Tuesday, May 24, 2022

Enter the Headbanger (Part 2)

The effort to design and build a custom headbanger cabinet took a while. And, there is a ton of detail, so I split this into multiple posts. Ultimately, this took me a few weeks of sporadic, and sometimes dedicated time, to do. At this point, I have the cabinet structure built, the speaker boxes attached and the speaker wire in place. So today, we solve for the mounting, finish the shaping, add trunk carpet and finish the electrical bits.

Plan to Mount
Prior to the assembly I described in Part 1, I rough-looked at a mounting plan. I took the cobbled-together OSB almost-a-cabinet out to the bus to consider how I could attach it. The cabinet was mostly stable, but I felt that adding the speaker boxes and other bits would help me plan for the mounting brackets. I couldn't be sure what I could reach or could not reach without actually having the speakers in, the shelf in, etc. With a considerably heavier cabinet, I headed out to the rear end of the bus. When I held a single speaker box in place, I used a rubber strap to hold it against the torsion spring for the rear hatch. That would not work this time. Instead, I stacked cushions and whatever I could lay hands on underneath it to wedge the cabinet up against the ceiling. It looked ridiculous and I regret not having taken a picture of the wobbly stand it was on, but I could think about where to place the brackets without a balancing act or having the cabinet shift side to side or front to back as I considered different angles.

I discovered that my initial measurements were slightly off for the inner supports, and I had to remove about 1/2" of the front-most 3 inches (front to back) off the top of the top-most edge of the 2 inner supports to snug-in against the ceiling. In the picture on the right, you can make out a small cut-away just above the chairback in the background. After some quick adjustments with a hand saw, I could return the head banger to the bus for fitment.
filling in gaps with cardboard
The cabinet is not terribly heavy, and even with the speakers installed, I don't think it will be more than, say, 20 pounds. While it is not a big deal overall-weight-wise, it is very front-heavy, and I think that will matter. Figure, the speaker boxes and the speakers are most of the weight and that weight is all front-of-center. So, the rear mounts will provide stability, but the front mounts will be carrying the weight. This is especially obvious in the picture on the right, here, where I have a roll of tape wedged under the passenger-side speaker box so it will sit flat on a table. I decided that I would put a bracket on all 4 supports up front. On the outer supports, the bracket will point out and on the inner supports, the bracket will point in. Any other orientation would have been unreachable because of the speaker-boxes. Either in the interest of consistency or overkill, I decided I would put 4 on the rear as well, but with the installs reversed: outer brackets facing inward and inner brackets facing outward. This was necessary to account for the added shelf running all the way back to the rear edge of the inner supports, effectively blocking my access to a mount point above in the rear.
I marked on the ceiling and on the cabinet where the brackets should go, and then took the cabinet back into the garage where I installed 1" angle brackets with wood screws. I returned to the bus with the brackets mounted and re-checked the spots in the ceiling where the holes needed to be bored in, marking them clearly with a sharpie. Continuing my avoidance of sheet metal screws, I bored the holes out for and then installed M4 riv-nuts. I confirmed the will-be-cabinet mounts aligned with the riv-nuts and then removed it so I could complete the cabinet. 

One More Thing
cardboard rear-support
While I was working on the ceiling, I prepared the install of the rear dome light between the 2 speakers. I had run the power leads earlier, and I was already there, with a drill. I laid down on my back, and considered where we would be lying down reading a book. Based on where a book would naturally rest in my lap, with my head propped up on a pillow, I figured where the light position should be, and marked it on the ceiling. I measured off of that to set the holes for the fixture, with the switches facing forward. I bored the holes and set 2 more M3 riv-nuts in place so the light fixture will mount with bolts, not screws. Again, that riv-nut tool kit is becoming one of my favorite new acquisitions.

Fill-in The Front
Once I had positioned and installed the speaker boxes, there remained a large gap between the top edge of the speaker box and the leading edge of the headbanger. I filled in this space with carefully cut firm cardboard that I then carpenter-glued into place. These stretches of cardboard will only serve as a backing for the headliner, but they are firm enough to hold in place. Since they are far out of the way, I think that once the cabinet is installed, the headliner and the underlying cardboard will go untouched for years. This pictures along the right side show the fill-in efforts, and how I created some support-from-behind with additional cardboard bits. I taped the seams as well, so the headliner lays down smoothly. After the glue set-up, I tested the relative strength of the cardboard bits by pressing on them with my fingers. They held firm enough that I figured they will hold up.

