EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: djacobow on February 06, 2014, 06:29:19 pm
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OK, folks, what is the state-of-the-art in getting your one-off project in a box, neatly, quickly, painlessly, inexpensively?
I'm having lots of fun hacking up all sorts of projects but I notice I spend inordinate less fun time trying to wrap up projects into permanent enclosures. And in the end, they suck. The best I can figure out is to use cheap ABS boxes and cut openings in them, usually with a utility knife. (And there is ALWAYS at least one knife slip.)
Because PCB holes never match those in the cheapie boxes (if they have them at all) to mount PCBs, I've been resorting to hot-gluing small pieces of furring strips to the bottom of the box and screwing down the PCB with wood screws.
It ain't pretty on the outside OR the inside.
Looking forward to hearing what people do to make stuff that passes the Spousal Acceptance Test. If you are a master wood-worker or other skilled artisan, your ideas may be interesting, but I suspect less useful to this run-of-the mill hacker without a nice shop.
Regards,
David
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Unless one is good with wood or metal, I'd say 3d printing... Also a nibbler goes a long way in doing front panel cutouts.
Or, alternatively, do what the pros do: get the box first, then design the PCB to fit it, with mounting holes in the right places.
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i have had the problem as i have been designing a psu proper instrument enclosures are realy expensive i ended up buying a nice £10 from maplin and now its too small. its hard to design a product around the enclosure as the design is alwase changing especialy when using vero board or strip board.
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Yes, even with PCBs, some of us, ahem, might take a few trips around the block to get it exactly right, and the size might change a few times.
Also, frankly, I design my PCBs to be as small as possible to save money!
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A Dremel tool with a lot of attachments makes an imprecise substitute for an end mill. It can cut odd freeform shapes reasonably well.
A nibbler tool is great for straight or square holes.
A step drill is very useful for round holes.
If you're working in sheet metal, a hand reamer can gently fine-tune the size of round holes. In particular, Altoids mint tins and similar flimsy metal cases can be destroyed with a medium to large sized drill bit, but by drilling a small hole and reaming it out by hand, you can get a nice round hole without tearing or bending the nearby metal.
But yeah, it's always a problem to package things up for one-off projects. I wish someone made a system of project boxes with exactly matching sizes of protoboard that would easily and neatly mount inside. If it came with some sort of modular system for mounting jacks and switches (like an extension of the keystone system http://en.wikipedia.org/wiki/Keystone_module (http://en.wikipedia.org/wiki/Keystone_module) ), I think it would be a winner.
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AG6QR,
Thanks for those ideas! I have a dremel tool but have not had much luck with it and plastic -- the plastic melts; it gets ugly. Maybe I need to go for the metal boxes. I like plastic because it's easier to work and some of my projects have AC mains power and I like the insulation, but I guess I could just ground a metal box.
I'm going to get a reamer on your recommendation. Just last night I was widening a hole using all manner of inappropriate tools. The size required -- for a pushbutton -- was between drill bit sizes I had.
I like your idea of a project box "system" with standard holes, punchouts, etc, with room for standard size vero boards and other normal connectors (16x2 LCD, ethernet, USB, power, 1/8" audio, yadda yadda)
PS -- question on the nibbler: though the nibbles they take out are relatively small, the head of the tool seems quite big. Can this be used to make a square hole the size of and Ethernet jack or similar? I usually drill a hole and expand it with a knife; I can't quite see how you get a nibble in there. On the other hand, it probably would work well for LCD openings and other larger holes.
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There are several different tools that go by the name nibbler and they have quite different functions and operation. The nibbler that RadioShack sells (sold? They seem to have closed them out) has a square head that takes a bite of about 1/16" x 1/4" when the handle is squeezed and the head pulled against a die.
Hmmm....Digikey appears to have them in stock for $13.
One of the other kinds of nibblers is designed to cut apart sheet metal. These are not so useful.
Regarding a reamer...in a pinch, one blade of a large pair of scissors will work well.
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Yes, Jon has a picture of the type of nibbler I use. It is capable of nibbling out a hole for something like an ethernet jack. You have to drill a starter hole, or sometimes you can start working at the seam of a box.
And for completeness sake, there are quit a few tools that go by the name "reamer". The hand reamer I use for enlarging round holes in mint tins looks like this one (from wikipedia).
http://en.wikipedia.org/wiki/File:Taper_reamer_K-442.jpg (http://en.wikipedia.org/wiki/File:Taper_reamer_K-442.jpg)
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I see. Only the moving part of the tool needs to poke through the hole. Got it now!
