Per your request, Sandy, I am posting how we did the modification for an apron front sink. Bear in mind, these are IKEA cabinets that are very "hacker" friendly. The base cabinet is 30" and the sink is just shy of 30"; it's almost 20" from front to back and 10" deep. I didn't take photos of the entire process, but I did take a few. Hopefully, they will better illustrate my attempt at explaining how we did this. First we turned the sink over and measured the sink, itself, (three times for accuracy.) and using a straight edge, drew the outline on the base cabinet sides, with the cutout to the front of the cabinets. We basically notched out the sides of the cabinets where the sink would sink, keeping in mind that the top of the sink had to be flush with the top of the cabinet sides. Since we want our sink to sit somewhat proud of the cabinet, we made our cut to be 19" deep by 10 1/8" high. Hubby used the table saw to make the cuts. I assembled the cabinets, as I normally would, just without the front brace, as that is where the sink sits. We carefully turned the cabinet over the top of sink to make sure that the top of the cab sides would sit flush with top edges of the sink. We then placed the rails over the sink bottom, so we could make certain the disposer would fit within these rails, and that the rails would properly cradle the weight of the sink. We did this by actually turning the disposer upside down and placing it over the sink hole. We then ripped 1" from the 2X4s. We clamped the rails on the sides of the cabinet and measured then cut our cross braces. We removed the cabinet from the sink before DH pre-drilled holes on the sides and then screwed the rails into the cabinet sides. We turned the cabinet upright and placed the sink on the supports to see the fit. This is one picture I forgot to snap. :^/. Sorry. Here is a top view of our sink supports: . We again removed the sink, and I finished the cabinet by nailing the back onto it. I will take another photo later so you can see the sink sitting on it. DH is at work, and it is just too heavy for me alone to get it on there. I hope that helped a little.

Unlike you, an apron front sink was my one "must have". The reason I settled on a Rohl was that I just liked the look better than any of the others. To me, it looks more original. There are irregularities and that is why they say not to cut your sink base until you have your Rohl in-hand. In hindsight, I should've sent my Rohl back and gotten another due to the variances in my sink. However, my contractor didn't tell me it was so out of wack until the granite was installed and I noticed the space between the counter and the top edge. In my mind, it was too late by then. My contractor, who is really a skilled craftsman, said cutting the space and putting in supports under the sink was the hardest bit of construction he's ever done. And that says ALOT. FWIW, I think he did a superb job and definitely better than some I've seen. If you get a fireclay sink, make sure your contractor is aware of it and your cabinet guy is aware of it and that they are all onboard. They are definitely unique products to install. Still, with the gap and everything, I wouldn't change it. I really like the look. As for the function, I couldn't say. We're still a week or so away from being in the kitchen. Good luck.

"For the undermount sink we screwed two strips of wood to the side walls of the cabinet to support the sink." I strongly discourage this procedure. I constantly repair leaking double bowl stainless steel sinks that have been supported this way. Most sinks do not have a stanchion between the bowls. This means that each bowl is supported by wood on one side and steel-on-the-flat on the other. Steel-on-the-flat flexes, especially with the weight of a disposal pulling the sink down, causing leaks. Leaks cause rot, rust, insect infestation, and unsanitary gunk where you're preparing food for your family. Of course I have tons of pictures to support my claims. Wood cleats cannot provide the constant upward even pressure on sinks that a Hercules Universal Sink Harness (Braxton Bragg) or a Sink Strap (Regent Stone Products) can. You can stand in a strapped sink. You can jump up and down in a strapped sink. You can push on the steel-on-the-flat and it will not budge; it can't defy the laws of physics. And straps take up less room than cleats.

I too want to give a shout out to Kimmy for her detailed instructions. I just installed a whitehaven following them. I will add this the curve for the cutout is 4" so a 4" hole saw on your drill will give you the perfect cut then you can use your circular saw up to the holes on the sides and bottom. I don't own a jig saw so I used the same hole saw that I got to cut my butcher block with a reveal (also 4" obviously). In addition to Kimmy I want to thank Joseph for recommending Pete's sink mount. I realize most on this thread have already installed using Kohler's instructions but Pete's sink mount makes getting everything in and level super easy and you can adjust up or down with the sink in place unlike Kohler's 2x4 method. This is an FYI for anybody that comes upon this thread later. Steve - Ikea sells a kit to attach a door to a drawer that has a template to drill the holes. I realize you don't need the hardware but it might be worth it for the template. https://www.ikea.com/us/en/catalog/products/00280755/