Scion xB '06, in-dash Atom 330, Lilliput 889GL; details, pictures, links. Index: pg 1 - Page 7

rdholtz · 05-02-2008, 06:57 AM

Head Unit Brackets

The head unit brackets were going to have mounting tabs that match the deck tabs. But, to be honest, I forgot to include them in the drawing, so I forgot to include them in the metal parts. Instead of making another set of brackets with the tabs, I made add-on tabs that make up for the omission; they bolt right on top of the brackets. I went directly to heavier material for the brackets and tab plates, but these are made from the the web of a galvanized steel stud drywall track. I'd been experimenting with this material and, although it's a relatively light gauge, this seemed like a good application for it. Here are the original cardboard brackets, the metal brackets, and the extra tab plates.

Click images to enlarge.

Here's the head unit with the brackets and tabs bolted on, then the deck started into position, and finally the complete assembly (the deck is inverted in these photos).

I still need to drill the holes in the tabs so I can fasten the HU in place, but I'll wait to do that until I get the speednuts. Putting the extra material (the speednuts) between the tabs will mean a little readjustment, but that will be easy. With the holes in the brackets somewhat larger than a simple clearance fit -- they're 1/4", like the holes in the OEM brackets -- there's a lot of adjustment room. I can move the parts around until the fit is exactly what I want, then tighten the bracket screws down and slip the deck back out, ready for more work on that part.

Because the deck plate has to slip into a relatively tight opening between the head unit and the brackets, I did an assembly-easing trick to the brackets' bottom flanges: I used wide pliers to bend about 1/8" of the rear ends down just a bit so the parts will slide together easily during installation. You can see those slight bends in the bracket photo and in all three of the assembly pictures, but you'll probably have to look at the enlarged view.

I have a little final cleanup work to do on the cooling hole; I'll do that when I'm filing away on the next parts.

-----

This portion of the project has really worked out well. I'm happy with the way the parts fit and feel and look.

Next I'll go to the light sheet metal to make the left leg, the deck support strengthening flanges, and the right leg. Then I start the hardest part: making it all fit in the proper alignment. That's where the inherent inaccuracy in cardboard really shows, and it will take a lot of fit checks as I build parts. Once it all aligns perfectly, I'll make the parts in the heavier steel and do the final assembly.

almera · 05-02-2008, 07:46 AM

Very well organized worklog, nice setup, keep up the good work.

rdholtz · 05-03-2008, 09:08 AM

Quote: Originally Posted by almera

Very well organized worklog, nice setup, keep up the good work.

Thanks, Almera. This is fun, and I appreciate the props.

lostreception · 05-03-2008, 10:51 AM

when u get your prototype done let me know as id be interested in buying a bracket to relocate the HU your work is very good keep it up

rdholtz · 05-03-2008, 12:53 PM

Quote: Originally Posted by lostreception

when u get your prototype done let me know as id be interested in buying a bracket to relocate the HU your work is very good keep it up

I hadn't thought about going into production on these. Maybe a kit would be interesting. Hmmm . . .

Let's wait 'til I get done with this to see if it's something that could be produced easily, or if it would simply be too expensive in production time to be reasonably priced.

turbocad6 · 05-03-2008, 02:09 PM

nice documentation of the project & the thought processes behind it. I did notice mention of concern with a PC DVD drive drawer & interfering with the shifter, have you considered a slot load? the slot loads can go in places you wouldn't normally consider a drive... even if it's not up front & center, the convenience of having it for even the one or 2 times you may actually use it may be worth the consideration...

rdholtz · 05-03-2008, 02:33 PM

Quote: Originally Posted by turbocad6

. . . I did notice mention of concern with a PC DVD drive drawer & interfering with the shifter, have you considered a slot load? the slot loads can go in places you wouldn't normally consider a drive... even if it's not up front & center, the convenience of having it for even the one or 2 times you may actually use it may be worth the consideration...

I agree, a slot-load is a good idea -- that's what's in the existing head unit, and I like it. Since I already have a slimline tray load DVD unit, I wanted to avoid buying a whole new drive for a small convenience. I'd decided to stick with what I have and just add a slimline case.

When I first considered this, I thought the DVD could live in the glovebox and use a Firewire connection (meaning I'd have to add Firewire to the PC). Now I'm wondering if I could mount it externally on top of the PC case and use the slimline-to-IDE converter I have.

