MOUNTING the SUBWOOFERS
It would be a shame to go through all of this work creating a nice enclosure, only to mount the subs with inferior hardware. Screws in MDF are adequate at best, so the use of something stronger and more durable is definitely recommended. I chose the popular method of using “tee nuts” to fasten the subs to the rings.
To use the tee nuts, you drill a hole in the MDF, and insert the tee nut in the hole, inside the enclosure on the bottom of the sub ring. Then a corresponding bolt is threaded through the sub mounting hole, through the MDF, and into the tee nut. The tee nut has “teeth” that will bite into the MDF and provide a very secure mounting once the bolt is tightened down.
A note about tee nuts: If you know the orientation of your sub(s) BEFORE mounting the rings to the mold, go ahead and drill the mounting holes and insert the tee nuts at that point. Use a hammer to set the teeth into the MDF by banging the nut into place. Unfortunately, I was unsure of the exact position of my subs before the enclosure was built, so I had to install the tee nuts afterwards. This proved to be a hassle, as the only good way to set the nuts in place is with a hammer – and obviously, a hammer did not fit or swing well inside the finished sub box. It was necessary for me to pre-tighten a bolt into each of the tee nuts to set the teeth into the MDF, and even this did not work as well as hammering them in place. Several of mine fell out later on. If at all possible, hammer them in before mounting your sub rings in the mold.