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

Making the Right Support Leg

As I was marking up my cut lines on the sheet metal, I realized that I hadn't refined the feet; that is, I hadn't gotten them exactly the shape needed to eliminate any interference with objects in the mounting area. I reduced the size of the tabs that form the feet, changed their shapes a little to make the two tabs for each foot fit together well, and added a little dimension to the flanges at the bottom so the cut lines would be smooth. I'm no pro at this -- I learned sheet metal work doing this carPC project -- so a lot of this is by the seat of my pants. I just try to envision how things go together and make them the right shape so they'll bend into shapes that fit and work well. It requires some 3-D thinking, and laying that 3-D idea onto a 2-D sheet. Interesting stuff.

I'm hoping it isn't a mistake to feel so confident of this design that I've gone directly to finished steel. We'll see. These parts are made from the steel side panel from a server, and they're painted light gray on one side and dark gray on the other.

Here's the rough-cut blank for the panels, cut off the full panel with a saber saw, because the full panel won't fit into my small band saw. If you enlarge it, you can see the scratching that marks the shapes:

Click images to enlarge.

Here are the rough-cut parts, and then the filed-down parts, with a few minor changes from the blanks to account for things I recognized as I filed them smooth:



As I was preparing to bend, I realized the back flange on the upper panel would conflict with the bender when I bent the top flange, so I cut the top flange back far enough to allow the piece to fit in the bender. It reminded me that I can make bends in cardboard with my knife and ruler that I can't make in steel with a bender.

Here are the bent versions, showing the bending progression:



I thought I snapped a shot after bending the first of the foot tabs -- that would have been between pictures 3 and 4 of the series -- but I apparently forgot. The tab connected to the flange gets bent in first because it will be above the foot tab. I just use heavy lineman's pliers for this, because they have a broad mouth that grabs almost all the way across the bend. Bending it with pliers doesn't make a very tight bend, so I clamp it in the vise and give it a few love taps with the speed wrench -- also known as a hammer -- to make a good, sharp bend. Then the panel tabs -- the actual feet -- get bent up much the same way. Again, I finish up with vise and hammer to make tight bends. It's primitive, but it works.

I won't bend the back flange on the upper panel until I mark the fit. Then I'll trim away the part I don't need and make that final bend.

Now it's time to start the fit checks.

doesn't it suck to have to sometimes do stuff by hand with just basic tools, spend almost countless hours to produce something that you know that the right machinery can pump out many of the same pieces over & over each minute if it was a production piece

that's the meaning of custom though... you could spend many hours fabricating a one off plastic piece that in the end may cost you hundreds in both time & labor & materials, where if this piece was produced it would cost peanuts...

Originally Posted by turbocad6

doesn't it suck to have to sometimes do stuff by hand with just basic tools, spend almost countless hours to produce something that you know that the right machinery can pump out many of the same pieces over & over each minute if it was a production piece

that's the meaning of custom though... you could spend many hours fabricating a one off plastic piece that in the end may cost you hundreds in both time & labor & materials, where if this piece was produced it would cost peanuts...

Funny you should mention that. I was just muttering to myself about the number of hours I have in this development process, and all just to move a lousy head unit. But I realized that it's a lot of fun to make new designs, learn new skills, and wind up with a product that's seeing the light of day for the first time anywhere. I like to write about the process, to help other people gather ideas on how they can do it. It's good to be a resource when I know enough to help others.

We're pioneers, in some ways. As one wag said, "It's easy to tell the pioneers: they're the ones with arrows in their backs." But all the while we're trying to dodge the arrows, we're having a blast, because we're out here on the edge of sanity and reason, where the air is fresh, the wind is strong, and the challenges make our brains dance.

This is fun stuff. I like solving problems, including problems I make for myself, and including the problems of having primitive equipment, insufficient experience, and little more than a vision to go on. I like saying, "I wonder if I could do that . . ." and then finding a way to get it done.

I can't help myself: I like it. Send me in, coach.

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EDIT: Oh, and one other thing -- I want a PC in my car. This is the only way I can figure to get what I want, done as well as I want, and that does what I want when I want it to do it. Nobody makes it, so I gotta do it.

Fitting and Fastening the Right Support Leg

The first step was to mark for and drill the fastener holes in the feet, and then get the lower panel bolted into place. I marked a cross through the fastener holes in the car, with the marks long enough that I could put the panel in and still see them. Then I drew continuations of those same lines on the panel feet, and took the panel to the drill press. I marked the centers with a center punch, drilled 1/8" holes, and then drilled the full-size 11/32" holes. There's not much slop there for a 5/16" bolt. Here's the progression:

Click images to enlarge.

After I bolted the lower panel in, I tried to put the upper panel in place. Hmmmm: I couldn't get it in. The back flange -- the one I was going to wait and bend after I did the fit checks -- conflicted with the HVAC unit; it made the panel too wide to fit. If I'd thought about it, I could have figured this would happen. I had to make the narrow area in the support leg because of that same conflict with the HVAC unit. DOH!

