The "other" part of an electronic project?

Discussion in 'The Projects Forum' started by RayInMS, Feb 3, 2014.

  1. RayInMS

    Thread Starter Member

    Dec 12, 2012
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    1
    I'm wrapping up yet another project, and I got to thinking...the AAC forum is an oasis of knowledge on all things electronic...but what about the other parts of a project?

    Project boxes/enclosures, perfboard vs. PC boards, standoffs, power options, mounting switches/knobs/LEDs...what about all of these little extra things that go into a project?

    Anybody got any tips or tricks they'd be willing to share? I'm particularly interested in any panel-related ideas, such as design, lettering, drilling, etc.

    Thanks!

    Ray
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Personally I favour building my own supplies, using a toroid transformer usually, because of the flexibility.
    If you want snazzy professional looking panels for a reasonable price, find a local engraver that does reverse engraved lamacoid, multi-colour is possible this way.
    You can even include your own logo if you want!
    The guy I use, I just email him a DWG Cad drawing.
    Max.
     
  3. #12

    Expert

    Nov 30, 2010
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    As I said to one friend, "If you're going to do electronics, you are suddenly going to discover you're also a sheet metal worker". Or, "It takes more time to address the ends of the wires than it takes to assemble the circuit board".

    Pre-fab boxes are a lot cheaper than having one made by a local sheet metal shop. To make a square hole, you pencil in the shape you want, fill it with as many round holes as you can get into the outline, and finish the job with a file. Aluminum is a lot easier to work with than steel. Plastic can be even easier, but I have sheet metal laying around because my day job is air conditioning. Besides, metal bends. Plastic generally doesn't bend unless you are good at heating it correctly. Besides, plastic fractures when you drop it. Metal usually doesn't fracture. A round hole can be used for the side tab on a potentiometer (to keep it from spinning when it shouldn't). You can buy blue Loctite to keep things from unscrewing. The red version is too strong. You'll never get it apart. Be sure to use a bench vise or clamps on your drill press. When the drill hangs, it can spin the sheet metal and slice you up real bad. Notice that I said, "when", not, "if". Drill your material between two blocks of scrap wood. It keeps the backside blowout to a minimum.
     
  4. MrChips

    Moderator

    Oct 2, 2009
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    What's on your mind. Fire away.
    I work with wood, plastic, acrylic, sheet metal, etc.

    One of my favorite vices is to collect the cases of discarded PCs and turn them into project boxes. Steel is not nice to work with. If you can find sheet aluminum that is easier. Right now I am working with extruded aluminum channel. My rule is keep it simple.

    See my DSP project here.
     
  5. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    The hardest part is being able to visualize the layout, the size, what size box it will fit in, etc. The art is in creating and making it come together.

    I use a drawing program to create the panel graphics, print it on white paper then apply it. I either use double sides tape or an overlay of crystal clear 2" wide tape.

    See attached the image of a VU meter I built for processing audio tracks that has both an analog meter and LED string meter. The face of the analog meter was created by me, printed, cut out and applied to the meter face with double stick tape. The box face graphics are printed on white paper and attached with clear tape overlay.

    The LEDs are edge mounted to the PCB inside with the driver and amps on board. The circuitry driving the analog meter is on a small PCB that mounts inside to the two screws on the meter that make the electrical connection.

    I had to take the meter apart and put on a "reference grid" to get location points for the calibration and dB level markers then later applied the final meter face.
     
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  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The sheet metal references reminds me, if you are going to be doing a few panel etc, you may find it useful to pick up a hole punch set such as made by Greenlee, they have many forms for punch shapes available, as well as the standard hole punches.
    They make a nice clean job.
    Max.
     
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  7. burger2227

    Member

    Feb 3, 2014
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    Hi all! New member!

    Women use all kinds of boxes for jewelry and stuff. I found a clear plastic box with all kinds of internal compartments that could be cut out if need be for beads at Walmart that only cost a dollar. In fact, the box could hold TWO projects as it has a front and back door. Compartments could hold an array of batteries.

    I plan to use it as a tester box for transistors and other things. If you are not proud of your solder work, just paint the box!

    Ted
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Another source for some sturdy boxes for shop projects is the Dollar Store.
    Max.
     
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  9. RichardO

    Well-Known Member

    May 4, 2013
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    ... but first use a nibbling tool. (I have two of them. One of my best tool investments.)
     
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  10. #12

    Expert

    Nov 30, 2010
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    PS, the fact that the parts will fit in the box doesn't mean they should. I have made boxes that got way too hot, more than once.
     
  11. inwo

    Well-Known Member

    Nov 7, 2013
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    If we have any inventor/machinist on here.

    I tried and it's over my pay grade.

    There are hand nibblers available now. Puny useless pieces of useless crap. Did I say useless?

