In the last post on the GTI iPad Mini project, we went into some detail on the head unit disassembly and circuit board work we did to make the iPad work in concert with the OEM radio to provide the ideal user experience. At the end of that step, all that was left to do was to fabricate a trim panel that would allow us to mount the iPad Mini, the original radio's rotary knobs and the newly fabricated switches in the dash of our GTI. This is really the most fun part, and involves a good amount of engineering as well as design. Keeping in mind that we were trying to make this look as much like a factory installed unit as possible, there were definitely some constraints to work within that made this step challenging as well! Let's get to it: The first thing to do was basically to measure out the factory radio opening, the iPad Mini's true screen size precisely to the edge of the bezel, and to position the openings for the rotary knobs. Rather than waste a lot of expensive material in the fine-tuning process, we used our in-house laser cutter to make basic templates out of cardboard until everything was just right. Here we have the basic shape of the panel that we will be making to complete the project. Note the close confines! The rotary knobs almost look like they're not going to work in the desired location, but the posts that the knobs press on to allow (just barely) for this tight tolerance.
Using the laser cutter has allowed us over the past few years to design and fabricate pieces that not only are infinitely more precise than ever before possible, but also pieces that were nearly impossible to make using the tools that we were previously familiar with. For example, you can't cut a square inside corner with a router. It's simply not doable. The closest you can get is a 1/8" radius corner, which can then be filed out to be square. You'll see in the following photos just how small and detailed the pieces that the laser cutter can make are, and the amount of detail we can add to a project using this new tool in our toolbox. The design of the dash panel was done in Adobe Illustrator, which was then exported to the cutter. This doesn't mean that there's not a ton of hand-fabrication involved as well! The laser can only cut in two dimensions, so there was a lot to do after the fact with our typical tools - routers, sandpaper, primer, paint and the like.
Afte a bit more design tweaking, test fitting and test cutting, we made a final cardboard template before moving on to cutting the base trim panel out of 1/4" clear acrylic. The idea with the rings around the new function buttons for FM, AM, MEDIA and HOME was to make the new trim piece fit into the design aesthetic of the car's original radio, where all the control buttons are trimmed with thin silver rings.
We kinda jumped ahead a bit with this next photo...unfortunately we were so excited about how the piece was turning out that we didn't take photos of the piece as it came out of the laser cutter, or of the router steps that followed to add the dimension to the piece that you see here. Essentially, we first used the laser cutter to "engrave" a 1/8" deep channel around the control switch locations so that our silver detail rings would fit into these areas and be flush with the finished surface and buttons. Next, the laser cut the insides of the button holes, the opening for the iPad Mini screen, the rotary knobs and the outer shape. We then went in by hand with a second jig adhered to the first with double-sided tape to cut a 45 degree chamfer all the way to the edge of the opening for the iPad's screen. We also added a 1/4" round over all the way to the edge of the bottom of the panel using the same technique. The factory radio has a similar rounded edge at the bottom that we wanted to keep in the design for an OEM look. Next, the piece was flipped over and 45 degree chamfers were added to the back of the top edges and sides to allow the new trim piece to press into the dashboard. These cuts can be seen in some of the following photos. Lastly, the entire piece was hand-sanded from 80 grit up to 600 grit to smooth out any machining scratches and painted with SEM Color Coat Landau Black spray dye. This is by far the absolute best paint we've found to match the OEM color and texture of most car interior trim.
The 1/8" thin trim rings for the buttons were also cut with the laser, which were sanded in the same fashion and finished with SEM Color Coat Silver spray dye. It's amazing how much like metal this paint makes a simple piece of cut acrylic look. We used this technique for many of the trim pieces in the Chrysler 300M project from a few years back as well.
Here's a nice shot of the dash trim piece before fabricating the buttons and attaching all of the components.
