Surface Mount Stencils

I’ve been working on a project recently that calls for a pretty sizable board, with a fair number of parts on it (4″ x 10″ board size).

Traditionally when I’ve assembled these boards, I’ve either used wire solder and soldered parts on by hand, or more recently, been using a syringe with solder paste, placing all the parts on, and then placing the board in a toaster oven to reflow all the parts at once.

For a board this large though, either prospect was going to be pretty tedious, on top of placing the components to begin with, so I decided that I was going to try using a solder paste stencil this time.

A stencil is simply a sheet, usually of stainless steel or mylar plastic, with precisely cut holes in it where you want the solder paste to go. You squeegee the paste over the top, and it deposits just the right amount, right where you need it.

I got this stencil from OSH Stencils, and it was pretty inexpensive considering again that this is a large board.

The critical thing about it is getting it lined up properly with the board itself. Laying down just the right amount of paste in the wrong spot doesn’t help any, so the pcb, some framing supports, and the stencil were all taped down to prevent any movement.

After placing all the parts and reflowing, I had a perfectly soldered board.

The through hole parts still have to be soldered on manually though. No wave soldering for me yet…

Posted in Electronics, Projects | Leave a comment

Chain Mail Experiment

Medieval armor is an interesting subject, and while I don’t have much interest in acquiring any or joining in for any re-enactments, I was curious about how it is made, and what it behaves like.

With a bit of scrap galvanized wire I had laying around, I took a bit of time one evening to wrap it into a spring on my lathe, cut it into rings, and then form the rings into a small chunk of chain mail.

I’m pretty pleased with the results. It’s a neat bit of material that came out, albeit very time consuming to produce.

Posted in Art, Random | Leave a comment

Propane Burner

While charcoal and a blower works OK for the aluminum melting projects I’ve been doing, I was getting frustrated with the mess, hassle, and cost of that setup. The charcoal created ashes that sometimes got into the aluminum and needed to be cleaned up in general, there were a lot more parts involved to get a working setup, and it had to be constantly fed new charcoal, and while charcoal isn’t terribly expensive, a propane torch would get a few melts out of a barbecue sized propane tank, and make the process cheaper.

So, using this video as a reference, I made my own torch and gave it a test. Additionally my sister and brother-in-law gave me a new graphite crucible, which has also greatly improved the melting process.

I had a whole bunch of cans saved up, mostly from folks who have saved cans for me and brought them over. I had somewhere around four garbage bags full of cans to melt down. The propane burner and graphite crucible handled them with ease!

In all, I melted down around 315 cans, and ended up with just over 6 pounds (~2.7kg) of aluminum cast into heart shaped ingots.

Posted in Projects | Leave a comment

Fire Piston

I’ve really been enjoying watching Clickspring’s videos recently, and it encouraged me to make one of his projects as a christmas gift for my father. As someone who’s into the outdoors, I thought a fire piston would be the perfect choice.

I had some aluminum round stock laying around in my (albeit small) scrap pile, and spent a few hours on the lathe shaping it into a functioning fire piston.

The fire piston is a really simple device, which uses a rod shoved into a cylinder sealed with O-rings, to suddenly compress the air inside, which will heat it up enough to ignite some material. Char cloth is commonly used.

The char cloth provides a burning ember that you can apply to your tinder and start a fire.

No matches, just the laws of physics!

Posted in Projects | Leave a comment

Testing Self Clinching Standoffs

I’ve recently been looking at better ways to mount a PCB inside a metal enclosure. Primarily I’m interested in ways that don’t require screws protruding from the bottom.

I found these self clinching standoffs on Fastenal’s web site, and figured I’d give them a try. Normally they’re installed using an automated press, but I gave it a shot with the cheap Harbor Freight press I’ve got.

Apologies for the vertical format video. Handling the camera, the metal, and the press at the same time was a bit unwieldy.

Posted in Random | Leave a comment