This Instructable will show you how to make a one-piece sheet metal cooling tray for a laptop. Raising the back of the machine an inch or two allows for enough air circulation and ventilation to keep the computer cool and happy, (and your fingers from cooking). An added benefit is that it tilts the keyboard (10 degrees in this case) for a more comfortable typing position.
This tray is built for the dimensions of a huge Dell. I went with a truss inspired pattern of triangles with a "subtle" all-seeing eye to watch over my machine. Measure your preferred computer and design accordingly. Rule of thumb: the more holes the better, as long as it doesn't compromise the structure or the fold lines.
Pay attention to where the laptop's "feet" are. You'll want them to sit on a solid surface (not over a hole) to prevent scratching the machine or rocking.
The front lip height is important. If you're designing for a Mac the lip will need to be much lower as they are much thinner machines. You don't want to rest your palms on that edge.
I designed this in Autodesk's Inventor as a sheet metal part file. I used 18 gauge cold rolled (cold finished) steel. Stainless or soft aluminum might work just as well if they are thin.
Step 1: Cut Out Your Flat Pattern.
Cut out your flat pattern. For clean lines use a waterjet, laser cutter, or plasma cutter. If you don't have access to one of these machines, they are very common in sheet metal shops. Call around in your area and ask for a quote.
Note: if you plan to outsource the cutting, you may want to consider first printing out a template to ensure your measurements are correct and your bends are in the right place.
*If you want to do this by hand, rock on. Time to make friends with drill bits, hole saws, grinders, and files. BE CAREFUL when working with sheet metal. It cuts flesh effortlessly.
I cut this pattern out on a Omax waterjet.
Step 2: Remove Sharp, Pokey Bits.
The waterjet often leaves little razor sharp pokey bits (tabs) where it cuts out openings. I found that wire cutters make quick work of removing these. Follow up with a metal flat file until smooth.
Step 3: Clean and Prep for Bending
The waterjet uses water and abrasive garnet (sand) to cut the steel. Because of this mixture, steel rusts surprisingly quickly. Before bending you want to clean and prep your flat pattern. It's much easier to work with while flat.
*Don't forget to wear some good safety glasses and hearing protection.
When sanding, it helps to clamp the piece onto your work surface with a piece of wood as a backer (so that you don't sand your table).
I used a pneumatic right angle grinder with a Roloc disc but fine sandpaper or Scotch-Brite work great. With whatever method you use you'll want to pay attention to direction of the sanding lines as they will be visible on the file product. I started on the bottom side to get the technique down and then flipped it over to finish the front.
Step 4: Time to Bend
I bent this tray using a hand cranked sheet metal press brake. Although if you're careful you can do it over the edge of the table. In this case the perforated lines not only give you a good guide for where to bend, but also help keep the corners tight.
Start by bending the back rectangular section.
Next, clamp your steel in the vice like so.
These little tabs need to be bent down to line up with corresponding holes on the sides, so make sure everything is square and the right height.
For this I used a sheet metal hammer that has a special flat face as to not mare (dimple) the steel. A regular hammer or block of wood could work as well. Repeat on the opposite side.
Step 5: Bend the Sides and the Front Lip.
Next, carefully bend the sides making sure not to damage the rear bend. If at any point the sheet metal gets tweaked or dented from bending, use the sheet metal hammer on a strong flat surface to straighten things out before you move on.
Step 6: Aligning and Riveting Tabs
If you're lucky, the holes in the tabs line-up with the holes in the sides.
If not, spend a little more time with the sheet metal hammer and an awl (or nail) to tweak things into place. Sheet metal moves a surprising amount so go easy with it.
Once you get everything lined up you can rivet the tabs together. I used 1/8" aluminum rivets in 1/8" holes.
Line up your holes. Insert your rivet and slowly squeeze the rivet gun. Make sure to stay perpendicular to your holes.
*For those who don't know what a pop rivet is: Also known as a blind rivet, they are a great quick and permanent fastener that is easily drilled out should you need to. They work by drawing the steel shaft through the aluminum sleeve to squeeze the parts together. The shaft snaps once it reaches the right pressure and you're left with a clean minimal rivet head.
Step 7: Finish It Up.
Give your cooling tray a final look over and test fit with your computer. Make any final tweaks and sand/scotch bright any dings or scrapes. Clear coat the steel to prevent rust. Enjoy!