Mortises for the Desk Stand

This post is really about mortising the desk, but I just wanted to show you how I dressed up the heads of the screws that will be used to fasten the brass mounting brackets. I generally use traditional slotted-head screws on my pieces, however, this time I've chosen the more commonly available phillips head. So, needing to come up with a new method of dressing the heads, I decided to turn each screw, one at a time, in a drill. With sandpaper on a small block of wood, I was able to produce a simple circular brushed finish that complements the phillips head pattern.

Now, it's time to focus on the mortising. Below, you can see the four legs for the desk. It was a real challenge to make decisions on grain orientation, as the plank only yielded a small amount straight grain which I reserved for the horizontal beams and stretchers of the stand.

Each leg has its own character, such as this knot which blew out during a pass through the surface planer. Although there were clues, including traces of bark inclusions around the knot, it looked very solid. The reality of the situation is that this branch was pruned or broken off in the wind and developed localized rot around the wound, which was stabilized after it healed over. Anyway, I think it addes a bit of character consistent with the overall piece. The open knot... stays.

It's been a long wait, but finally all of the wood parts have reached a moisture equilibrium. All of the final machine milling of the stock has been completed and I'm all set for the mortising.

Or am I?

Because of the double and triple mortises in some fairly large parts, I've needed to extend the clamping post on the mortiser X-Y table to provide the height needed to hold the parts down. You'll see what I mean in a minute.

Below is a transparent preview of the desk design showing some of the floating mortise and tenon joinery that I'm using.

Here is a double mortise for the tenons that connect a long side beam to the leg.

And here is the corresponding double mortise in the end of the beam.

You're probably wondering how I supported the beam on the tiny X-Y table. Well here's how I did it!

This shot shows how, after cutting the first mortise, I added the bottom shim, then, after cutting the second mortise, I added the top shim. Using shims consistently in this way makes sure that the spacing of the mortises matches between one part and the next for a perfect fit of the tenons.

These end mills really do a nice job on the mortises.

Not all mortises are created equal, however. The beams and stretchers at the ends of the desks will be curved, so to accommodate the resulting angle in the machined stock, I needed to make a support block at precisely the right angle (2.34°), or as close as I could get it within reason!

Once the sloped block was made, the mortising continued as before. In all, there are a total of 60 mortises in the desk. So, I guess that tomorrow I'll begin cutting and fitting the floating tenons. Later this week I hope to have the entire desk dry fitted for previewing, and ready for shaping the stand parts.

Well, that's it for today. Time to get some rest.

Hej då, and happy shavings!

Craig