Instructables
Picture of Clear polycarbonate enclosures
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So about a year ago I decided that I wanted to get into AVR microcontrollers. After ordering an AVR pocket programmer from Sparkfun , I soon realized that it was too delicate to be sitting on a workbench full of wire clippings. I knew I needed a small enclosure to put it in, but couldn't find anything I really liked. My final decision was to make my own.

This instructable will explain the steps necessary to construct a "Lexan" shell for an arduino UNO (or other arduino). Of course these steps can be adapted to almost anything.

I don't remember where I learned this method, but it was definitely from another Instructable. Here are some with similar methods:

- http://www.instructables.com/id/LCD-Cover/

- http://www.instructables.com/id/CULTRIVOR-Custom-30-Knife-Block/

- http://www.instructables.com/id/Motorcycle-Hand-Wind-Deflectors-version-21/

 
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Step 1: Tools/Materials

Picture of Tools/Materials

Use whatever tools you like, these are what I used:
- Ruler/Square combo
- Table Saw
- Jig Saw
- Pencil torch
- Lathe
- Drill press
- Fine sandpaper
- Small file set
- Dremel

Materials:
- Lexan polycarbonate (1/10" thickness is usually carried by home improvement stores)
- Chunk of 2X4 wood
- Masking tape
- 4 nice screws with matching nuts (~18mm length)
- 2 - 1" Nylon spacers (must fit over screws)

Step 2: Make a bending jig

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This step is OPTIONAL but highly RECOMMENDED

This is where the table saw and chunk of 2X4 come in. I have tried to bend polycarbonate over the edge of a table and in a vise, its easier in the long run to make a jig.

If you don't have a scrap piece of wood laying around, go to your local home improvement store near the end of business hours and ask if they have any scrap they're throwing away. Home depot gladly gave me a few small pieces.

If you've never used a table saw before, this is not the time to start; have someone else cut it for you. The goal is to cut slots of varying depths into your scrap wood, be careful. To get an idea of the depth required for your project, take the distance from the edge of the Lexan to the target bend line and subtract 1/8". Why? Because when you eventually use a torch to heat the Lexan it almost always bends 1/8" above the wood. Also keep in mind that if you want a "U" shape, two bends need to be made. The slot will need to be close enough to the edge so that the first bend will clear the wood when making the second bend.

In my case I wanted the walls to be 5/8" high, subtract 1/8" and I need a 1/2" deep slot. (Close to the end of the wood)


Step 3: Measure and cut

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According to my measurements, my arduino is about 2-11/16" long by 2-1/8" wide. In the design I chose to go with, the bottom shell covers the sides with the 4 headers and the top shell covers the ends with power/USB and ICSP header.

Bottom- 3-1/2" X 2-15/16"
2-1/8" (width of arduino) + 5/8" (side 1) + 5/8" (side 2) + 1/8 (for luck) = 3-1/2"
2-11/16" (length of arduino) + 1/8" (the luck that is added to the top) + 1/8" (for sanding) = 2-15/16"

Top- 4-1/16" X 2-3/8"
2-11/16 (length of arduino) + 5/8 (end 1) + 5/8 (end 2) + 1/8 (for luck) = 4-1/16"
2-1/8" (width of arduino) + 1/8" (the luck that is added to the top) + 1/8" (for sanding) = 2-3/8"

You've probably heard the saying measure twice, cut once. Before picking up the jigsaw, cut out paper pieces the same size as your Lexan should be and bend them accordingly. Do the paper pieces fit together the way you expected them, will your Arduino fit inside? (excluding the USB and power connectors) If not, step back and decide what measurements need to be modified.

Be careful not to bend the wrong edges of the Lexan you cut, so labeling the bending edges is recommended.

You will inevitably end up with some scrap pieces, use them for test bends.

Step 4: Test bend(s)

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Its near impossible to bend Lexan perfectly the first time. So instead of overheating and possibly creating bubbles in your correctly cut Lexan, cut a few scrap pieces and practice your bending skills.