Still, there's plenty of room for a slot-load below the head unit. I could easily fabricate a mount. And it would be very, very handy. Hmmmm . . .

rdholtz · 05-05-2008, 09:10 AM

Right Support Leg

This piece turned out to be a classic case of designing something I couldn't build, at least not in my shop, or at least not in one piece. Sometimes it's a long way from theory to reality. In this case, it's a long way from cardboard to sheet metal.

Actually, what this part shows is the limitations of my shop. Compared to the way Original Equipment Manufacturers would produce this part, I use relatively primitive methods: OEMs are automated, while I do everything by hand; they use gigantic machines and a series of dies, while I use small machines and hand tools; they do stamping and some finish work, while I do cutting, bending, drilling, grinding and filing; they do thousands of parts at a time, while I end up with one or two pieces.

But I do have the advantage of speed: they have to go through design, design review, approvals, change orders, tooling orders, setup times and production schedules; I can design, prototype and produce a finished product in a few hours.

Actually, I'm making an unfair comparison. I operate more like an OEM prototype shop -- sometimes known as a manufacturing model shop -- and the products from my shop are pretty similar to what a prototype shop produces: sample parts. If you ever get to watch a prototype-maker in action, it's an experience. The ones I've worked with were masters of their shops, and they quickly knew how to build stuff just looking at the sketches or drawings. The best one -- Frank Moses -- had experience on the manufacturing floor, and taught me to refine my designs so they're easier to make and lower in cost.

So how does all that apply to this support leg? Well, here's where I'd gotten: Version 4 of the basic shape, showing the fastening tabs at the bottom and the deck support arm at the top:

Click images to enlarge.

Version 4 was different from Version 3 because it has added width; I wanted all the strength I could get in this part. I thought I'd add flanges on the front and rear edges, and a doubler plate through the middle of the web to make up for the narrowed area (a doubler is essentially an extra layer of steel; it makes the part thicker and stronger).

Then I took off my designer hat and put on my prototyper hat. It didn't take me long to realize that I couldn't build it in my shop unless I wanted to beat it into shape with a hammer.

I couldn't use my bender to make the front flange (on the left in the photo) because it won't bend just part of a surface; it would bend the arm, too. I couldn't bend the separate back flanges, either, because they're not in a straight line.

Decision time: get bigger, better equipment, or do yet another redesign. Since redesign is an immediate-results, no-cost option, that's what I chose. As it turns out, Version 5 made it much easier to get the whole mechanism aligned.

I had to figure out how to get a part that would fit and still be strong. At its narrowest point, the part is 2" wide. It can't get any wider at that point because it squeezes between the dash and the HVAC system. With that limitation, and with the limitations of my shop in mind, I decided to produce a quickie prototype with 2" channel and add pieces onto it: a separate panel with feet, plus an upper angle arm to support the deck. All the parts were made of light-gauge galvanized steel.

I put the foot panel in place in the car and modified it -- bending, re-bending, nibbling bits away -- until I got it so the feet sat flat on the mounting points without fasteners. I marked for the mounting holes and drilled them (oversize), and bolted the foot panel into the car.

Then I put the main channel in, got the alignment between the channel and the foot panel figured out, and marked them. I took both parts out and riveted them together, and bolted the assembly into the car.

Finally, I put the support arm in place, put the new deck and the cardboard HU in, and marked on the parts where they should connect. Everything came back out and, after drilling holes for rivets to connect them, I got this configuration, seen from both sides:

Boy, that prototype is seriously ugly -- it looks like a stunted toucan. I can promise that the final part will be stronger and cleaner-looking. For now, it works, and I know the most important thing: that I have the final alignment pretty close.

I want to prototype the support arm and tab for the left side, so I can set the whole assembly in the car, put the real HU on it, and be sure it all works as expected. Then I'll refine the alignment, clean up the designs and build the final parts.

The prototype left side parts are next.

rdholtz · 05-07-2008, 08:45 AM

Left Support Leg Prototype

The whole head unit support assembly will have to make up for unfortunate engineering in the vehicle. While the dash is very strong, the HU is moving down into the lower area where there are only a few structural attachment points within reach; the dash is mostly plastic in this area. That means I need a very strong system that makes up for badly located mounting points. This left leg attaches at the back, with only one fastener, so it's cantilevered. I'll build the part in sheet metal, but I'll use a heavy steel lug -- actually a piece of steel plate cut to size -- under the fastener head to keep the part from bending.

