Large hole cutting method suggestions
About to rough in my plumbing for a new shower. I am using a Grohe valve that uses the Rapido Smartbox (see pic). It requires a 140mm (5 1/2") +/- 1mm (0.040") hole. TIle is 12 X 24 porcelain near 3/8" thick. I don't want to trap myself in a difficult situation with hole location versus tile and grout lines in consideration of cutting the tile. The good looking solutions to me are cross hair the grout lines and cut out quarter circles from the tiles (seems a very risky layout proposition) or full circle inside one tile (seems pretty forgiving layout wise). Since a 5 1/2" diamond hole saw is a $300 tool that is not going to happen, I am looking for advice on layout choice and cutting method. I have seen the slice and nibble but I have a hard time imagining I can hit the +/- 1 mm doing that, and it seems impossible for a closed (or partially closed) hole. Any advice on layout and or cutting is appreciated.
4 inch grinder blade. Score the circle with the grinder. Then make plunge cuts to the score line like a pizza. Knock out the pizza slices. I then use a cone bit on the same grinder to smooth the edges.
Amazon. $40