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

What the New Side Panels Will Do

The whole point of going backwards in the install -- back to making new PC chassis parts -- is to eliminate the cable hassles. It's just too hard to get the PC into its bay and be comfortable that all is well. I don't like operating blind, like I had to do when I installed the system as I built it. I couldn't see what was happening back inside the dash, and I wasn't comfortable just applying more force to push the chassis in.

I found myself finding other things to do, rather than tackle installing the PC in the dash. When I realized I was putting it off because the process was misery, it told me I needed to do a redesign.

There are three issues here:

1. When I turn the power on, I don't want to hear "Bzzzzzzttttttt".
2. I want to install the carPC, not cram it in a hole and hope it will work.
3. I want to enjoy the installation, not dread it.

The new sides should resolve those issues.

With the redesign, I've raised the mainboard -- which sits about halfway up in the chassis -- about 1/4 inch (~6mm), so it rides slightly above the notch (see the photo in the post above). I've raised the bottom panel and the attached hard drive about 1/2 inch (~13mm). The sides are the same height, so there's 1/2 inch of space below the bottom panel. I'll need to reduce the depth of the bottom panel 1/2 inch to give the cables a place to enter the chassis. I'll pad the edge where the cables rub with some split tubing.

At installation time, I'll pull all the cable ends out so they're hanging out of the PC bay. I'll slide the case in over them, fasten it in place, and attach the cables to the mainboard. The cables will all do a 180 degree turn to get into place; they're all capable of that -- I've checked.

When the cables are all attached, I should be able to swing the back panel of the chassis down on its hinge and mount the touchscreen on it. With that accomplished, I'll be back where I was with the original design, but with a PC system that's far more maintainable, changeable, and upgradeable. I'll still have to pull the chassis out to add memory or change jumpers, but that wouldn't happen very often. No matter what, installing the chassis should a far easier and faster job, and not one I dread.

We'll know soon . . .

Punching the Side Panels

After using the spring-loaded centerpunch to make dimples at the hole centers, I went to drill the new side panels. As I put the 5/32 (~4mm) bit in the drill press, I thought, "Hey, I could punch these." I put the drill bit away and got the punch out.

I can't say enough good about this little, inexpensive hand punch I use. It's $19.99 from Harbor Freight, and it's a terrific tool. It comes with a range of punch sizes and a case, and I'd hate to be without it.

I also have its bigger, deep-throated sibling for heavier or deeper work, but find I rarely need it. The little one does just fine, and goes through aluminum panels like they're butter.

I used to drill all the holes I needed. Then I tried using a punch. OMG. The holes are perfectly round, perfectly sized, and right where I want them, and they require absolutely no edge finishing. The only mess is the little disk punched from each hole.

It's even pretty quiet. For instance, I did the 16 holes in the side panels at night over the wastebasket in the kitchen, and it was quiet enough that I didn't wake the girls sleeping 20 feet away with the bedroom doors open.

It's fast, too. In five minutes, I got the tool out, changed the punch and die size, did the punching, and put the tool away. No muss, no fuss: I was done and ready to go assemble the chassis. If I had drilled the holes, I'd have had to go run the finish reamer around each hole, both sides, to clean them up. The result would be less-precise holes and a lot more chips.

That punch is a really good tool -- worth every penny and more.

Changing the PC Power Connection

There's one change I hadn't planned, but was forced to make: the power port I made for the previous design simply doesn't fit in this redesign. It's so bulky that it interferes with one of the data ports, no matter where I mount it. I guess I wouldn't mind if one or more of the parallel, serial or PS/2 ports was blocked, since I have no plans for them. But I still wanted to devise something significantly smaller than the monster panel-mounted connector I used on the original design. That was great for a system that was attached to the chassis, but there's no room for that, now, and I wanted something smaller and more flexible.

I still wanted a simple push-pull connection, not something that took a screwdriver. There are all sorts of connections available, but many of the things I considered used 18 or 20 gauge cable -- lighter than I wanted for this. I dug through the myriad parts we have stored in the garage, and looked through scrapped server parts at work. I even browsed the Radio Shack online store, and had about decided to just go to the local Radio Shack for some Molex connectors.

Then I asked Josh for his ideas, and he came up with the answer almost immediately: a 6-foot (~1.8m) cable for a power distribution unit. Here's what the ends look like:

I'll use it with the female end (on the right in the image) connected to the PSU, so there are no exposed power prongs hanging around in the dash when I pull the PC out.

