Thread: Scion xB '06, in-dash Atom 330, Lilliput 889GL; details, pictures, links. Index: pg 1

Designing the Screen Cover

While I had the revised and partly-revised dash parts in place, I cut a cardboard panel the same size as the screen to use as a mockup of the screen cover that I wrote about (starting in post#173). Sure enough, it looks like a flip-down cover will work well, and without a lot of complexity. Here's a view of the screen as it will be placed:



I'll change the bezel so it comes out further from the dash. The top of it will be where the top of the screen is, and it will curve smoothly down from there. The cover will hinge at the top of the bezel. It will rotate open and lay on the flat part of the dash. When closed, it will cover the area from the top of the screen to the controls below it. By concealing the screen, I hope to make the dash look less interesting to thieves.

Even though the screen will be vertical, the cover won't be; it can simply swing down and match the angle of the dash, and flow with the shape of the bezel.

I'm planning to fabricate the cover from polyethylene, like the rest of the bezel, and I've already bought both 1/8" and 1/16" black polyethylene sheet material for the carPC project. I'll need a hinge system that rotates about 270 degrees; I can use a simple black continuous hinge like this (one source for this product is here):



. . . or possibly a plastic piano hinge like this (one source for this product is here):



Either way, I should be able to build it in so the hinge is nearly unnoticeable.

The next part of this is to devise an image to adhere to the cover panel. This image should disguise what's underneath. Time to switch hats and become a graphic artist.

Screen Cover Image

Trompe-l'oeil is two-dimensional work that gives the impression of three dimensions. Here's a non-automotive example I like; in this picture of a building in Lyon, France, the painter is painted onto the side of the building:

Click images to enlarge.

I decided it would be fun to see how well I can trick the eye with this screen cover panel.

I laid out some false gauges, using CorelDraw X3 and gauge images grabbed from Marshall Instruments. I was going to use a clock, but I figured a clock would probably have to actually operate, and this is just a fake panel. I used gauges I'd really want to have in my car.

I reduced the gauge images to the same size as the three climate control knobs that will be below them, about 2" diameter. The bottom gauges align with the three control knobs, so I'm hoping they'll look like an OEM installation. Here's a mockup of the resulting screen cover image:



This mockup is interesting, but it's probably a little over the top. I'll modify it to make it a little more subtle. That's next.

thats damn good. they look like they are on my screen lol.

Originally Posted by pepsibobby

thats damn good. they look like they are on my screen lol.

Thanks. I'd like to take credit for the great work, but the images from Marshall Instruments get most of the credit. I imported them into Corel X3, resized them, and put them in the right positions. Then I built a black mask over them to cover their backgrounds. The mask is the size of my screen cover, and has holes cut out of it to show the gauges.

Screen Cover Image, Version 2

It's been a while since I had a car that had real gauges instead of idiot lights, and I realized that maybe five gauges doesn't look very much like a stock dash. If I have all those gauges, wouldn't it appear that I'd added engine modifications -- stuff the bad guys would want to steal? Oops -- that isn't the impression I'm trying to convey. The whole reason for this screen cover is to make it look uninteresting to the smash-and-grab jerks.

After thinking about that, I decided maybe I'd be wiser to go back into Corel X3 and make a panel with only three of the original gauges plus a radio. The radio image was originally from Kenwood, but I modified it a bunch with IrfanView 3.99 to subtract features. Then I added an AM-FM dial from another radio to make it look like there isn't even a CD player in it. I want it to look like a cheap, no-name radio:

Click image to enlarge.

It might be slick to just screw on a couple of relatively flat knobs and see if that completes the illusion of a radio.

I'll have to admit that these gauges from Marshall Instruments look so nice that I'd like to have the real things in my car. Maybe they're too nice, and I need to find cheaper-looking ones. Hmmmm . . .

Getting Crazier with the Screen Cover Panel

Once I got the panel artwork to this point:

Click image to enlarge.

. . . then I started thinking wacky stuff: what if I actually made these parts 3-D?

I could cut holes in the cover panel material and put the printed image of the gauges behind it; I could put another thin layer of polyethylene underneath to supported the image, and put clear film over the gauge images to protect them. The radio image could stay on top.

. . . or I could add bezel rings on the images of the gauges. The rings could be 1/8" lengths of 2" plastic pipe, sanded smooth, painted silver, and fastened to the cover.

. . . or I could build a box onto the face to mount the radio image on, so it looks like the radio protrudes.

Then I went really crazy: I wondered if I could skip the radio image and use an actual junkyard faceplate screwed onto the panel. So I went cruising on MP3Car to see what others had done. I ran into this masterpiece from f1vlad. It does a great job of concealment. That led me to one of his threads on MP3Car, where some others show similar approaches. And there's another thread on this topic here. The 3-D idea seemed pretty neat.

But, even if I add 3-D parts, I want to keep the fake face light, since this cover will be opened and closed each time I use the vehicle. The heavier it is, the more likely it will take damage just from being banged around. One option might be to find the scrap radio face that I want, and then use it to mold a similar piece in black Alumilite. That would result in a much lighter device because I could remove most of the weight during the molding process, or remove it after molding with a rotary tool, and mount the resulting lightweight shell on the cover.

Whoa, boy. Let's pull back a little on this.

All those 3-D additions would add development time, add work, add weight and add complexity -- for a cover panel that doesn't do anything except fool the bad guys. I have to remember that this panel is theater, not function. None of this effort will make the carPC work better or faster.

