When I have completed a prototype board, I often want to use it to: extend the prototype, integrate the prototype with other prototypes, protect the prototype or even show the prototype board off.
I don't want to mount the prototype board in a project box because that usually means poking around in a confined space to jiggle wires, connect other things to it, etc.
Sometimes, I also need my prototype board to be a little bit heavier so that when I connect a battery or another component to it, it doesn't shift or twist around.
That's when I go for a simple acrylic sheet that I can mount my board on.
If you drill some more holes into the acrylic mounting board, you can then mount your circuit on the wall, ceiling, etc.
This instructable is about how I go about mounting my prototype circuits to an acrylic board.
Step 1: Materials
For this instructable, I'm using:
- 4 x M3 15mm bolts (I buy them in packets of 200 from Jaycar, but you can get them at hardware stores too);
- 4 x 12mm threaded nylon standoff nuts (Jaycar, eBay, etc.);
- 3mm thick clear acrylic sheet (I bought a 1000mm x 600mm sheet from the hardware store for about $25);
- 4 x rubber "feet" (I bought some General Use Surface Savers/Bumpers from the hardware section of the supermarket);
- The circuit that you want to mount.
You will also need:
- craft knife;
- jigsaw (optional);
- circular saw (optional);
- Sandpaper (coarse to very fine);
Step 2: How to Do It
I start with my circuit board. The best time to make your mounting board is when you are making your circuit ... before it's populated. Lay the drilled circuit board over the acrylic sheet and mark the outline and where the mounting holes should go. I usually try to make 4 mounting holes so that my board is stable, but sometimes 2 or 3 holes is all that you have room for.
Acrylic is usually sold with a protective plastic sheet on both sides, it is important to leave this on until you have completed the cutting and sanding of your edges. The plastic sheet will protect the acrylic from being scratched by tools while you are cutting/sanding it.
Cutting acrylic is not too difficult but care is needed. If you are using a circular saw or a jigsaw, slow and steady is the key. Too fast and the acrylic will chip, go too slowly and the waste will melt with the heat generated by the friction of the blade (not too hard to clean up, though a pain).You can also use a hacksaw with a fine tooth blade on it. I've also used the score and snap method, that is, score both sides of the acrylic with a craft knife (using a straight-edge like a metal ruler) and then place the acrylic over a sharp edge on the line of your cut, bend the acrylic and it will snap along the score.
However you cut the acrylic, I recommend trying it first before you commit to a final board. Also, the edge is likely to be rough ... a coarse sandpaper can be used to trim the acrylic, and then a finer sandpaper to make it clean and shiny. You can go down to a wet paper for a really glossy finish, if that's what you're into ;)
Using a 3mm drill bit, drill the holes for the bolts. You want to make the holes in your acrylic a tight fit so that when you screw the bolts in, they will cut their own thread into the acrylic. Again, I counsel you to try on a waste piece before committing to the final drill bit size.
After you have cut and drilled your acrylic mounting board, go a head and peel the protective plastic from the top and bottom of the acrylic.
Wash the piece in some cold to warm water to clean off all of the dust and chips from the board and give it a good dry with a towel.
Place the bolts through the mounting holes of your circuit board and loosely fasten the nylon stand-off nuts. Offer the circuit board to the acrylic sheet to make sure that you have the correct orientation (I've done this too many times to imagine that I'd get it oriented correctly the first time). If you've spun you board around twice and it still isn't fitting ... don't forget that you can also turn the acrylic sheet over and try again!
With the bolts sitting in the mounting holes, screw then firmly in place. The bolts will score their own threads into the acrylic, so, if you take it all apart, next time the bolts will go in easily.
Now that the circuit is attached to the acrylic sheet ... place the self-adhesive rubber feet onto the bottom of the board. The rubber feet are very handy for two practical reasons:
- The board won't slip around when you are working with it; and
- It raises the board off your work surface, preventing scratching.
That's it ... you are done. Sit back and admire your work.
Step 3: Space ... the Final Frontier
Eurgh, now I really feel like a nerd.
The stand-off nuts give you 12mm between the circuit board and the acrylic sheet. There are a couple of reasons why I want space between the bottom of my circuit and the acrylic sheet.
If my circuit generates heat, then I don't want to melt the acrylic. Also, the gap allows air to circulate under my board to help dissipate some of that heat.
(If) my work surface is messy (it often is) then I don't want random bits of wire or the legs of components to "interact" with my copper traces and cause me some unexpected faults.
From an aesthetic perspective ... I like to have my circuit boards raised. It looks more like I've actually thought about what I'm doing and adds to the overall appeal of the board.
By all means use a shorter stand-off and shorter bolts, or even use a different type of stand-off, I'm not prescribing a standard that you should adhere to.
Step 4: What Next?
When my circuits are approaching final use or I'm actually going to do something with the circuit, I've made some acrylic enclosures by building sides (and tops) for the single plane acrylic mounting boards.
The clear acrylic, in this case, is good because otherwise the LED wouldn't be visible ... also, I want to be able to show off the bottom of the circuit too.
Of course, you may want to use another colour or opacity of acrylic sheet. Fortunately, it comes in so MANY different colours, opacity, texture, thickness ... the world is your shallow water marine bivalve.
If you look closely to the enclosure above, you will see that my early work in this area was ... well, to be blunt ... rubbish. Still, the enclosure does what I want it to do and my rework later is much improved.
The acrylic mounting board is very useful for mounting more than one circuit board. For instance, I have a mounting board that has 2 Arduino (UNO and Freetronics) an ATTiny84 and ATTiny85 prototyping board and a power supply. It makes a handy electronics bench tool, although, I prefer the single module style.