Because these parts are all being built by hand on relatively light equipment, holding tolerances of a few thousandths of an inch is pretty tough; there's a lot of "eyeballing" going on. With planning, practicing and really careful measuring, I'll still only get close to the precision I used in Sketchup. And we can bet that, even after tests on waste pieces, I may scrap a part or two before I get the final panels.
I don't want to use "almost" parts. Even though it will be hidden in the dash, I want the chassis to look good. But I have to be realistic: the end result will never look as perfect in real life as it looks in Sketchup. It's not even going to look as good as the chassis that Blk02si produces on the CNC gear; his parts always look immaculate and do what they're supposed to do, so he's he's the guy I want to emulate.
From a production standpoint, the end panel is going to be the real trick, because it has bends on all four sides. Just getting flanges on two opposing sides exactly the right distance apart is a trick; getting two more opposite bends just right is going to be a real challenge. That will be the last piece I bend; I'll use the others as warm-up parts, and I'll do a bunch of test bends on scrap.
I started on the easy parts -- the side panels -- because they have no bends, so they're a great warmup after several months of being away from fabrication. It feels good to be back in the shop again.
I'm back into production on the carPC chassis, and pretty excited to have it coming along.
More about that later . . .
More Parts Cut
It was a good night in the shop. I got the other side panel cut to size and the edges filed smooth, and I got the mainboard support brackets cut to size, filed, and bent. Although the finished mainboard supports will be only 6.75 in. (171.5mm) long, I bent them before cutting them to length, so they're 9 in. (229mm) long right now. The bender easily handled the 9-inch bend in 18-gauge (.042 inch, or 1mm) aluminum.
I'll cut the PSU brackets and the top and bottom panels next. But I'm running out of material; I only got four panels of the aluminum, and the last two will have to be for the top, bottom, and the PSU support brackets. Unless I can scrounge up more aluminum, I may have to use aluminized steel -- which I have plenty of -- for the end panel and the monitor support. Even though the aluminum parts and steel parts are dissimilar metals, the "aluminized" coating on the steel means it plays nicely with aluminum, and presents no galvanic corrosion issues. It means using aluminum rivet nuts will be fine, too.
Here are pix of the parts I made the first two nights. These are the side panels and the mainboard supports.
The mainboard supports are still 9 inches (229mm) long; they'll be cut to 6 3/4 inches (171.5mm) before installing. In the second picture, I put them in position to show how they'll mount. I expect they'll end up about 1/2 to 3/4 inch (13 to 19mm) from the front panel (that's on the left in the upper one), leaving plenty of open space for cable connections at the back.
After I get them done, all the parts will get a final scrubbing with a 3M abrasive pad to give them a uniform brushed look.
Tonight I got the rest of the bottom panel cut to size, and blanked out the end panel, which is going to be the toughest piece to produce. It needs to be exactly right in the final dimensions, because everything connects to it.
I screwed up on material. I made the sides, which have no bends, from aluminum, but miscalculated how I'd cut the parts, and ran out of aluminum. I ended up making the end panel -- the crucial one -- from .035-inch (9mm) aluminized steel. I'd have been a lot smarter to use the steel for the no-bend side panels, and use the aluminum that bends so nicely on the end panel.
Big oops? Well, that'll depend on how the bending goes. I'll practice bending the flanges on some scrap before I go for the actual panel. I'm still relatively new at this -- I'd never worked in sheet metal 'til a year ago -- so I have to test things before I bend. And I've taken several months off between bending sessions, so I'm a bit rusty on technique. I haven't done so much of it this round that it feels natural again, so it's a more methodical process because I have to think out every step of producing the parts.
The End Panel is All Bent Up
I just couldn't quit last night without trying to bend the end panel, so I went back down and worked some more. I did a lot of calculating and some test bends, and finally gave it a try. I was resigned to scrapping the first one, figuring that would be the "learner" piece. But it came out fine on the first part. Amazing.
This morning, I was still fired up to work in the garage, so I made the blanks for the PSU mount brackets. They're cut to width, but they're not cut to length yet. I made them wide so I can use two fasteners where they mount to the sides; there's only one mount on each end of the PSU, so I needed to be sure they won't twist out of position.
And I got lazy on these. The scrap from one of the aluminum pieces I used (from a dead IBM tape drive) already had a 3/4-inch (19mm) flange on it, so I just used that piece, flange and all. I had to do was cut 'em on the bandsaw and get busy with the file.
Here's how the parts look:
Shorter PSU Brackets
Those very long PSU mounting brackets -- the ones pictured in the previous post -- got shortened up tonight. The mounting holes will be 5/8 inch (16mm) from the inside surface of the side panels, so the brackets only come in 7/8 inch (22mm), half as far as they do in the picture. It looks like they'll be mounted with the flanges pointing down, where the mainboard bracket flanges will point up.
This is more of a testing night than a building night. I plan to do more testing to see why I'm getting so much variance in my bends. I'll crank on that until I'm too tired, and then I'll hit the shower. I'll report on the results tomorrow.
This is turning out great, exactly like your sketchup drawing..... Maybe I should get into trying to use sketchup, although with me, when I seem to plan things, everything goes wrong. Its easier to just pull it out my head as i go along.
Nirwana Project, the Android/Win 7 hybrid system!
1X Ainol Novo Flame Tab
3x Perixx Touchpads
3x 7 inch Screens
1X 7 inch motorized Screen
1x Win 7 PC
For this chassis project, the thing I like most about Sketchup is that it lets me see the potential conflicts in the design, and plan around them or adapt the parts to fit like they should. It's a great tool for visualizing the end product, too.
The biggest problem I have is that, no matter how much design experience I have, my shops skills and shop tools aren't quite up to the production standard I want to hit; I have a tough time making the parts to print. It's a really good challenge.
All through this chassis-building phase, I've had this half-smile on my face. I like cranking new stuff out. And I like knowing I've gone way beyond necessity on material thickness and the number of fasteners holding it together. I tend to make stuff over-strong and combat ready.