So, before going off the deep end, I'll try just the plain panel with the image and a couple of knobs. If it doesn't work the way I want, then I can add some actual 3-D pieces. Lots of options are available. I still hope just the plain, flat-faced panel with knobs will do the trick. We'll see.

Mounting the Screen Cover

I need to take mounting into account as I design this cover panel. I'd prefer that the hinge on top be concealed in both open and closed positions, and that will likely require some interesting engineering, and possibly some fancy plastic welding.

I suspect the traditional approach would be to use the piano hinge (shown on the left), but I think I'd like to try the continuous hinge (on the right).



Click images to enlarge.

My engineer brain wonders how many duty cycles the continuous hinge can stand, especially since it will be right in the sun, so I ran a quick mental calculation. Let's see, even if I open and close that panel four times a day, that's less than 1,500 cycles a year, on a product that has 100,000 cycle (or more) lifetime. No sweat -- it'll outlive the car. It'll outlive me.

If I decide to use the continuous hinge, I'll have to find a vendor who will sell a 12" length of it somewhere. The source whose product is pictured, Monroe Engineering sells it in 50-foot rolls, and has a $50 minimum. I went looking on eBay for "plastic hinge", and didn't find anything that worked. There was a 7-foot length of plastic piano hinge, but it was $30 with shipping.

Other ideas popped up, though. Most of the plastic hinges were on laptop covers, and using a hinge from a defunct laptop is definitely a possibility. Then there was a guy advertising a 1973 Camaro glove box cover with an intact plastic hinge (for almost $60). That makes me wonder if a trip to the auto graveyard might not be an interesting source for a hinge. Hmmmm . . .

As a fallback, I have a length of stainless steel piano hinge already, and that would work fine except for color; it's shiny steel, and I want black.

The extreme fallback position would be to eliminate the hinge and make it a removable cover like f1vlad did here (link is in my previous post):

Accommodating Changes in the Screen Cover

Since the bezel isn't built yet, I don't know what the final dimensions of the screen cover will be. In fact, I'm not even sure about its shape. I'm sure there will be changes in the design, so I'm making notes as ideas come up. I want to avoid having to produce makeshift stuff to solve problems I should have thought of earlier.

Curved Face
I may have to make the screen cover bow a little to match the bezel. The right side of the bezel is shown here (top is on the right), and you can see the curvature in it:



I'll have to match that curvature. I think the bending can be in just the horizontal axis; if I make it a 3-D bend, I suspect it will be tough to get the image to adhere to it without wrinkles.

The bending will probably entail making a shape in wood or metal, heating the 1/8" polyethylene cover material in the (kitchen) oven 'til it's flexible, and then holding it against the shape until it cools. If that won't work, I'll have to produce a metal skin I can put in the oven and lay the polyethylene on until it softens and conforms to the shape.

A third option would be to take it back to the place I bought the material, and pay them to bend it for me, but that isn't very do-it-yourself, and I'd like to learn how to do this. I'll hold off on doing any bend testing until I see if it will be required.

Size Changes
The final size of the image will probably change, because it will match the size of the screen cover, and that will depend on how I build the bezel. Changing the image is no problem, because I can just change the outline in Corel X3, and do a new printout.

Keeping it in Place
After I get the screen cover completed, I'll have to determine if I need to use some method to hold it in place while I'm driving. I'll need to hold it fully open when the carPC is in use, or -- for short trips when I won't use it -- fully closed.

I plan to put a couple of knobs on the radio image. I think I'd be wise to use relatively flat rubber knobs so they'll serve two functions: they'd look like real knobs when the cover is down, and they'd be bumpers that ride on the dash when the cover is up.

I'm hoping the cover will stay in place simply because of its own weight, and so those rubber bumpers would keep it from rattling. If it looks like it will rattle when it's closed, I'll have to add some small magnets from Lee Valley Tools or DealExtreme plus some matching small steel tabs on the door and the bezel.

Storage
If I can't find the hinge I want, I can eliminate the hinge and simply make the panel removable like f1vlad's in the two previous posts. When it isn't in use, I can slip it down into the space below the bezel for travel. It would probably be pretty easy to devise a mount for it so it stays in place using the same magnets that hold it to the dash.

As long as I keep these possibilities in mind as I build, I should be able to keep from having to cobble together something ugly after it's complete.

Materials and Finishes for the Screen Cover Image

Printing the screen cover image on paper is great for the prototype, but I'll need something tougher for the final product. I have some "plastic paper", which is plastic thin enough to go through a printer, and with a special finish that accepts ink. If that doesn't work well, I'll try to print on the back face of a Tyvek shipping envelope, like those used by FedEx, UPS and others. The trick there might be getting the ink to stick to it. For a fallback, I'll print on heavy photographic-quality inkjet paper.

To adhere the printed image to the cover panel itself, I expect the first try will be with contact cement. Because I want the surface to be very smooth, I'll use the rattle-can version product. I might also try one of the mounting sprays by 3M that are used in framing artwork.

Image protection will be necessary, too. I'm using standard ink from an HP Business Inkjet, so it's not waterproof, and it's not scratch-resistant. One alternative would be to find someone who has a Xerox Phaser color printer, which uses a molten ink which is waterproof and scratch-resistant. I still would want a coating over the finished product.

I think I can protect the image with a layer of clear plastic spray paint, most likely Krylon Fusion. I'll have to do some testing on the printed sheets. If I want to be fancy, I could mask off the gauges and put high gloss on them, with satin on the rest of the cover, but that's as exotic as I'd like to get.

Once again, I find myself thinking of ways to make this way too fancy -- it's just there to fool casual viewers into thinking there's nothing installed that's worth stealing.