I hope everyone had a nice weekend. In absence of being able to attach the front baffles to the four custom sub boxes, I made some progress this weekend by filling all the screw / nail holes and sanding smooth most of the 8 subwoofer boxes. I created a little bit of a hot mess when I used a belt sander to take off the lip on one of the 24" sub boxes, creating some sanding gouges which will have to be flattened, filled and sanded to correct. No big deal, just an extra step. Pics of this later this week.
In the meantime I thought I'd try to catch up this thread with the BHS-24 box build before the pics got too old. These pics are from over a week ago.
Since these front baffles were 3" thick, the plan called for additional fixation with screws coming from the back side of the inner baffle layer. Because CNC'ing these screw holes would have taken a bit change and another hour or so of machine time, we skipped this step in favor of me going back and manually adding in the screws. Using a blown up picture of the CAD file as reference, I laid out all the screw locations.
I also laid out the intended handle locations.
I pre-installed all the screws so I could fly through the attachment process once the glue was applied to the other side.
To make sure the handle locations were accurate through both baffle pieces, I temporarily clamped the baffles together and drilled a pilot hole all the way through both baffle pieces.
To install the threaded inserts used for the handles, I had a 9mm bit for the threaded insert, 1/4" bit for the hex bolt diameter, a hex driver and a 9/16" paddle bit to create a slight lip for the threaded insert. Gorilla Super Glue was used in the hole and along the threads of the insert as extra insurance to permanently lock it into position.
Here was my process. First, I used a 9/16" paddle bit to create a slight recess for the lip of the insert so the baffle pieces would lay flat when glued together.
Here you can see this slight recess in action (with the insert turned upside down)
Not pictured, but I then drilled down the depth of the insert with my 9mm bit and then all the way through the baffle using the 1/4" drill bit. CA glue was applied to the inside of the hole with an artist's brush and again over the threads of the insert. Here's the final result, just before installing the inserts.
The 2" Hex bolts would extend into the inner baffle layer, even with the thickness of the metal handle and washers. I used the 1/4" drill bit to drill down approximately 1/2" to accommodate the other end of the bolt passing through the threaded insert.
I installed all the threaded inserts for the handles and the subwoofer driver and was finally ready to apply the glue.
I applied a generous amount of glue to one side of one baffle layer, anticipating the glue to 'soak in' to its adjoining layer. In other words, I applied enough glue for both layers on this one glue-up and let it soak in for a few minutes before binding together.
No pics of the actual alignment, clamping, glue squeeze out, etc. because you really had to hustle to get everything locked down during the working time, but I noticed during the clamp-up I was getting big puddles of glue on my work table. I'm not sure why I didn't think of it, but some of the squeeze out was coming through the threaded inserts for the handles.
Petrified the holes were going to fill with hardened glue and be unusable, I immediately lifted this huge, clamped mass onto its side and cleaned out the holes the best I could and immediately ran the hex bolts into position. I kept turning these bolts every 5-10 minutes for the next four hours so they wouldn't get glued in one location.
Here you can see the handle bolts installed.
And the really nice squeeze-out I was able to get, especially around the future driver mounting location.
I returned the front baffle to flat with all the clamps and added some weight in the middle.
Rinse and repeat for the second front baffle. Mapped out all the screw fixation and handle locations and installed the threaded inserts...
Generous amount of glue applied...
Here you can see the full thickness of these front baffles when bound together
Finished front baffles
With the baffles complete, I turned my attention to coating every single inside corner in both boxes with a heavy layer of PL Premium to further bind everything together.
So that was it for the two front baffles. I'd like to get to the point of permanently attaching them to the boxes sometime next weekend once all the clamps I am able to borrow are back in-hand.