So I had to make an approximation of where that flange would end, and cut up to it. I left some extra length on it, and bent the extra out of the way. When I get the final configuration, I'll take that extra section and attach it to the other panel -- just a little extra support. There's no such thing as too strong, as long as stronger doesn't mean a lot heavier.



I put the upper panel back in place (approximately), got the deck roughly level, and marked on the panels so I could duplicate that position on the workbench. Then I went to the bench, determined a location for the adjustment slots, marked the start and end holes with a center punch, and headed back to the drill press to make an 1/8" hole in each end of the slots. Then, after some careful nibbling with the Ryobi rotary tool, I would have had nice, clean slots. But I blew it.

Note of caution: be careful with that rotary tool. I was simply running the Ryobi along a bar to guide it as I made these slots, and that worked great on the lower panel; I got a nice, straight slot. But the 18V battery was getting low, so the RPM level was sinking, and I changed batteries. Oh, boy, then I had lots of RPM. I just touched the bit to the steel and it went berserk, made a quarter inch hole, and snapped the bit. "Well, damn. It never did that before." So there's one end of my slot that got Real Fat and Real Ugly (in the picture below, on the left).

I confess that I wasn't paying as much attention as I should have -- I gotta be more careful here. Mr. Millush would be using this in shop class as a good example of a bad example. I would have destroyed both the bit and the part, but the panel will be hidden, so I only lost the bit. Luckily, the broken end of the bit put a ding in the garage wall, not in me.

It could have been worse, but it was still a major Oops. I gave myself a talk about shop safety and paying complete attention to what I'm doing, especially when messing with very high rotational speeds. Then I went back to work.

I finished forming the slots, did some hand filing, and was ready to assemble. I pulled the adjustment fastener system out of the prototype and put it in the new assembly, and was ready for final fitting.

Here are the slotted pieces and the assembly, ready to install:



I put the system in the car, found the right position, and tightened the locknut down. Then I pulled it out and put a single additional hole through both panels, and put a sheet metal screw in to lock them together.

Now that I have the exact relationship between the assembly's parts, I could rivet them together, but -- just to be sure I don't need any final adjustments -- I'm going to leave it in this form until I get all the remaining holes drilled in the other parts and everything lines up just right.

Those finishing steps are next.

Almost Done

Before getting the deck mounted, I wanted to finish the tabs that hold the head unit onto the deck, because I finally remembered to buy 6-32 speednuts at Home Depot. I slipped the speednuts onto the deck tabs and filed away a bit of the speednut corner to make it conform to shape of the deck tab. I marked the hole locations through the speednuts, and drilled 5/32" holes. I slid the head unit and bracket back onto the deck, marked through the deck tab holes to the bracket tabs, and took the bracket tabs off and drilled them the same size. I assembled everything with the tab brackets just a bit loose, and made sure there was a gap of 1/32" or so -- less than 1mm -- between the bracket tabs and the speednuts, and then tightened the brackets down.

Here's how it looks from the bottom with the head unit fastened to the deck:

Click images to enlarge.

Dimple Laboratory

Next it was time to fasten the deck to the support arms. I marked for fastener locations on the support arms -- centered on the arms, 1" and 4" back from the front of the deck, and drilled 5/32" holes there. I put the deck where it would go, and marked through the support arm holes to the deck, measured the locations to be sure they made sense, and drilled 1/8" holes in the deck.

Because I needed to keep the deck surface completely smooth, I wanted to use 6-32 x 1/2" countersunk-head machine screws and nuts to attach it; I didn't need the extra length, but it's easier to work with them in a cramped area when they're a little longer. The machine screws make it easily removable. Then I had a problem: I don't have dimple dies to make the dimples in the sheet metal that would allow me to use countersunk fasteners. Time to get creative.

I know that dimple dies just squeeze the area around a hole and stretch it downward. How could I do that? Let's see -- what if I took a fastener that had the right size head -- or maybe slightly larger -- and used it for the male die? I knew the hole in the sheet metal was going to grow as the metal stretched downward, so I needed to make allowance for that. I had to start with a smaller hole, which meant I needed a smaller shaft on the die. I found a countersunk-head screw with a big head and a smaller-than 6-32 thread, and that became the male die.

Then, for the female die, I needed to make a countersunk dimple in something. It had to be larger than the matching male die to account for the sheet metal squeezed between them. I thought of using a piece of wood. Could I just whack a larger fastener into a piece of plywood, or, better yet, particleboard, which is somewhat harder than plywood? Some experimenting on scrap showed that I could do that, but it's very imprecise: I couldn't get consistent results, and the scrap sheet metal parts ended up bent in ways they weren't supposed to bend.

Okay, how about steel? Angle irons and hinges have countersunk holes. How would they be? After some more experimenting, the answer turned out to be "only okay, at best," since I didn't have the size hole I really needed. So I got a piece of steel, drilled the right size hole, and chamfered it to the right size with the end of a drill bit. Result: one female die.