The four function buttons we planned to add turned out the be pretty tricky. We used a piece of 1/4" acrylic as the backing material, and a piece of 1/8" flexible sign material (the same stuff they use to make name tags for fast food restaurants) as the actual button itself. The concept is that the surface material flexes enough in a given area to press on the embedded microswitch we wired up in step 2 of this project. It took a bit of tinkering, test cutting and design changes to make this work as expected, but here's the final design. The inside surface of all four buttons can be pressed to activate the function, while the outside surface is fixed. The small hole cut in the backer material is for the microswitch to mount in securely. The beauty of this design as well is that the engraved text on the button face will light up as the original led is directly behind the clear backer material. All of the OEM radio buttons' text lights up, so we wanted to make sure that the new buttons did as well.
Material was cut for all four buttons, which were then assembled and mounted to the dash trim piece using cyanoacrylate adhesive.
Getting the iPad Mini mounted was pretty straightforward - a few pieces of 3M bodyside molding tape around the perimeter of the trim opening and some felt trim tape, and that part was done. We mounted the iPad in this way to allow it to be removed down the road if we ever decide to use it as a standalone iPad again. No point in ruining it with brackets and screws when this mounting method works so perfectly. Mounting the circuit boards for the rotary knobs, switches and lightning turned out to be a bit more difficult, but was accomplished in the end with 1/4 acrylic standoffs which were then drilled and tapped to accept screws that go through the original circuit boards in their original mounting locations. This was done so that they can also be removed if need be and placed back into the factory radio. Some serious epoxy would have worked here, but screws are always more precise and repeatable! You can also see some small metal tabs at the top of the trim piece in this photo - these are used to hook underneath the AC vent trim to keep the top of the new trim piece sitting flush in the dash. These were fabricated from 1/16 steel plate, which was drilled and tapped so that it could be screwed onto the acrylic trim panel.
To mount the bottom of the new trim piece, we simply attached the factory AC control trim bezel to the iPad Mini trim piece with screws that were again drilled and tapped into the acrylic panel. This allows the entire piece to be plugged into the ribbon cables we left connected to the factory radio and then simply snapped in place using the clips that were installed on the AC control trim by Volkswagen. We wanted to make sure that installing and removing the new piece was as easy as installing and removing the factory radio for future service needs. This is one of those steps that is really important to keeping the functionality of the vehicle intact, and takes some engineering to work out. We could always have glued the piece in place, but that would be a real nightmare if it ever needed to be removed for vehicle service or upgrades down the road.
At this point, we also installed the Apple Lightning to 30-pin converter that allow the iPad Mini to connect to the car's charging and auxiliary input circuits, and added a two-pin connector to the wiring for the Sitachi Bluetooth remote that handles the home button function mentioned in the previous post. We now had a truly plug and play single piece that was easily installed and removed from the vehicle in a matter of minutes. I really like that it all came out completely self contained.
...And there it is! Done. We ended up making a cool custom wallpaper for the lock screen that matches the OEM radio startup screen that is included below - please feel free to download and use however you'd like. In using the iPad Mini for a while in the car now, we definitely recommend a music app called Track 8 that simplifies browsing and touchscreen control in the car environment. The Apple music app is not designed with large enough control surfaces to make it safe for browsing while driving! Track 8 lets you use large swipe commands for most music controls, which is really nice when you don't want to be focusing on the screen at 70 mph.
There's not too much more to say besides we're really pleased that this project turned out pretty much exactly how we intended! This is always a combination of tools, luck, skill, planning and execution, so it's always a happy moment when it's done and actually works as planned. It's really a pleasure to have such an easy interface for browsing through thousands of songs in the car that looks like it came from the factory. We've done a little browsing, a little YouTube, some navigating, etc, but the primary reason for the upgrade was music, and this beats Volkswagen's solution (even with the included on-screen iPod interface) hands-down.
Thanks for checking out the latest project from us at 2point5, and please look out for an exciting new product from us right around the end of the year! We'll keep innovating as long as the need is there...