Final Assembly: Trunk Carpet
USB panel and ports
I was approaching the home-stretch, or at least it felt that way. It was final assembly time, and that includes final surfaces. I chose to use 2 different fabrics. For the areas where hands will touch regularly, like on the face where the USB chargers are and the shelf, I am using trunk carpet. I figure it will show a dirty finger less than headliner material would, and it is designed to withstand some friction. For all of the other surfaces (outer-facing sides, over the speaker boxes, the very bottom) will get headliner. They both apply with stinky DAP contact cement (or spray adhesive). I brushed both the trunk carpet and the target underlayment, wait a few seconds for the DAP to get tacky and set it. You only get one shot, so measure and plan carefully. I chose to use many small pieces, in contrast to the single complicated piece I used on Oliver's sub-box. To create some time to fiddle the pieces around, I used carpenters glue on the larger faces of the trunk carpet. It does not set up as fast, so you can wiggle the carpet into the exact right spot. Then, I did the outer 1/2" edges with the contact cement.
fun with wiring
Before carpeting the USB face, I installed the face to the cabinet with a staple gun and tapped the staples home with a framing hammer. To make sure everything stayed put, I edged the panel with carpenters glue. Once well-fixed, some trunk carpet went on. I cut out the holes for the USB chargers and the speaker switch with a razor blade and then installed them too. Before I repeated the install process with the shelf, I applied trunk carpet behind the USB face on the floor around the rear edge to finish the look. I also applied trunk carpet to the floor area behind the speaker boxes, around the inner supports and on the rear-facing side of the outer supports. I did not address the rear of the USB panel, so in that large black sea, there is this large white rectangle. Yuk. I'm not sure if there will be an easy way to get in there and "black" it. My goal was anywhere that could be seen or touched inside the bottom-most shelf from the rear hatch got trunk carpet. The result would be a view from the rear will be completely blacked out, and any use of the rear-facing shelf has dirty-finger protecting trunk carpet. That center section is virtually unusable from the rear so I may make a block-off insert to keep the look clean, and the wires from getting disturbed. The plate will wait. 

Final Assembly: Wiring
At this point, I wanted to finish the wire routing, so the rear-facing area was as tidy as I could manage. I ran the power and ground wires for the USB chargers out through the hole I had bored for the left (front is front) speaker wires, and routed them up the outside of that inner support, setting them immobile with staples. The speaker wires got covered in that black plastic wire wrap so they will not get caught on anything that is set on the rear-facing shelves and, because of all the black carpet, they will visually disappear. I verified that I had enough USB supply-side wire to reach the mid-point above the center shelf, added female wire connectors to them and then popped a chair-connector onto those connectors. 

Out at the bus, I added a male wire connector to the orange wire, completing the set up for the headbanger wiring. I also made sure that the speaker signal supply cables were long enough to drape over the right speaker, where the wires in the bus are. In the picture on the right, you can see just how much extra speaker wire I have hanging down from the bus ceiling. Why? So I can connect things before mounting the headbanger and then tuck the extra up above. Also, by having such long speaker wire leads heading to the stereo, I could unplug the headbanger and plug in a pair of float-remote speakers. Will I? Probably not, but I saw little harm in creating the option.

I was almost ready for the shelf. This was complicated a little bit by the OSB supports I had made. I wanted them to visually disappear, so I spent some time cutting and shaping small bits of trunk carpet to cover them. Finally, the shelf went in, as evidenced by the pictures above. Unlike the glue-on and staple fun of the USB charger face mounting, I wrapped the shelf with carpet and pushed it into place from the front. It is effectively held in place by friction.

The keen eye will notice that the trunk carpet needed some perfecting and trimming. I will address that before I get after the headliner install... which will wait until next time / later. I am feeling the time pressure, and feel the need to get this buttoned up soon. Phil and Friends is coming up fast and we don't have any interior lights or a stereo. So, this is where I am leaving the headbanger for now.... sitting on the rear of my US General rolling tool cabinet. I will get back to this, just not for a little while, probably. LOL's.

That's it for today. Thanks, as always, for following along-

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