Good idea, but I'd suggest something like newspaper underneath. Concrete can be textured which leads to cutting issues.Place your drum head on a hard surface...concrete is great like a garage floor or basement floor. Put the center of the Circle Cutter where you want the center of the hole. Press down the stopper and turn the blade. It will cut through the mylar like a hot knife through butter. Voila! Bass drum port!
Thanks for the reference, but that's not what I'm talking about. When it comes to drum ports, KickPorts, and other porting methods, we are literally flying blind as to the exact port size (and depth, if appropriate) that will result in maximum output at the desired frequencies. There are so many variables involved in actually tuning a bass drum via a port (drum diameter, depth, head(s) resonant frequencies, shell resonant frequencies, port placement) that this might be an unsolvable problem without a very complicated, all-inclusive formula.
Dude! Don't over complicate things. Keep the hole small, but big enough for a mic (4 inches is fine) and as far from center as feasible. Simple.we are literally flying blind as to the exact port size (and depth, if appropriate) that will result in maximum output at the desired frequencies.