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OK, folks, what is the state-of-the-art in getting your one-off project in a box, neatly, quickly, painlessly, inexpensively?
you have to start from the box. i've just been repeating this to myself recently :-+ i know your pain. my father told me, they were enclosing electronics into a box for carrying soap, didn't try it yet, but sounds reasonable.
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Those boxes made with interlocking U-shaped pieces are the absolute worst to put something in if you need anything more than simple round holes. The shapes are awkward and it's hard to get the end panels to lay flat so you can work on them. Clam shell types with separate flat pieces for the front and rear panels are much better.
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Depending on a project of course, but I find laser cut cases work quite nicely and look very decent.
Here is one I did for example:
(https://dl.dropboxusercontent.com/u/2414406/Photo%202-7-2014%2C%206%2025%2034%20PM.jpg)
OK, folks, what is the state-of-the-art in getting your one-off project in a box, neatly, quickly, painlessly, inexpensively?
I'm having lots of fun hacking up all sorts of projects but I notice I spend inordinate less fun time trying to wrap up projects into permanent enclosures. And in the end, they suck. The best I can figure out is to use cheap ABS boxes and cut openings in them, usually with a utility knife. (And there is ALWAYS at least one knife slip.)
Because PCB holes never match those in the cheapie boxes (if they have them at all) to mount PCBs, I've been resorting to hot-gluing small pieces of furring strips to the bottom of the box and screwing down the PCB with wood screws.
It ain't pretty on the outside OR the inside.
Looking forward to hearing what people do to make stuff that passes the Spousal Acceptance Test. If you are a master wood-worker or other skilled artisan, your ideas may be interesting, but I suspect less useful to this run-of-the mill hacker without a nice shop.
Regards,
David
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I also recommend selecting the box first, before you get your PCB made, and design the PCB to fit the box.
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For doing one off cases at work i use a proper drill press and good drills in the right size. After drilling comes filing. You need some good but small files for metalwork. Larger Breakouts are drilled first, then roughly cut to shape with a dremel and the rest is - filing.
Holes for Buttons and stuff that you have the right drill bit for:
- Mark exactly where to place it (I always prefer a scriber for all markings related to mechanical work).
- Hit the center with a center punch to give the drill bit some guidance. This way it won't wander around on the surface.
- Use some clamping if you work with metal or small parts, don't wear gloves when working with rotating tools (danger of getting sucked in). For larger Plastic parts and very small drill sizes this can be skipped, but I do not recommend that! Clamping is not only for safety: it makes sure your drill goes down exactly where you want it because the workpiece cannot wander away. Of course it takes more time to align the piece exactly and clamp it down at that very position precisely. But it is worth your time if you care for the looks! Larger drills need smaller speeds, little drills are allowed to turn faster. (10mm about 600 to 800 RPM, 4mm about 1200 RPM as rule of thump). It takes some practice, but you will hear and feel if the speed or pressure is wrong: The drill starts to rattle, it sounds wrong, the material behaves somehow unexpected - you get it with practice. Too slow turning drills won't do good, too: They tend to get caught and then can possibly break or give a bad looking hole.
- deburr with a countersink (I prefer a handheld one, but it can be done with the drillpress in the same clamping position. Danger with doing so is to leave a very deep groove as I find it hard to get the height right. By hand you have better control.
Larger Holes for Buttons and stuff bigger than your maximum drill bit size:
This happens often with connectors and stuff. Most simple drill presses can only take drill bits up to 10 or 12mm in diameter. You need a hole cutter (https://www.eevblog.com/forum/beginners/boxes!/?action=dlattach;attach=80439;image) for that. I would only recommend them for plastics and possibly aluminium, but never for steel! For steel and also aluminium I prefer these screw piercers: (https://www.eevblog.com/forum/beginners/boxes!/?action=dlattach;attach=80441;image)
The rest is the same as before:
- Mark exactly and drill as stated before in the exact size your next tool needs: This meens in the screws diameter for the piercer or in the first step of the hole cutter. This hole does not need to be deburred.
- the hole cutter is used as a normal drill but with very slow speeds. Take care, and clamp everything down very well!
