Best Way To Cut Out A Rectangular Vent (Port) ?

[tlarwa]

From a 3/4" x 11.25" (12" nominal) solid red oak baffle? The vent will be 2.34" x 9.75" in size. I have at my disposal a router, a Dremel "Advantage" rotary tool and a jig saw (which I've never had good luck with when trying to cut a straight line). How do I assure a straight, square rectangle, with (hopefully) square corners?

Thanks!

Tom

 

[Richidoo]

Make a pattern for the router to follow, that is the exact size you want the hole and clamp it to the part to be cut. Make a pattern that is deeper than the length of the bit from bottom of the bit to the top of the bearing so the bearing can follow the pattern even on first shallow cut. 3/4" plywood sideways on edge should work for this, the router base can ride the top edge of the pattern safely. Use a "Pattern Flush Trim" router bit, with the bearing above the cutting blade. Something like this... These are usually 1/2" diameter cutters so it will leave rounded corners, but a file, sanding block or careful chisel work can clean those up if desired.

The pattern edges would need to be smooth and flat, hopefully you also have a tablesaw? If not use a straightedge to guide your jigsaw to make smooth straight cuts. You can tack glue the pattern to the work part with tiny bit of wood glue in 2 diagonal corners. It should knock off cleanly, a little water soak will remove the residue from the work. If the speaker is not assembled yet, tack the pattern to the interior side of the part.

 

[tlarwa]

Excellent. Should I cut the majority of the vent out with a jigsaw first, and then use the flush trim bit to open it up to its final size? Or will the flush trim bit also act as a cutter if I make shallow cuts?

 

[bill_a]

Yes, use the jig saw to get most of it. I like to leave less than 1/4" for the router.
Bill