Leg and Rail Mortises

Mortises on the Leg are easily done on one of the two the Horizontal Mortising Machines

we will be using a 1/4" end mill bit to cut a 3/8" wide mortise

 A 1/4" piece of MDF is is held to the table with double sided tape.
It is not obligatory to add MDF to the table, but it sure is useful when layout lines are needed.

The center is marked on the MDF before beginning to lay out lines for x axis

Then we laid out the length of our mortise equal on each side of our center line

Because we laid out our 4 legs and test piece, the mortise can be lined up with the lines on the MDF then clamped in place

the y axis can now be set by raising or lowering the table. Because the bit is 1/4" and the mortise is 3/8", you can choose to line up the top of the bit with the top line, or the bottom of the bit with the bottom line.

oops. This blackened layout is incorrect. only the 3/8" haunch  will be cut.

First set the Z axis (the depth of the haunch) at 3/8"

Lock the mortiser|s  depth 

After the bit is lined up with one side of the x axis, set the stop on the opposite side of the table.

Then do the same for the other x axis. (inside the end of the Haunch)

Here is the first cut. Notice the entire width of the mortise is not done yet.

 

Then flip the leg over and place it back on the layout lines.

Clamp it down and cut out the remaining part.

Note the feed direction. In the video above the table jerked because the cutter was fed the same direction as its rotation. this may result in imperfect machining.

Since the mortise was cut twice (once from each edge) it guarantees a centred mortise

Don't fret is the mortise is not exactly 3/8". Remember we have to make the tenon fit the mortise.
Yes I know. The top of the haunch is not completely machined. A bit of chiselling will be required.
don't forget to cut all 4 legs on two sides.

The height of the rest of the mortise is 2 1/4"

Now a new set of layout lines must be drawn on the MDF. 1 1/8" both sides of centre to total 2 1/4"

reset the depth (z axis) to 1 1/6"

Reset the x axis to below the bottom of the haunch.....

......and the bottom of the mortise with the stops

Now repeat the same steps by flipping the leg over and machining each mortise twice.

And there you have it. Verify your mortises are correctly machined according to plan.

Do you see how well this joint is engineered according to the properties of solid wood?

Of course there would be a way to set this up and have the mortiser cut clean through the haunch.

If you have figured it out I'd love to hear from you in the comments.