Reminder Lexan may give off toxic fumes when heated, just to be safe bend your Lexan in a well ventilated area.

- First, slide your Lexan piece into the slot in the wood; make sure it goes in all the way to the bottom.

- Next, take your torch and evenly heat the wood/Lexan corner while at the same time applying pressure in order to convince the Lexan to form in the right direction. Take your time, heat evenly across the bend and never stop moving the torch.

- When the Lexan starts to fold, push the folding piece all the way down to the wood and hold it down until it cools.

My test Lexan in the video ended up bubbling in one of the ends of the bend because it became too hot.




Step 5: Heat and bend

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Before you try to bend your perfectly cut pieces of Lexan, you may want to sand down the edges so they are flat and don't wabble in the jig. If the Lexan doesn't sit correctly in the jig, you may end up with a crooked bend.

By now you've heard the saying measure twice cut once, there is nothing more frustrating than realizing you've just bent the wrong piece the wrong way. So before you light your torch, use your cut out paper pieces and label the edges of the Lexan that need to be bent. Again do the paper pieces fit together the way you expected them? If not decide what bends need to be moved.

Its probably a good idea to do this in a well ventilated area.

Keep in mind that wider pieces of Lexan take more time to heat than thiner scrap pieces.
 
These are the bends that count, take your time, be patient and don't burn yourself. (or mess up :)

Step 6: Sand it down

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You can ignore this step if you were lucky enough to not have any excess Lexan in the way of your shell fitting together and looking nice.

The goal it to remove just enough Lexan so that the two halves slide together and don't have any "overhang". What I mean by "overhang" is Lexan that goes past the point where the two edges should intersect.

To accomplish this I started with a Dremel tool, then moved to rough sanding pads that I had laying around. To finish the edges I used some 400 grit sandpaper on a flat surface. The finer the sandpaper the longer it will take to remove material, but the better the edges will look.

Step 7: Drilling holes

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Hopefully by this step you were able to create a beautiful Lexan shell that almost fits an Arduino. In my case, I had to jump back to step 3 after severely mangling one of my bends.

Drilling holes may sound easy enough, but don't let it fool you; its tricky.

- First, find something to mark the Lexan with, it can be a pencil, pen or scribe. Take your arduino and set it in the bottom half of the Lexan shell. Center your arduino as best you can and apply pressure so it wont slide around. Holding your marking tool vertically, mark through the mounting holes in the Arduino to the Lexan below.

- Next, using a 1/16" drill bit , drill out undersized mounting holes in the bottom half of the base.

- Then, slide both halves of the shell together and secure them with tape. Orient the shell so that it is upside down and with the drill bit carefully go through the first set of holes in the bottom to drill the new holes in the top. If your using a hand drill, be very careful to keep it vertical. Finally remove the tape and re-drill all the holes with an 1/8" drill bit.

Don't forget the hole for the reset button. I used a 1/4" drill bit.

Step 8: More cutting and sanding

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The top half to the Lexan shell needs cut-outs for the USB connector, power connector and pin headers. This is more of a trial and error process. Don't let the picture throw you off, its the same piece of Lexan. I removed the plastic covering and replaced it with scotch tape because it was easier to write on. Don't use scotch tape unless you want to peel it off in small slivers, masking tape would have worked much better.

- First, estimate and mark the Lexan that needs to be removed for the power and USB connectors. Its always better to underestimate and have the connectors not fit rather than remove too much of the Lexan.

- Next, using a jigsaw roughly cut out the holes. Perfect the holes using a small file and sandpaper. I borrowed a small file set, if you cant find one a nail file would also work. Periodically check to make sure all the corners of the cut-out are at a 90 degree angles and the edges are straight.

- Finally, when the top half of the shell will fit over the arduino, repeat the process for the pin headers.

Step 9: Screws, nuts and spacers

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I had to visit the hardware store because I didn't like any of the screws I already had. I ended up purchasing 18 mm long chrome screws with matching nuts and two 1" long nylon spacers. If you are able to find the right size spacers it would save some time.

The bottom spacers need to be taller than the highest pin on the bottom of the arduino, on mine is about 3/32".

