Install a farmhouse sink by making slight modifications to a conventional cabinet. Farmhouse sinks have standard widths that fit most cabinets. Install the sink before adding the cabinet top.
Begin by installing 2-inch by 4-inch supports on each cabinet side. The tops of the supports should be even with the level lines. Apply a construction adhesive, and clamp the supports securely in place before driving square-drive deck screws through the cabinet sides into every support.
Add 1/8 inch to the height of the sink front when marking the base cabinet front cutout to allow the sink to rest just above the cut edge without the edge supporting it. It may be necessary to remove cabinet doors and replace them later with smaller ones. Cut out the sink front using a jig saw.
Try to fit the sink in the opening by holding the sink from the front and back to make sure that the side supports carry the entire weight of the sink. Check to ensure that the sink is level from front to back and side to side. If necessary, add tapered wood shims to adjust.
Install the sink, and flush the back of the apron tight against the front of the cabinet. Use silicone caulk to fill in the gaps below the sink front and between the sink and countertop.