Shower hole cutting...
RUGGED said:
A normal Lenox hole saw. The more teeth the hole saw has the better. A fast turning drill is a must.
I use a Milwaukee hole-hawg for all my drilling...setting it on low to drill tubs.
Keep it straight so it doesn't bind!
Just a suggestion...if you haven't used a hole saw before(3 1/2 is a good size!)I would put tape over and around the area you are going to cut. Couple of inches bigger should do it.(remove tape after cutting hole.)Find the center of the hole and drill a pilot hole the same size as the bit in the hole saw.(they come with a centerbit to guide you). Guide the centerbit into the hole you drilled and then proceed to drill the hole. This will keep the hole saw from "walking" on you(moving down on the shower wall chewing up the gelcoat!)Follow rugged's advice about drilling slow and keeping it straight. Just before you get all the way thru is when the hole saw will try to bind on you so keep that in mind.
The shower wall is not that thick so if you force it or try to go too fast the hole saw can start to bounce around and possibly damage the shower.
BTW, a metal cutting hole saw is what Rugged was describing with "many small teeth" as opposed to a wood hole saw with "less big teeth."
As always, use gloves, eye protection, etc...