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

Using Lightweight Sheet Metal

I wrote this morning that I had acquired some light (22-gauge) aluminized steel. I can use this material two ways: (1) because it bends easily even with lightweight benders, it's very good material for prototyping parts; and (2) it can be used for final parts because it's so strong when formed into something like the chassis, which is boxed on almost all sides; only the back is open.

If I use this for final parts and have some strength concern, I could simply add a doubler panel in those areas I thought might be weak, or I could add 1/2 inch (13mm) of material and fold a doubler in on itself; no extra fasteners would be required.

I think I'll give this material a try with the next parts I form, instead of waiting for version 2. It will be about the same weight as the thicker aluminum I've been using, and it's going to be a lot easier to form and work with. I don't see any reason it will be less successful, since the parts I've made to date are so outrageously over-engineered. The lighter stuff may not be explosion-proof, but I'm hoping I never get to test that capability anyway.

Originally Posted by animantoric

I know the cooling discussion was a month ago, but I'm new to the forum and just now read it. I also picked me up an xB last week, so I love seeing what others have done. Anyway, since you said that you keep the climate fan going most of the time, you could route a small duct from the recirc inlet behind the glove box to your case. That would ensure air removal from the dash while in recirc mode. This way you wouldn't have to mod a bezel at all (even though it's already modded). The other day I was cleaning out the car and pulling out the previous owner's Sirius FM mod and realized just how hot the inside of the dash gets. Not quite untouchable, but not comfortable at all. Anyway, just wanted to throw in my thought while I remembered...

I checked out the possibility of adding that duct, and decided it simply was too much trouble for the benefit. A much easier approach would be to attach a fan at the bottom of the dash and blow air from the cabin up into the dash; it's all open, anyway.

In addition, I'm going to try forcing air from the chassis out around the screen, so there's constant motion of air from dash into cabin and back around. I'll experiment to see which way to blow the air for most effective cooling.

Although I've made extensive mods to the bezel, none of the changes I've made will work with the new in-dash installation, so I'll be modding it again.

Good luck with your xB -- I've had a great time with mine, and have many miles to go before I "finish" the installation (they're rarely ever finished).

Matched Hole Tooling

When I wrote about making holes in post #573, I mentioned I planned to make a pattern plate to be sure the holes align during assembly. I made one for testing last night.

There are four main dimensions used on the panels: 4.5 inch (height of the chassis), 5 inch (depth of the bottom panel), 7 inch (width of the chassis), and 9 inch (depth of the top panel). All the panels have holes 1.25 inch (about 32mm) from the ends and 3/8 inch (9.5mm) from the edge. The longer 7-inch and 9-inch sides get a middle hole, too.

Although holes are not shown for the 4-1/2-inch end panel, you can see most of those hole patterns in the chassis here:

Click images to enlarge.

To get consistent hole positions, this is the sample hole pattern plate I made:

The holes in the template are 7/64 inch (2.8mm), just large enough to let the centerpunch go through to the part. I align the arrow end of the template to the end of the part, and the bottom of the template to the edge of the part. Then I put the spring-loaded centerpunch in the hole. When I press it down, the punch puts a hole-guide dimple in the part. I repeat as necessary for the other holes.

When it's time to make the holes, the dimples guide the tip of the hole punch or the drill bit to the exact location of the hole.

The numbers on the pattern indicate which holes to use for a part. All the parts use the hole on the right end. Parts that are 4.5 and 5 inches long use the single additional holes marked for them, and the 7-inch and 9-inch parts use two more holes marked for them.

Using this template means I won't have to measure and mark each individual hole position; I'll just align the pattern on the part, make the marks, and get the hole punch out. If I do it right, all the holes will line up at assembly time.

That will be the real test. We'll see how well it works then . . .

Fan Change

I haven't made the top panel that will hold the fans in the chassis, and that turns out to be a good thing.

I originally wanted to use 1.5-inch fans, but, after I got holes for them into the Sketchup design, I looked a little more closely at the fans. I realized that they're 3/4 inch (19mm) deep. That's just too deep, but we don't have any 1.5-inch fans in the store that are slimmer. I decided to go to the 52mm (slightly over 2-inch) fans we have; they're thin enough -- about 1/2 inch (13mm) -- that they allow pretty good flexibility in positioning the boards in the chassis. I'll have to change the Sketchup drawing to accommodate that.

I had originally intended to splice the wires from the two fans so they run off the same mainboard power port, and are controlled by mainboard temperature. But there's a potential issue there: if the mainboard stays cool, the fans won't run, so they won't be cooling the LCD panel, either. I'd have to monitor the monitor (pun intended) to see if it got hot.

Instead, I'll have one of the fans connected to the mainboard, and the other will be connected to the 12V rail, so it will run all the time. I'm hoping that will give the best of both worlds: a constant flow of air to cool the LCD panel and keep chassis temperatures relatively steady, and big cooling when I need it, like startups on days when it's been sitting in the sun.

Originally Posted by mcm

Weld it.

I'm not quite sure what you mean. Welding aluminized steel is a nasty process, unless you use spot welding, and I don't have a spot welder. Since some of the parts are aluminum, they can't be welded to the steel.

Welding sheet metal -- say, by using a MIG or TIG system, is a process that I've only witnessed. It takes a fine touch with a pretty expesive welding rig, and I'm a novice welder.

I coud "weld" it with JBWeld, which is an epoxy, but that would be permanent, and these projects are always changing; being able to disassemble is a good thing.

I'd rather stick with machine screws and rivet nuts.

Originally Posted by rdholtz

I'm not quite sure what you mean. Welding aluminized steel is a nasty process, unless you use spot welding, and I don't have a spot welder. Since some of the parts are aluminum, they can't be welded to the steel.

Welding sheet metal -- say, by using a MIG or TIG system, is a process that I've only witnessed. It takes a fine touch with a pretty expesive welding rig, and I'm a novice welder.

I coud "weld" it with JBWeld, which is an epoxy, but that would be permanent, and these projects are always changing; being able to disassemble is a good thing.

I'd rather stick with machine screws and rivet nuts.

I have never done much welding work, but what about an arc welder? Also have you thought of a epoxy? I used aircraft grade epoxy on my roof plate for the 15 inch flip down. It has never budged, or chipped or anything, even with the fast driving conditions I put it through.

JB Weld can come apart sometimes, Using Aircraft grade is better. Not sure where to buy it though. I went to a welding shop and after fighting with them to weld the plate and them refusing, they said the aircraft grade will work just as well.

PS: The aircraft grade epoxy is veryyyyyyyyyyyyyyyyyyyyyyyyy strong smelling and I think toxic, so make sure it is an open area for at least 2 days. I learned the hard way with a smell being trapped in my house for 3 weeks.