The top spacer need to fill the distance remaining from the top of the PCB to the top Lexan shell, when measuring make sure the spacers will fully support the Lexan and keep it from bending when the screws are tightened.

Cutting the nylon spacers can be simplified with a lathe and a razor blade. If you don't have access to a lathe you can mount the spacer in the chuck of a drill and again use a razor blade as it spins.

Step 10: Enjoy

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If you are unhappy with the quality of the edges of the Lexan, the pencil torch can be used to give the edges a "glazed" finish.

Congratulations, the next step is to enjoy your new custom enclosure. Shields will still fit on the arduino, just be careful of the screws on the top of the enclosure; they may short out pins on the bottom of some shields.

Of course this entire process would be simplified with a laser cutter, you can vote for this Instructable in the Epilog Challenge .


weish2 years ago
if you used counter-sunk bolts to hold your lexan enclosure together, you could reduce the risk of shorting pins on your shields. you could also give a thin coat of acrylic resin to fill and seal the bolt heads. you could still disassemble it by removing the nuts from the bottom, but you'd make your enclosure more functional
Jason-B (author)  weish2 years ago
I never even considered the shields when I was building this project, your absolutley right. It would probably also work if the top of the enclosure was tapped with a coarse thread and the screws were inserted from the bottom.
bratan2 years ago
First of all, great instructable!
I have a question about labeling/marking polycarbonate box. If you had to have some writings on the outside (i.e. show volume dial) how would you go about it? Engrave and paint or print adhesive labels?
jhall30 bratan2 years ago
Great question! Not to put down this method of enclosure fabrication (which is wonderful and a great method to learn), there are ways to 3D print your own enclosures, and build labels into them. These cost substantially more than the method in this instructable, but can be good for late prototypes and final projects.

Engraving is an option, too. Dremel's can work wonders here, if you have a steady hand (or can make a stencil to work within). If you have access to a laser cutter, they can also engrave Plexi/Lexan/acrylic (cork/wood/paper/cardboard/leaves...). Those can often be found at hackerspaces (Club Workshop in Denver, for instance), or you might be able to look online and find someone near you willing to engrave for you.

Stick-on labels are great, too!

I have access to the laser cutter option, but if you don't, I'd stick to stickers (hehehe) or mechanical engraving (don't drink espresso before doing this). Either of these methods will work with painting.

Whatever you choose to do, keep making stuff!
Jason-B (author)  bratan2 years ago
On the avr programmer in the picture I used an adhesive label, but if I had the technology to engrave I probably would have used it.
m.d 14072 years ago
nice & good jop O_o
jacob56803 years ago
We used to bend small pieces of plexi ( I know, it's not the same ) for ducting in computers.

We used a stripped toaster oven to heat a strip by holding the plexi just above one of the heating elements. It would make extremely nice bends. Albeit slightly less repeatable than with a jig. ;)
Data6433 years ago
I'm somewhat confused about the Arduino enclosure. In step 3 you say you need 5/8" for the short sides of the enclosure, but in step 5 you use the 1/2" depth. Could you clarify which one is correct, please?
Jason-B (author)  Data6433 years ago
I can see what you mean. The half inch written on the wood indicates the depth of the cut, not the height of the lip it will create. When you heat the Lexan in the jig it almost always bends 1/8" above the wood. To achieve 5/8" high sides I used the 1/2" deep cut. 1/2" + 1/8" = 5/8". Hope this helps.
Data643 Jason-B3 years ago
Thank you, I see it now. Great Instructable, I gave it 5 stars.
mpikas3 years ago
The trick is onto to heat all the way to the ends or at least not to heat them as much. The ends don't have as much material around them to absorb the heat so it's easier to get them hot, a the same time, most of the strength resisting you bending it is in the middle, not the ends. Along those same lines, have you ever noticed that thicker, professionally bent pieces have a slightly larger radius near the edges? That's because they weren't heated as much and if they were they would have overheated before you got a clean bend.