- The piercer is simply placed and the screw turned until the material breaks and it comes loose again. Take care, you can ruin them with very thin metal sheets wich can bend and get stuck in there. You sometimes cannot get them out then without destroying the hole tool or at least the screw.
- You won't have a Countersink for these holes. Use a proper deburring tool if you have one or a knive with a small blade or needle files.
small rectangular Holes
-Mark where you need the breakout. Do this VERY precisely again.
-Take your smallest drill, maximum 3mm. If the Item to be placed has a bit of a frame covering a bit of your mess you are lucky. Punch some guidance right onto all the corners of the breakout and drill as stated above. If there is no frame step back from the corners: 1/2 Diameter of your drill PLUS some extra 0.5mm for safety. Punch and drill.
- The inner of the breakout is then be drilled out, too. If you have a bit big enough choose as follows: smallest diameter of your breakout MINUS 1mm or better 2mm for beginners. Mark a center line, punch some guidance holes and drill. remember to stay a bit away from the sides to not ruin it! You can overlap the holes a bit, but don't overlap too much or your drill will get caught again and make a big mess.
- Grab your files and start filing. First every file that fits is ok to smooth out the holes. Then when you begin to get to the desired sides of the breakout a larger flat file helps a lot to give an even surface. Note that usually one small side of the flat file has teeth, too, and the other has not. Make use of this fact to get right into the corners.
Larger rectangular cutouts
- mark again and do the corner holes as before.
- Option one: Take out the inner with a large drill as before. It takes more holes but works well. File down and you're done.
- Option two: If the breakout is really large you can take a Dremel like tool and start to work right on the desired edges. But this is very likely to make a mess if you don't have some practice. With plastics, take down the speed as low as possible! Don't give any pressure, the blade will cut its way. Else it will melt the workpiece. You may also try a nibbler as stated by others. Or a fret saw! That is a very precise tool. Can be used for small rectangular breakouts, too. Nearly nobody knows, but you can get metal cutting blades for these and they work a treat! Cheap too.
- Large breakouts in plastics I deburr with a cutter. Else I choose fine files or a deburring tool.
cutouts for Alignment pins
- Drill the hole for the nominal diameter of the piece as stated above, NOT larger!
- Take a needle file and grind your way in by hand to make room for the pin(s).
Sounds like lots of efforts for a simple box? IT IS! But a nice box requieres at least the same and exact work as a good PCB and design. If it is skipped it will end in a mess.
Some general ideas for homeuse and cheaper working:
- if you don't have the workshop and room to do it, stick to plastics. You can even get metal cases with plastic fronts and backs. Plastic is easier to work with and the tools are cheaper in general. If you don't have a drill press you may even be able to get it right with an electric screwdriver.
- choose boxes with flat sheets of material to work on if you don't have the possibility of proper underfeeding and clamping. Parts in U-shape or L-shape are often hard to handle.
- have lots of scrapwood lying around your drillpress. This helps a lot when underfeeding, to clamp down without scratching the surface and so on.
- thin sheets of material can be supported with a flat piece of wood or plastic when drilling. Place it underneath and drill through your workpiece into that scrapwood. No warping!
- it is ok to choose the box after your design is finished. Actually I like to do it that way! You know exactly how much room you need inside. Also you know what elements you have on the outside. Choose a fitting box, then step back and go one size larger, if you don't have practice two sizes larger or even more. Trust me, you will need that room! Inside is less space, there are always some parts in there that get in the way, your external hardware reaches into the case a good bit... you get it. When arranging frontplates remember to leave room for some print, even if you don't actually print on there you will most likely want to write down some labels on there later. For one-off projects labels can be done with a labelprinter. These are cheap and work well. Labels on clear foil don't stick out too much but white foil gives always the right background to easily read the writing. It looks cleaner and more professional than written by hand. Just make sure to degrease before applying the labels and to align them very well. The Eye catches every mess there very well.
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Forget UL, CSA, CE, TUV.
By far the most stringent test in the industry is the SAT (Spousal Acceptance Test).
It has been the bane of many a hobbyist.
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Forget UL, CSA, CE, TUV.
By far the most stringent test in the industry is the SAT (Spousal Acceptance Test).
It has been the bane of many a hobbyist.
The SAT is usually a fail for me when I build projects for myself. I am more function over form and SWMBO is more form over function. I will admit, she did give me props for the workbench and the o-scope cart I made.