Discreet Transistor Keyer Part 4 - Building the "scrap metal" enclosure.

In my last post, I mentioned Master Homebrewer Pete, N6QW's recent blog showing how he builds beautiful enclosures using an inexpensive bending brake.  Pete, a true craftsman, did a marvelous job, as any craftsman who takes pride in his work would.

Now, I'm going to show you the other side - how to quickly bend up a simple enclosure from a piece of scrap 22 ga. aluminum.  Because for some projects, simply being good enough is good enough!

I started with a couple of scrap "rails" that I had left over from another project and the keyer's circuit board:

Laying the bits on the bench, I took a couple of measurements and determined that the box would be about 4 1/2 inches square by 1 1/2 inches high.  The easiest enclosure to make (in my opinion) is the simple "clam shell", where you have  top and bottom panels that slip over one another to form a box.  Since I already had the rails for the front and rear, this one will be easy because I only need two bends in each panel. 

For the bottom, I laid out the dimensions on the scrap aluminum sheet.  Since the dimensions are 4 1/2" square and I'll need about a 1/2" "lip" on the left and right sides, I cut the piece to 4 1/2 x 5 1/2" using a pair of shears.

In the last picture, you can see the lines drawn on the soon-to-be bottom panel that show where the bends will be, um, bent.  Now, it's off the the "back room" to do the bending!

Lined up and clamped in the brake.  For a small bit like this, a single vise-grip is enough to hold it in place.  I use multiple C-clamps when working with larger pieces.

One side bent - square bend in seconds, try doing that the way the old handbooks tell you to. 

And repeat for the other side...

Nice!

 

 

The top is formed the same way, except that I left a full-height (1 1/2") "overhang" on each side instead of the 1/2" used on the bottom panel.

The components, ready for assembly.

When I'm in the mood, I've got a jig that I made to drill mounting holes in the corner of PCB with some degree of precision.  This isn't one of those times, so I laid the board where I wanted it to go, drilled the hole for one corner and fastened it with a screw and nut.

The single screw/nut hold the board in place while I drill the other three, and then all four corners get fastened.

Next, I fastened the front and rear panels to the bottom with pop-rivets.  Unfortunately, I didn't capture the excitement photographically, but trust me, it happened.

Now for the only "exotic" piece of hardware in this entire project: Rivnuts! 

Fastening the top of the enclosure to the box means that I'm not going to be able to use screws with nuts, and if I use rivets, then I'll invariably have to drill them out to fix something.  I could use sheet-metal screws, but they eventually get sloppy after being undone-redone a few times.  Rivnuts are cool; they're threaded inserts that attach like a rivet - the tool looks like a pop-rivet tool that, rather than having a hole for the rivet "lead", has a threaded stud.  Installation is a snap - drill the hole (for #6-32 inserts, drill a 9/16" hole), screw the Rivnut onto the tool, insert, squeeze the handle and bingo!

And that's it.  The finished product is certainly "good enough"; with a little body-work (filing the edges smooth and massaging out any dents) and paint, nobody will know that it was whipped together in about 45 minutes from a piece of scrap.

73!