router cutter choice

[oceanobsession]

What would be the best size router cutter to use for cutting out large holes for speakers, ive tried small bits but they can break off but you get less dust, ive used the kitchen worktop 12.7 cutter for the last lot, but loads of dust, I have to go 42mm deep. cheers phil.

 

[Steve Maskery]

I'd rout out to about 6mm deep with a 1/2" cutter, then saw out with a jigsaw, then trim up with a flush-cutting bit.
42mm is a long way to cut through, even in stages, with a 1/4" bit.
S

 

[MMUK]

I think the general rule of thumb for depth is half the diameter in one pass so it would be a max of 1/4" depth with a 1/2" cutter per pass

 

[foxhunter]

+1 for Steve's solution