But what about attaching those to the thin walls of the cabinet?
@tailgunner: Cabinets are ½” plywood box construction. All the 1x3 poplar was pinned to the cabinet sides with 1.25” brads from a pneumatic nailer. All the force on this is compression from the weight of the frame (negligible) and sink. The weight comes from the disposable unit on the sink, plus any water if you fill the sink. There’s no lateral forces.
The sink manufacturer, Ruvati (super quality sinks, BTW, at superb prices) describes a similar frame and support system but made of conventional 2x4s. That would have taken up too much room in a very crowded under-sink situation. In fact if I did something out of 2x4 I don’t think there would have been room for the disposal or my RO system. I believe I measured for all of that and chose a more elegant solution out of hardwood. It worked fine. That sink is very deep. Another thing you cannot see is I put a dense foam cushion on the top of the frame (1/16” thick self stick foam sheet from a craft store!) so the sink wasn’t directly on the wood.
Backer blocks on the outside of the cabinet were not really practical nor necessary. Cabinet was already installed. Granite installed. Access to the outside sides not practical.
Granite installation company specifically stated “we just install the granite” and set the sink. Any plumbing attachment or framing must be done prior to granite installation. No way they would have done this.
BTW my Ruvati was (sold the home in April) every bit as nice and as well made as the aforementioned Kohler K5540. (Mine was an apron front model, however) The Kohler costs, retail, $1,000. A nearly identical Ruvati, with all those accessories such as cutting board, colander, drying mat and grid, about $380. Ruvati is high quality
16 gauge SS; Kohler is
thinner 18 gauge. Both Kohler and Ruvati have good quality sound deadening. I believe both are made in China. I actually paid a whole lot less than that pre-Chinese import dancing that the current administration started. It's still a deal. I could not have been more pleased with the Ruvati...I was so happy with the quality that I replaced the crappy builder grade plastic (Ugh!) laundry room sink with a Ruvati SS model.