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Rolling Your Own

As an engineer and a hobbyist, I build lots of stuff. Often, when stuffing a PC board with through-hole parts, I'd clamp the board in a special vice meant for just that purpose. I'd load the parts in and start soldering.

If the special vice were not available, I would not hesitate to put something together using alligator clips, vice grips, some #12AWG bus wire, and a block of scrap steel for weight. It didn't look pretty, but it got the job done (which I think is one definition of engineering; another one being like science, but louder).

One time, I was winding up some of my own guitar pickups, and I needed some sort of cover to put over the top, purely for esthetic reasons. To fabricate something out of lightweight cardstock (like a 3×5 card), I built a wooden fixture/jig around which I wrapped the cardstock to get the right shape.

I carefully glued the wrap portion. Then I glued on a top piece, did some minor trimming, and spray painted it all flat black. It's not bad, if I do say so myself.

For putting together mechanical assemblies, I often build specialty tools to go with the jigs. These take various forms — perhaps a screwdriver with a ground-down blade to fit in a tight spot; or a drill bit with the end ground flat, so it's more like a mill; or a piece of music wire (a guitar string, actually) bent into an odd shape to help fish some cable through a tight spot.

I've brazed up special socket wrench fittings for car wheel assemblies. I've used them only a few times, but it was well worth the effort. And I've made special Allen keys for various jobs.

Or how about a bottle washer/sprayer made from pipe fittings to help rinse out the ketchup bottles before recycling? It fits on to the sprayer on the kitchen sink, and it shoots the water in with plenty of room for it to run back out.

And that bit of plumbing reminds me — you can build no small amount of fixturing from rigid PVC pipe (the white stuff). Your favorite hardware store carries not only elbows, couplings, and tees, but probably 3D-tees.

And saddle-tees.

One of my favorites is this test board that looks more like a dog's dinner (as my coworker Max Maxfield likes to describe things — or possibly my blogs).

This again relates to some guitar circuitry I was assembling. Again, it's not pretty, but it's quite functional. What kind of fixturing do you build yourself to make your work easier?

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10 comments on “Rolling Your Own

  1. Davidled
    July 2, 2013

    Some guitar circuitry is very much impressive as circuit is working properly without any short circuit.  Recently, we bought two guitars for my son and daughter. I might consider the design of preamp for their guitars as using old fashion of PCB design. I hope that my family has no complain for my design. But, it will be exciting for engineering education.

  2. eafpres
    July 2, 2013

    Most of the fixtures I've used for soldering small stuff involved some kind of base with adjustable position and some small clamps, especially alligator clips used as small spring loaded grippers.  Here is a photo of the general class of thing I've used and seen:

    Handy Work Station

    Back in my production days, we had an RF assembly that was part of an active antenna module for cars (i.e., it was one of those black fin modules you see on cars everywhere now).  The circuit board was assembled mainly by SMT, but typically there were two ceramically loaded patch antennas added whose feed pin had to be hand soldered, and 2 or 3 coaxial cables that had to be hand soldered.  These were all issues in production.

    For the coaxial cables, we had aluminum fixtures where the board was inserted, then a hinged cover came down with a slot to align the cable and an opening where soldering was to occur.  There was some kind of spring clamp that held the cable once the operator placed it.  Cables arrived to the station pre-tinned.

    This whole setup made it easier for the operators to solder well without damaging other areas.  Once fixtured, they would insert the tip of the (digitally controlled) soldering iron, then feed wire solder to get a fillet, then remove the iron.  Worked pretty well; one factory I was involved in did about 10M coax to PCB solder joints a year this way and the total end of line reject rate was < 10 ppm.

  3. Brad Albing
    July 2, 2013

    Not bad – especially for working with coax which is typically prone to melting and shorting when being soldered.

  4. RedDerek
    July 3, 2013

    The company I do much work for now is a machine shop with 3-d mills, lathes, water jet, etc. Quite nice to have access to. Some of things I have had built…

    1. Took that chunk of granite that was cut out for the cook-top was water jetted into smaller pieces that are assembled as a puzzle. Lighter segements for small trivets on the table. Or assemble up as a jigsaw puzzle for a larger one.

    2. Adjusting the small trim pots with a flat screw driver is difficult as the screwdriver tends to slip off frequently. I had one jewlers screwdriver modified to have a small barrell added to it. The barrell fits over the screw and thus keeps the screwdriver tip in the slot.

    3. I had many screw hooks to put in the eves around the house to hold Christmas lights – easy to put up and pull down. I had a custom tool made that I can fit into a battery powered drill. Clip in the hook, let the drill do all the work. Cut the time down to installing a hook from a minute to seconds.

  5. Vishal Prajapati
    July 4, 2013

    Derek I like the screw driver with berrel idea. It is nice to have tools custom built for our own use with samllest change in it. I generally use plastic boxes that generally come with the packaging of sample ICs to hold the resistors of different values.

  6. antedeluvian2
    July 4, 2013

    RedDerek

    2. Adjusting the small trim pots with a flat screw driver is difficult as the screwdriver tends to slip off frequently. I had one jewlers screwdriver modified to have a small barrell added to it. The barrell fits over the screw and thus keeps the screwdriver tip in the slot.

    These are commercially available. Take a look at this page, bottom right hand corner.

    I also have one from Bourns. Look at the H-90 on page 165 of their catalog.

    The problem with both is that one side has an exposed blade and I find it cuts into the skin if you have a number of adjustments to make.

  7. RedDerek
    July 4, 2013

    I actually have a jeweler's screwdriver and the barrel is long. The original intent of the tool was to reach down into an old box of electronics (I was doing repair), and unscrew some connectors that had a similar shape for the screw. The regular screwdriver kept falling off. The tool is all metal and will not wear out easily. I can post a picture, but the Bourns is the concept – did not know that was around many years ago. Besides, with a machine shop at your call it sometimes is faster to ask someone to whip one up in 30 minutes or less.

  8. antedeluvian2
    July 4, 2013

    RedDerek

    There are screwdrivers that will hold the screw on and up here in Canada we have the robertson screw that is designed so that it won't fall off. There was a discussion recently that covered this topic (screwdrivers) and other tools on the Connecting Edge. Rather than re-hash the topic here is one blog and here is the other.

  9. Brad Albing
    July 6, 2013

    @DaeJ – Guitar preamps are pretty easy to design  – there are lots of schematics published showing many ways to do what you need. Let us know what you end up with.

  10. Brad Albing
    July 6, 2013

    @Derek – I've done that same trick for your #3 for screw-eye installation.

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