Building the left leg was a test of my ability to envision a part, get an outline, and make a single piece of sheet metal into a 3-dimensional part. I knew pretty well what it had to be from my cardboard mockup, so I traced onto paper as much of the cardboard part as possible. Then I added pieces that would make it strong enough to hold the actual head unit, including the flange where the leg will attach to the deck, and a brace that would keep it from deforming under load.

To get it to fit correctly, I bent it, but didn't fasten it together. Once it was in place, I checked for fit and found that the angle was slightly off, and it sat too high (meaning the leg was too long). After trimming the brace twice, re-bending once, nibbling off some of the leg twice, and lots of fit checks, I got it to fit well. I fastened it together with a sheet metal screw and did a final fit check.

Here's the sketch, modified with the changes I made, and the prototype:

Click images to enlarge.

For size reference, the part is 5-3/4" long from the left end to the bend. The blade is 3/4" wide.

Final Left Support Leg

I decided there was no sense waiting to build the final part, so I modified the tracing based on the partially-unbent-and-flattened part, and built the final part in heavier aluminized steel. I used the heaviest sheet steel I had, because this part bears significant load. The trick was allowing for the additional thickness when I made the bends. After a couple of adjustments -- the leg was too long again, and I had to fine-tune the brace -- I got it just right and riveted it together. The back edge of the vertical brace sits firmly against the leg, strengthening it.

There was one change: in the final version, I placed the attachment panel on the outside of the vertical brace, simply because it was easier to put it there, rather than inside. It isn't quite as pretty, but it's a hidden part, so it'll be okay.

Here's the final part:

I'd have preferred to have the vertical support arms come down both sides of the support, but it would have been very difficult to get a screwdriver onto the fastener when I installed it.

The last element of producing this part was to makee the steel lug. It's just a piece cut from a 3/4"-wide galvanized steel bracket. I used an existing hole in the material, so I didn't even have to drill it. The lug is there to spread the load of the large fastener head all the way up the bracket leg, so the cantilevered part won't bend under the rough-road loads it may get. Here's the bracket without the lug, then with both the lug and the OEM fastener:

You can see that the lug adds considerable thickness to the leg, and should make it stronger.

Now I'll go back and make sure everything is aligned well before I produce the final right leg.

rdholtz · 05-09-2008, 04:01 PM

Re-revised Right Support Leg Prototype

I discovered as I was installing this right leg that it can go in from the top instead of having to work it up from underneath the dash. That made things a little easier for all the fit checks. There were a lot for this prototype. It's almost a saga.

I had the new final version of the left side in, but a funny thing happened when I got the prototype right leg in the car with it: they didn't match. Fit checks showed that the left leg held the head unit deck exactly where I wanted it, but that I needed to readjust the right leg's deck support arm so the deck sat level. I also needed to make the front of the arm tapered like the left one, so it, too, was hidden behind the deck's front flange.

To start the rearrangement, I wanted to flip the deck support arm around so its flange pointed toward the outside, as it does on the left support arm. The vertical channel was just a bit too tall, so I cut the top back corner off it to avoid interference. Then I cut the support arm so its taper matched the left side, and started the re-fit. I made changes to both the height and deck angle. I modified, did a fit check, modified, did a fit check, etc., until I'd installed and uninstalled it several times, but I never got it so it fit just right.

I was really struggling to get this thing aligned in the tight space available, so I devised a quick workaround. I bolted two small Meccano angle brackets to the channel, using existing holes near the top, and ran a machine screw and double nut through each of them. That gave me two adjustment points so I could see where the deck support arm needed to be.

Here's the channel and feet with the adjustable positioning screws:

Click images to enlarge.

There was no attachment between the screws and the arm -- I just used them to position the height and angle of the support arm until I got it in just the right spot. Then I marked where it went, removed the temporary angles, and screwed it all together.

It still wasn't quite level with the left support arm. Grrrr . . . . . mutter, mutter, mutter.

Okay, if the easy workaround was unsuccessful, it was time for a different approach. I pulled the Meccano parts off. How about using slots for adjustment? That's what I did next.