Some good ol' shop violence -- with a hammer -- produced good results on some test pieces, so I made the countersunk holes in the deck the same way. Sure enough, the 1/8" holes grew enough to work fine with the 6-32 screws.

Here are the countersunk holes in the deck:

Click images to enlarge.

I drilled the support arm holes out to 5/16", which was just large enough to allow the countersunk metal from the deck to nestle into the holes. I put the arms on with the 6-32 x 1/2" machine screws, fastening each with an external-tooth serrated washer, a flat washer, and a 6-32 nut. The deck metal actually protrudes through the support arms a little, and the serrated washer grips well while it fills the gap. I tightened 'em up, and the deck was attached.

Final assembly and a photo shoot, coming up as soon as the camera is charged.

wow lotsa work going on here i wish it were easy even witht he detailed instustions o dont think id be able to recreate what youve done but if you have free time and want to imrove even more on you design id love to see the prototypes. can wait to see it in place

Originally Posted by lostreception

wow lotsa work going on here i wish it were easy even witht he detailed instustions o dont think id be able to recreate what youve done but if you have free time and want to imrove even more on you design id love to see the prototypes. can wait to see it in place

Well, it's in place -- I'll be writing up the worklog tonight. After all the design work, cardboard parts, prototypes, and final parts, plus all the stuff that just didn't work and had to be revised and re-revised, it's done. It's kind of sad that not a bit of the work shows. Installed, it looks like it belongs there: OEM.

I should have the log and pictures up tonight or tomorrow, depending on my work schedule.

Originally Posted by lostreception

i'd love to see the prototypes.

The prototypes are nothing to look at, really -- just what you see in the pictures. The steel is so light that they aren't strong enough to carry the head unit load in operation, and so they're only for positioning. The deck, head unit brackets and left arm never even got prototyped; they just went from cardboard to steel. The right leg prototypes are interesting to look at, but they don't fit as well as the steel final leg because I did the post-prototype refinement in the cardboard re-re-revision.

Now that I have a design that works, a good sheet metal guy should be able to crank these parts out pretty readily. I would recommend that the legs should be made just a bit shorter; that would allow for shimming in other cars, since units even of the same car are slightly different.

If I were to do a second version, I'd change the deck to allow a slot-load DVD player to mount below the head unit. But that's another development process . . .

I don't think a production version will be in the works; the first version of the Scion xB is no longer manufactured, and this wouldn't fit anything else. With all the parts involved -- deck, two brackets, two support arms, and fasteners -- it wouldn't be a cheap kit, and risking a production run on an unknown market probably isn't very wise.

Assembled Support System

I reinstalled everything in the car and confirmed proper fit, then pulled it all back out and riveted the right support leg. Before I forgot, I traced the leg for future reference. Here's the final leg:

Click images to enlarge.

Then, just to give an idea of what the whole thing looks like, I assembled all the parts I'd made. Here's how the completed assembly looks out of the car. It's upside down in these shots, from the left and the right:



. . . and here it is from the front (upside down again) and the top:



Then I fastened the head unit into its new home. Here it is, from the right and left sides (still upside down):

Click images to enlarge.

. . . and from the front and back:



She goes into the car permanently, next.

Permanent Installation

The support assembly couldn't be installed as you see it in the post above; it had to be disassembled and then reassembled in the car. I got the left and right legs in, and then put the deck on them.

Attaching the deck was a trick. One thing I'd change about the deck-to-support fasteners: next time I'd use locking insert nuts with plain washers (I didn't have the locking nuts in my shop, so I went with what I had). The combination of three pieces -- serrated washer, flat washer and nut -- was tough to line up in position in the tiny space available, and just two pieces would probably be somewhat easier. It would be nice to just use the nut alone, but something has to take up the additional thickness -- the nut alone wouldn't fill that gap.

Because of the fastener issue, the final installation was more time-consuming than would be acceptable in a factory situation, but for custom work, it's okay. I got it all installed and checked for fit one last time. Phase 8 was relocation of the head unit, so Phase 8 is Completed.

Here's how the head unit looks in its new home:

Click image to enlarge.

You can see that the dash is stripped back to bare bones. Underneath the head unit, the cigarette lighter and the passenger airbag indicator are functional, but just hanging around, right now. I expect to make a simple plastic insert to fill the area around the head unit, one that will provide a place to mount the both the lighter and airbag indicator, and perhaps a USB plug or two. It will clip in separately from the bezel, much like the OEM Scion cubbyhole unit did. ***Edit: If I can find a spare Scion cubbyhole unit, I'll use parts of it, especially the framework with the clips that plug into the dash, and maybe even the face part that holds the lighter. ***

Connections

This new support system is set up so the head unit can go in and out with just two screws, so pulling the head unit out to make the wiring connections should be pretty easy. Before I can make those connections, though, I need to extend the head unit wiring from the old location down to this new one. That's next.