I'll chop the cable about 10 inches (~25cm) from the female end, split the wires apart for about 1.5 inches (~40mm), solder on some forked connectors, and screw them down on the PSU. I'll attach the cable to the side panel of the PC chassis with a tiewrap through an adhesive-mount base.

I'll put the male end of the cable in the PC bay, and run the cable down to the wiring box, where I'll split the wires, solder on blade connectors, and plug them in, replacing the old power cable. Then, when I'm ready to connect, I'll just put the two plug ends together, and the PC will have power. Easy enough.

It's just what I wanted . . .

Changing the PC Power Connection -- Oops

Well, there's one thing I was wrong about in the post above. I wrote "I'll attach the cable to the side panel of the PC chassis with a tiewrap through an adhesive-mount base." When I started to make the cable, I realized the PSU is on the top panel, and I have to connect the cable there; if I connect it to the side panel, I won't be able to take the top off the chassis.

So I'll change the plan, and attach the power cable to the top panel. There's no room for an adhesive tiewrap mount, so I'll punch a hole and rivet on a nylon tiewrap mount.

PC Power Connection Installed

Well, I was wrong again. I said, "There's no room for an adhesive tie-wrap mount". But, with a little different routing, there is room. In fact, there's room for two of 'em, and everything lays in there very nicely. Here's the way the finished top panel looks:

Click image to enlarge.

As I originally intended to place it, the power connector would have been shorter -- just hanging off at the top of the image. But I realized I could put an adhesive connector in the middle of the board, and that would let the power connector come out over the unused parallel, serial and PS/2 ports, where there's not much chance of it blocking anything.

That mount is directly over one of the holes used to mount the end panel, so I lined it up with the hole in the adhesive mount, and it should be fine; the mounting machine screws are long enough to take that extra depth. To get it in place, I had to trim a little off the adhesive mount closest to the PSU -- the one at the top of the image -- but only about 1/8 inch (~3mm).

You can see that the ATX cable is far longer than necessary, but I decided not to shorten it. Instead, I just left it in the snakeskin and doubled it onto itself, then held it to the top panel with a tie-wrap that goes through a nylon base riveted to the panel through an existing hole. The connector is positioned so it's in just the right place to connect into the mainboard when the system is assembled.

Lucky Strike

Once in a while I get really, really lucky, and that happened today. Before I left for work, I decided that I'd look over what it would take to get the new power cable up from the wiring box to the new PC power plug. I wanted to figure out how much cable sleeve I needed to strip back, how much wire was needed inside the wiring box, and so on.

I looked at the old plug. Hey, it's the same as the one I was planning to install! Awwwwright!

I'd completely forgotten that the power port I used previously was taken from a dead power distribution unit. That part of the job is done without lifting a finger. Now I just add the USB cables, and I'm ready to start the installation.

I like gettin' lucky . . .

(Or is this whole "luck" thing just a matter of memory failure? Hmmmm . . .)

EDIT: I just talked to Josh about this. He remembered the original plug, and that's why he recommended the PDU cable. So it wasn't luck, after all -- just his good guidance. And my bad memory.

I still feel lucky . . .

USB Ports -- Again

The last piece of the new-chassis-design puzzle is the four additional USB ports that plug into header connections on the mainboard. I'll build a bracket for them, but for the test installation, anyway, I think I'll simply plug them into the mainboard and connect them to the side panels of the chassis with tie-wraps. That will leave four USB heads hanging out in the connections area. There will be a lot of connections in that space, but it looks like there will be enough room.

I can build the bracket and install it later. I've bent a 9-inch (~225mm) piece of 1/2-inch (13mm) aluminum angle, made 90-degree bends on the ends to form mounts, and marked hole locations for the USB ports and their attaching screws. Now it's some drill and file work, and I'll have a bracket.

That should leave the PC pretty clean in the ports area. I thought I'd like to shorten the cables some, but that would require a lot of fine solder joints and shrink tubing; all those joints would add enough bulk that I might be better off to leave them long.

I'll work on the bracket later today. Josh and I are hosting a get-together of people interested in RepRap, so that'll take most of the afternoon. It'll be a very interesting session.

Afterward, I'll see about finishing the bracket and getting everything assembled. With a little luck, Sunday is install day.

looking good there rdholtz as usual
i like the hole puncher really nice tool use it also all the time if the material isnt to thick
goodluck with the always improoving project :P

Originally Posted by vincenttor

looking good there rdholtz as usual
i like the hole puncher really nice tool use it also all the time if the material isnt to thick
goodluck with the always improoving project :P

Thankee, sir. We're getting close to the next test installation. Yippee!