I wanted a vertical slot in the channel and a horizontal slot in the arm. I cut the slots by drilling starting holes at each end, then putting a cut-off blade in the Ryobi rotary (Dremel-type) tool, and cutting out the metal between them. After filing them smooth, I fastened the parts together using a small carriage bolt and a wingnut. The carriage bolt has a small square area under the head (see the picture above) that doesn't let it turn in the slot, and the wingnut is easy to tighten by hand, so I could hold the channel and arm in position with one hand and tighten the fastener with the other. Serrated locking washers under the head and the wingnut kept them from slipping. (The serrated washer under the bolt head is a bit larger because the square under the head has to fit through it, where the other one just has to clear the threads.)

Here's how the parts looked:

The camera couldn't see the vertical slot very well, so I outlined it with a marker. You'll see that it ran into a previously-used hole; it's just a prototype, so I ignored that. I did have to make a new support arm, because I'd chopped the old one up so much I couldn't get a slot that would work. That was quick and easy, because it's made of the galvanized steel stud track material, and even has the bend already formed.

I got the assembly finger tight, but loose enough to let move it a little. I installed it in the car and made adjustments and measurements 'til it was perfect, then tightened the wing nut down tight. I marked the outline of the connection point on the parts -- just in case I bumped it out of position later -- and, at last, I had a finished prototype.

The slots worked great. Wish I'd gone down that path in the first place . . .

Here's the comparison -- the old prototype is on the left, and the new prototype is on the right:

Yep, it's still ugly. Perhaps not quite as ugly . . . and it works.

It's time to refine the design and see if I can get strength and beauty into it. Okay, maybe not beauty -- but at least I should be able to produce something that doesn't look like it was made in an 8th-grade shop class . . .

On a side note, that comment leaves me wondering if very many schools still have 8th-grade shop class. It was a long time ago for me, in Homewood, IL. Our shop teacher was Mr. Millush, and I think his primary lesson was to work without hurting ourselves. Safety was the focus; technique was secondary. Every time I use a knife, even all these years later, I can hear him saying, "Cut away from yourself!" And every time I go near a grinder, I can hear him saying, "Wear your goggles -- you only get one set of eyes. Replacements are not available." Good guy. And, apparently, a really effective teacher: I still have all ten fingers and both eyes.

Designing the new style prototype is next.

rdholtz · 05-13-2008, 04:41 PM

More Right Support Leg Shenanigans

I decided it was best to make this part is from two separate pieces joined by rivets. It was yet another redesign, but this is a development process, and sometimes progress is made one step at a time. I wanted the leg clean and strong. The two-piece design gives me the strength of a doubler and the flexibility to place flanges almost anywhere I want, even with my limited shop equipment.

I was impressed with how easy it was to get the slotted parts aligned, and I decided to use that same approach in these new parts: I'll make the slot(s) to hold the prototype parts together until I'm sure they're perfectly aligned, then mark them and make changes in preparation for the final heavier-steel parts. The precision of a manufacturing plant is simply unavailable in my shop, and I have to keep making allowances for using primitive equipment.

So it was time to go backwards, a bit, and make a cardboard mockup of this new prototype, just to be sure I can make it work. Here's the design translated to cardboard. On the left are the parts, and on the right arte the parts as they'll be fastened together:

Click images to enlarge.

The upper panel, seen on the right, contains the flange on the top of the support arm. I had originally put an opposite-facing flange all along the back of that panel, but there's a conflict with the HVAC box, so I deleted it (with scissors -- that's one of the good things about using cardboard). The lower panel contains the flanges all along both front and back.

The two-piece design gave me options for getting it to fit just right when I installed it, because I could change the relationship of the panels to get precise fit. I like designs that give me options. In shade-tree engineering like this, sometimes we come upon roadblocks, and options make it easier to figure a way out. In this case, I could change the fit of the part instead of remaking it.

When the head unit is installed on this leg, the back foot is always in tension, and the front foot is always in compression. The feet have to be strong, so I've made each foot from two overlapping tabs; the upper one is pretty much an extension of the flange. This way the feet have support from two directions at right angles to each other.

One addition to the part in final form will be a right-facing flange flange along the back of the upper panel (there's room for one facing that direction). It will stop where it meets the lower panel, and I'll rivet the two flanges together there -- an easy way to add strength.

Next I'll make it in steel.

rdholtz · 05-14-2008, 01:06 PM

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.

turbocad6 · 05-14-2008, 02:22 PM

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...

rdholtz · 05-14-2008, 07:03 PM

Quote: 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.

-----

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.

rdholtz · 05-15-2008, 04:13 PM

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.

User Name		Remember Me?
Password