tech talk
Keep it Secure and Serviceable At this point, we will determine the
location for the products that we are inte- grating. In doing so, we will focus on how these items will be secured to the car. Remember that a vehicle on the road is a hostile environment for us. The product is being subjected to violent bumps and g-forces. And that’s just under normal driving conditions. If the vehicle were to get in an accident, a poorly secured enclo- sure can become a deadly projectile. So, it’s important that we focus on how we are securing our products. Selecting the proper mounting hardware is crucial. At Musicar, we go to great lengths
to attach to factory mounting bolts whenever possible. This does require a considerable amount of time to engi- neer and fabricate brackets. If this time is not allowed for in the budget, using Rivet Nuts (Nutserts) is a viable alter- native. Rivet Nuts attach to sheet metal just like a rivet, and they provide a solid and secure mounting solution. They also allow for repeated removal and reinstalla- tion of the mounting hardware. Another option when mounting to any
metal surface over an eighth-inch thick is using a tap to create a mounting point. What we are trying to avoid here is running a sheet metal screw or, even worse, a dry- wall screw into the sheet metal of the car. These types of screws were designed to be
58 Mobile Electronics May 2014
installed once, not removed and reinstalled, and can cause the sheet metal to strip out. I’m particularly keen on maintaining
serviceability in my projects. If another installer (or any technician) needs to get in after me and service the car or our product, it’s important that they are able to disassemble and reassemble the vehicle without sacrificing my hard work. If I am installing a device to a factory panel, I’ll always install a disconnect on the cable so that the mechanic can simply unplug the part. If the trunk needs to be disas- sembled, I want to know that it can be reassembled with relative ease, and that it can be done multiple times. Drywall screws and MDF are not a wise choice for panels that may need to be ser- viced in the future. If you’ve ever removed and reinstalled a subwoofer in an MDF enclosure, you know that eventually those holes will strip out. Whenever possible, use
hardware that is designed to be removed and reused. This includes machine screws, threaded inserts and Nutserts. We will also need to decide what
materials to use as our substrate while building the foundation. There are several factors that will affect the selection of the materials, but the primary factors are moisture and weight. The most common material in our industry is MDF (medium density fiberboard). We choose this mate- rial because it is cost-efficient, consistent in density and thickness, and relatively easy to machine and sculpt. The down- side to MDF is that it is heavy, it has poor screw-holding capability compared to hard woods, and it is not at all weather resistant. If MDF is subjected to moisture, it swells and loses its integrity. If it is used for a trim panel, this means swollen, dis- torted panels. If it is used for a mounting solution, this means a compromise in
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