I'm building a vanity for a master bathroom using a solid surface (SS) countertop with an undermount sink. The countertop is just shy of 1/2" thick, about 12 mm. I've been studying the internet for information about how to cut the hole in the SS. There seems to be two schools of thought. In both cases a template is used with a router. The first method uses a plunge router and recommends a minimum of 2 passes, cutting about 1/4" deep per pass. The type of router bit is not stated. The second method has a hole drilled in the center of the cut out with a hole saw. Then a straight router bit with bearing is inserted into this hole and cuts of the entire sink cutout in a single pass. That is, the full countertop thickness is cut with a single pass. In both methods a sacrificial piece of plywood is underneath the countertop during the cut to support the cutout during the entire cut.
I'd appreciate any information and recommendations on these two methods or if there are any other methods the membership would recommend for this process. In particular, please provide detailed information of the type of router bits recommended, including whether the template is on the top or the bottom of the countertop and if the router bit has a top or bottom mounted bearing.