    They nibble a very tiny piece from 22 or 18 gauge max.

    I'm thinking nibbling 1/8" each cut, 1/4" curf in 16 gauge.

    Seems I always need rectangle holes. Only square punch I have is 1" X 1".

    Picked up a notcher for oil-tight controls for a start, but never got anywhere.

    edit:
    Apologies to nibbler lovers.
     
  12. burger2227

    Member

    Feb 3, 2014
    190
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    I just fit a power failure circuit into a night light! It charges the battery too. Actually the chip is used as a Joule thief that also regulates charging and battery discharge.

    http://petesqbsite.com/phpBB3/viewt...2&sid=40ac7e6a6be354d0a60460b7b95d46ba#p22892

    The actual schematic is shown in a previous post in that thread. The green LED in schematic also serves as a permanently on night light that uses little power. It charges at 1.2 ma.

    The 5252F chip can light LED's with just a coil and battery. It could also be used to light up jewelry or the inside of a box. Let me know if you are interested in the chip. I found a supplier in China.
     
    Last edited: Feb 3, 2014
  13. burger2227

    Member

    Feb 3, 2014
    190
    24
    Try a Rockwell Sonicrafter. It vibrates a steel saw blade to cut through steel without any threat of injury as the vibrating blade needs a solid object clamped still. It won't even hurt a balloon!

    http://i301.photobucket.com/albums/nn53/burger2227/SonicraftPCB.jpg

    http://petesqbsite.com/phpBB3/viewtopic.php?f=4&t=3730&p=22880#p22880
     
    Last edited: Feb 3, 2014
  14. RayInMS

    Thread Starter Member

    Dec 12, 2012
    89
    1
    Good ideas so far, thanks guys.

    What hangs me up (almost every time) is drilling. I measure, re-measure, grid, cross-reference the grid with my measurements, and then drill. Small bits first, then larger bits to accommodate the size of the part. And the damn holes are still wonky. Even if they are off-axis only by an 1/16th of an inch it shows. I guess a drill press would fix this (that's my next purchase), but it gets OLD when you work so hard on a panel only to have three or four off-axis holes screw up the visual appeal of the whole thing.

    What about power connections? Do you guys prefer to panel-mount female jacks or just run wire (with strain relief, of course) through a grommet?
     
  15. MrChips

    Moderator

    Oct 2, 2009
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    Always use a center punch to put an indent at the desired center of the hole.
    The indent keeps the first (small) drill from wandering off from the center.
     
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  16. MrChips

    Moderator

    Oct 2, 2009
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    Either way. If I have room on a larger project I use AC sockets. Better still, use a socket with built-in Corcom RF filters.

    On a smaller box I use strain relief, no grommet.

    A point about AC connection needs mentioning. I see imported equipment wired incorrectly.

    In North America, the AC power cord is color coded:

    BLACK = LIVE
    WHITE = NEUTRAL
    GREEN = GROUND.

    The AC cord must be secured with a strain relief.
    The GROUND wire goes to a solder lug that is screwed to the metal chassis.
    The LIVE wire goes to the TIP of the fuse holder and covered with heat shrink. A connection goes from the body of the fuse holder to the power switch. The power switch is connected to one of wires of the primary of the transformer.

    The NEUTRAL wire connects to the other wire of the primary of the transformer.

    Remember to slip heat shrink tubing over the fuse and switch connections before soldering.
     
  17. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    For drilling a ROUND hole in sheet metal, you need to use a 'step drill'. Step drill is the generic name for a 'unibit', they were the first to market them. The real unibits are more expensive, but I have them and some off brand ones (Harbor Freight) and can't tell the difference in the hole quality. So unless your doing this for a living, I'd go with the off brand.

    Even with a drill press a twist drill will make a 'wonky' hole shape. And with the step drill it doesn't catch the metal and make it spin when your drilling.

    A good layout then a center punch to mark the actual location is also a must for a quality looking panel. If you try a step drill you will be amazed at the way the holes turn out.


    For square or rectangle holes, lay out the shape, mark the center and drill the biggest hole you can fit in the center of the shape. Then a square fill to take out the rest of the metal to the layout lines. On sheet metal, a finer tooth file works better than a coarse one. It really doesn't take much time, or a big investment in tools to do this kind of thing.
     
    Last edited: Feb 4, 2014
  18. shortbus

    AAC Fanatic!

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    strantor and mcgyvr like this.
  19. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    ^^^ cool press brake attachment for the vise.. never seen that before.
     
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  20. TANDBERGEREN

    Member

    Jan 20, 2014
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    I never use any rotatong tools for making holes bigger than 6-8mm.
    Good lowpriced punches do a far better job, and are quite easy to get accurate too.
    Clean cuts is also an advantage.
     
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