As far as a heat gun goes, it can be done, but it's harder to get a nice bend with it/direct the heat where you really need it. Most people that do have some luck with it bend against something metal that absorbs the heat faster than the plastic which kind of localizes where the plastic gets the hottest.
I work in a plastics shop, we use a heated filament to evenly heat the plastic along the bend line.
gemimile3 years ago
nice !! :)) i'll try to use it on every project i will make.. !! :))

this would help me a lot..

cause enclosures for my pojects really gives me head aches.. haha
bigmark3 years ago
that is too cool!!!
what about a heat gun???
Jason-B (author)  bigmark3 years ago
I tried once and found it difficult to pinpoint where the heat was going. I also tried a propane torch and had the same problem, in addition to setting the wood on fire.
Heat guns don't work on Lexan. I use it a lot in the aviation industry and you can just bend it on a pan break or other similar folding device.
Dr. dB richo7443 years ago
There are also "flexible strip heaters" available fairly cheap, made specifically for (somewhat-precisely) heat-bending (most) sheet plastics...
Of course, actually BUYING a tool to use for an 'ible is dangerously close to "cheating"...
effort bigmark3 years ago
I have used a heat gun for bending plastic for some time. You need one of the 300W craft guns: the paint stripping types are miles too powerful. I usually mask the plastic with pieces of sheet aluminium, held on with bulldog clips, to localise the heated area.
My heat gun was £3 on Ebay, and has a temp of 350C. It's also very good at soldering and desoldering large ICs.
HoldOnTight3 years ago
Fine craftsmanship!
Spike0023 years ago
Nicely done man! I'm a prefectionist when it comes to stuff like this, and that arduino case is perfect lol.

I've been looking for something like lexan to make cases for projects.
Nice job!

I wonder if a heat gun (the kind that looks like a hair dryer, used to peel paint, etc) would be easier to control? I've seen professional jobs where the edges of the lexan were polished (I was told) with a heat gun.
VanGurp3 years ago
Really cool idea. I'll try this on my next project.
I feel so stupid. We used to do similar process when I was a machinist. I didn't even think to do this for small projects.

Thanks for the reminder
shimniok3 years ago
Great instructable! FWIW, step drills work brilliantly for drilling holes in Lexan!
I keep a small bowl of water and a washcloth handy to cool the bends.

Ever try the hotwire method to make your bends?
You could just stick the Scotch Tape on the plastic film. It will then peel off easily with the film. You get the added benefit of more protective layers, and less chance of scratching the work piece.
vanmankline3 years ago
I like your bending jig and design. Much easier than cutting and gluing pieces together to make boxes.

Also, acrylic sheet is a bit cheaper than polycarbonate, and working with it is very similar. Its not as impact resistant as the polycarbonate, but it is still fine for these types of projects.
Did you make that lathe? It's so tiny and ingenious!
Jason-B (author)  irishlyrucked3 years ago
I wish I had that kind of skill, it was a Christmas present; it works awesome. http://www.sherline.com/
Reffner3 years ago
Nice job. Very well done and put together. Very clean and professional looking. I need to do something like this for my UNO. Thanks for the idea!
astroboy9073 years ago
Very good project, just wish I had a torch :) Gotta get some butane for that puppy. And learn how to not burn myself. Anyway I have some plexi/acrylic leftover :) Good project!
very nice write-up. for a polished look to the cut edges without a ton of time spent sanding & polishing, you can "flame polish" the edge with the previously mentioned torch. google will give you more information about this, but the same care should be taken as with bending (i.e. too much heat will cause bubbling). disclaimer, i've not attempted this myself, so I can't comment on the amount of time required, but have seen the results on numerous projects and it is quite impressive.
legwinskij3 years ago
Awesome !
NachoMahma3 years ago
. Excellent
Wonderfully done, this is somthing right up my alley in electronics. I am always hacking apart things and making my own individualized covers for them. This is a method i will soon try. Very clearly explained with detailed instructins and pictures. Keep up the good work! 5*
kelseymh3 years ago
Beautiful project, and very clearly explained! The look of well-built electronics exposed to everyone's view is outstanding.