The devil is in the details:
No woodworking job has hard and fast rules but there are always essentials:
1. Planning-These can be sketches, working drawings, Sketchup renderings, miniatures or full scale mock-ups. Krenov said, “Decide what you want to build and why.” Steven Covey says..”Begin with the end in mind.” It may be a sketch but work it out visually before beginning. That is the best advice for any woodworker. I prefer working drawings I get from various sources such a Fine Woodworking. My immediate challenge is to adapt old drawings with mortise and tenon joinery to the Domino system but before I start, I have the changes in hand and in the case of a recent table my cut list eliminated the tenon lengths.
2. Wood and product selection-Krenov reminds, “You have to judge each piece of wood individually and keep your eyes and your mind open to the possibilities.” It is not just pine or maple; it is grain, color, moisture content, subject to seasonal movement. Parts are important. Having the hinge selected, the screw sizes, and hardware leads to successful job selection.
3. Process selection- The Domino is not a tool, it is an idea. Therefore, before setting out, it is important to understand just what is going on with the Domino. The absolute base concept of the Domino is that everything relies on a center point. Therefore, at every step, the matching up of floating tenons (Dominos) depends of references the center point of each mortise with a common edge. Peter Parfitt constantly reminds, “You have to have a scheme.” That is why in advance, layout of the aprons, left, right and top, bottom is critical to the Domino process. I mark all parts in chalk. In a table leg/apron system, it is usually best to work off the top, outside edge. The point is that every cut must work off a common edge and the center point is the main focus of the process.
4. Pre-test- My Dad used to mutter, “I cut this off twice, and it is still too short.” My dad, though, made practice runs. We had to keep cardboard around to scribe boat floor boards and would check the fit of cardboard cut-outs before cutting. Trying out something in advance is why we keep scrap wood around. There is a learning curve to the Domino. “Don’t be in a hurry.” Krenov is reported as telling his students. There is a trick to firmly seating the Domino as well as properly viewing the center line. Best work out these issues in advance.
5. Check List: In any process, there are steps. The Domino is a process with basic variables. In the beginning, it might seem elementary but airline pilots don’t fly planes without their checklist books on their lap. In the beginning, have a cheat card with the list of setting, cutter size, depth of cut, height and width. On off-set depths there might be two settings. On legs and aprons a reveal is possible by adjusting the height. Add to it reminds like registering off the top edge or outside edge. Who know, the dog may bark to go out and you become distracted, a check-list, at least in the beginning work out both the steps and the critical variable of using the Domino.
6. Critical issues- To understand the Domino, it is important to understand the relationship of the shoe and the work piece. It is essential to have a template the exact width of the shoe to hold up to work pieces to check the location of the center point. The height of the cutter center is 10mm from the shoe. This is 3/8 inch. This dimension helps work out the placement of plunge cuts. Plunge cuts require extreme caution. CAUTION: THE DIRECTION ON THE “ON” SWITCH IS IN THE DIRECTION OF THE PLUNGE. If new, and attempting a plunge cut, you may not be fully ready for the plunge and start the plunge by turning on the Domino. Plunge cuts need practice more than any other operation of the Domino. The Domino is badly designed for plunge cuts. The lever and the angle nut interfere with seating the router on a registration edge. The tiny nut of the angle guide is 1 inch from the edge so if you want to use a registration edge, you have about a 1 inch length in which to work.
7. Measuring techniques- As a kid, I worked in a boat yard. I could not understand why boat builders never used measuring tapes. I watched many walk over with a small stick in hand with a pencil mark and set the width of the band saw or table saw. Planes flew in boat building. Wood was made to fit curved spaces by eye not by measure. I think my experience in the boat yard is why the Parfitt spacer system works for me. Measure, when you only have to.
On your issue, I would check which edge on which you are registering the cut. If your cut system has integrity, there is no reason to cut a wider mortise. Set up a system which relies on the narrowest setting.
