Bones wrote:
Just purchased a new cooktop. Its 1/2 " too big. Can I use a jig saw
to enlarge the opening?

Yes ... but you need to use a very fine blade and cut slowly . Cover the top
with masking tape where the saw will rub . A better choice is a router with
a collar and guide fixture . The enemy here is localized heat , it can cause
uneven stresses and crack your top .

--
Snag