I finally reach the point at which all the preparation of the joinery leads to careful pre-assembly layout for drawboring the mortise and tenon (M&T) joints on the desk. For example, for the leg stretchers, I drill only one hole using an egg beater drill – the tape marks the depth for other holes, such as on the legs:
I find it important to keep track of which side will eventually be up, and which will be facing the floor:
I always make a spare of everything, including legs. This allows me to test the joinery; in this case I am able to test the offset for drawboring, to ensure truly tight assembly of the joint:
The pre-drilled joint:
And testing for offset of the holes, which will allow pulling together the joint truly tight – - the holes in the tenon are offset from the holes across the mortise by approximately 1/32″, and closer to the shoulder; it is this offset that allows pulling the joint tight:
The pegs I will use to pull together the joints on the legs will be 2-5/8″ long:
The front aprons also will be pulled tightly to the legs by drawboring. In the following photo I am marking the tenons from the already-drilled holes on the leg:
Once the drilling is finished, I turn my attention to sanding, in preparation to applying the finish. To avoid rounding corners unnecessarily, I place the two leg stretchers together on the bench, and sand them in tandem:
The larger pieces, such as the legs, are sanded first with the random orbital sander; then I sand the corners by hand, using one grit higher, and sand lightly to avoid leaving scratches:
In preparation for dark toning the dust cover that will also be the support for the drawers, I apply two coats of a wash coat of dewaxed shellac to the surface that will be under the desk, facing the floor:
I am getting close to being able to do the final assembly, followed by application of the finish.
Finishing tip/preview: Some of you will wonder why I apply the wash layers of dewaxed shellac. I do this to ease the process of applying the finish. I will also be applying a wash coat of dewaxed shellac to all the aprons and the drawer fronts, which are made of white oak. This is crucial, as the shellac will isolate the highly acidic (that is, low-pH) white oak surfaces from the waterborne topcoat I will be using. Why is this necessary? Waterborne coatings are typically high pH, around 10, or even higher; if used directly on high-tannin woods, pin-holing of the topcoat is very likely to result, with ugly results, and ruining of the finish. Using dewaxed shellac isolates the wood surface, paving the way for a beautiful finish using a waterborne alkyd varnish. This makes it much easier to achieve proper leveling of the four topcoat layers I will apply.
Related posts:
Additional reading about the stand-up desk.
— Al Navas
About Al Navas
