one side. I insert the bit another cm and I move the workpiece to the other side. If I insert the bit more than 1cm each time I will force the drill press a lot.
And so on and so forth until I cannot move the drill bit down anymore. Because, as I mentioned before, on this drill press I can’t reach the other side of the mortise. So I have to turn the workpiece to finish the mortise from the other side.
Now I have two options: I can round the corners in the tenon; or I can square the corners in this mortise.
In this case I will use a narrow chisel to cut square corners in this mortise.
So I use a wooden mallet to hit the narrow chisel to cut the corners. Like this I’ll get a mortise with square corners that will fit around the tenon to make a nice wooden joint.
And here we can see the rectangular mortise once I’ve cut all the corners.
Now I can fit the tenon to make a mortise and tenon joint. In this case I get this kind of T joint. And because this is a through mortise and tenon joint, we can see the end of the tenon, so I can see how precise is the joint I made. And I must say it is not perfect, but once I glue it I’m sure it will be a very strong wooden joint.