Who would have thought, decades ago, that someday we would be throwing away floppy disks and keeping the box they came in? The picture shows an electronic project chassis I made from a plastic case that Sony floppy disks came in. This instructable shows how to re-purpose this case. (Actually, I have not thrown out the floppies yet, hoping that they, too, can be repurposed.)
Step 1: Obtain an Old Floppy Disk Case or Other Plastic Box
One picture above shows an open Sony Floppy disk case. It consists of three pieces that all easily snap apart for machining and wiring. There is an internal divider that can be cut out if it is in the way. I have found that the plastic in these cases is easy to machine, i.e., drill and saw, without melting or splitting. Although this instructable focuses on using a Sony floppy disk case, the basic ideas are applicable to making an electronic chassis out of other plastic items like file card boxes, soap bar cases, and even metal boxes. There are times when you might want a metal chassis, like when working with high frequencies or for ruggedness, but often plastic will work ok. At the very least, using plastic should be cheaper than using a real metal chassis.
Step 2: What's Needed
- A schematic of the electronic project you want to put in the chassis.
- Identification of the items (controls, meters, switches, jacks, leds, etc) that you want to mount on the front, rear, side, and bottom chassis panels. I like to have all parts on hand before I start the layout and machining to minimize errors.
- The free drafting program called "InkScape" if you want to have a more professional looking panel. There are tutorials on-line for using InkScape as well as another instructable for making panels using InkScape. There was also a good article on making panels in a 2013 "Nuts and Volts" magazine article. Alternately, you can use Dymo stick-on labels or no labels at all.
- Paper "card stock". This is heavy paper (110 lb), typically used to make homemade greeting cards.
- "Blue" painter's tape.
- A Sharpie pen marker to mark on the painter's tape.
- A 9/64" drill bit.
- A drill or drill press.
- A jig saw if some cutouts are not circular. I used a Bosch jig saw with a "T101A0" blade which is narrow in width, fine-toothed, and has no "set".
- A "step" drill bit. The picture shows a set of three step drill bits that allow you to drill progressively larger holes as required for the part being mounted. By using a step bit, you don't have to keep changing out individual drill bits. You can get a set of three for about $15 at Harbor Freight. Generally, I only use the smallest of the three. Certainly, you can just use use ordinary drill bits to obtain the needed hole diameter.
- A round, "rat-tailed", file for enlarging round holes if required.
- A flat file for enlarging non-round holes, if required.
- Krylon spray adhesive, or similar, for attaching the paper front panel to the chassis. Other glues may work as well.
- A printer to print out the paper panel. I used a color laser, but an ink jet may work also.
Step 3: Make the Panel Using InkScape
You may skip using InkScape, if desired, and just mark the chassis for drilling as described in the next step. Using InkScape, make the front panel actual size. Layout all of the controls and add nomenclature. Pay attention to where the case divider is located unless you've removed it. Wherever there will be a hole, make a "crosshair" to identify the center of the hole so you can transfer the hole to the chassis later. This is all pretty easy, but there is a "learning" curve with InkScape. The picture shows the resultant laser printout. I have already cutout one of the 3 identical panels for use during chassis marking. Depending upon how you do the next steps, you may only need one copy.
Step 4: Mark the Chassis for Drilling/Machining
If you're using InkScape, tape a copy of the front panel design to the chassis as shown in the picture. If all of the holes are round, you can simply drill through the template, not worrying about accidently ruining the template since you have additional copies for the final glue down. Since I had a rectangular meter cutout, I was pretty sure that jig sawing the opening would ruin the template so that's why I made spares. Also, before using the template, I taped the front chassis panel with blue painter's tape as shown. If you don't want to use InkScape, simply mark your crosshairs on the blue tape and go from there. Then, you would either use Dymo labels or NO labels. I removed the template before machining as I was concerned that the paper template would move around and the holes would not be correct. To transfer the marks from the template to the blue tape, simply make a small hole in each template crosshair and mark through to the blue tape with a ball point or Sharpie pen.
Step 5: Drill the Holes
I started all holes with a 9/64" drill bit. This is small enough to not crack the plastic yet large enough to provide a starting hole for the step drill bit used to enlarge the hole. For the rectangular meter cutout, I used the step drill bit to provide a hole large enough for the jig saw blade. Drilling and using the jig saw requires some degree of patience. You don't want to make the holes too large so go slowly. A "lesson-learned" was that I tended to make the round holes slightly too small and had to use the round, rat-tailed, file for a good fit during part installation Use a flat file for a good fit for a non-circular part. In addition to the front panel, you may need to add holes on the rear/side/bottom panels for rubber feet and other parts such as cable entry grommets.
Step 6: Adhere the Paper Panel and Attach the Hardware
Using the spray adhesive or other glue, attach the paper front panel to the machined chassis. Using an Xacto or other hobby knife, cut out the holes. The hardware you'll be attaching will usually cover any "rough" cutouts. For my first attempt, I added clear "contact" paper over the paper hoping to make the front panel less likely to be damaged. This didn't work well because the contact paper doesn't adhere very well to the paper. Then, when I was attaching the hardware, the contact paper tended to separate leaving a "bubble". Now, I'm just using the paper by itself, hoping that it will last as long as I do. I have considered spraying over the paper with some kind of lacquer coating but don't know that it's necessary.
Step 7: Using the Floppy Disk Case With Dymo Labels
This picture shows another Sony floppy disk case project I made before I started using InkScape. Here, the electronics were mounted on top rather than instead. The controls for this variable power supply were simple enough that the project didn't really need any labels, but I did add Dymo labels.