Integrating Electronics Into Your Next Project: Part 3

This article was originally written for The Best Case Scenario. Read the original article here!

Welcome to part 3 of our Integrating Electronics miniseries! In part 1 we gathered some basic info on the project and in part 2 we discussed the hardware and software side of it. Here in part 3 we'll be doing the modding to tie it all together! Read more....
 

Modding

This part is where we get down to the nitty-gritty. Here's where we break out the tools and parts and get some modding done! I'm using parts in this mod that are easy to use and easy to come by so just about anyone can duplicate it, even with a tight budget.

For this project we'll be motorizing the door on the Cooler Master CM Storm Enforcer case.

Here's one of the door's hinges. I'll show how to modify this later on in the project.

There are 2 small magnets glued into the door that need to be removed because they're too strong for the weak micro servo and linkage to overcome. They're there to hold the door shut when it's not in use, but we won't be needing them anymore.

Button Mounting

I had this panel-mount momentary button laying around that will be perfect for this mod. The style fits the case and it's already terminated with a 2-pin connector which will make it easy to connect later on.

We'll put it in the lower right hand corner of the front panel. It'll fit nice and be out of the way.

I used a step drill bit to drill the mounting hole. Step bits come in very handy. They allow you to start off with a small hole and work to a bigger one without the need to stop and change your drill size.

Once you've drilled the hole to the proper size the button just snaps into place.

And here's how it looks with the front panel reinstalled onto the case. It's clean and out of the way.

Servo Mounting

The next item of business is mounting the servo to the chassis. I went about this in a way that's simple and cost-effective. I'm sure it can be approved upon, but it works well as you'll see.

I had this heatsink laying around that I decided to use for servo mounts.

You can see the arms on the heatsink are the perfect length for mounting the servo.

The next 5 images show how I modified the heatsink to mount the servo to the chassis. The servo is mounted in the lower 5.25" drive bay, in line with the lower door hinge.

Linkage Setup

The next step was to cut a notch in the case for the linkage arm to run through. Cutting a wide slot was necessary due to the movement of the hinge. Had a single hole been drilled instead, the linkage would have bound up.

The linkage will consist of a single-armed servo horn and a small piece of stiff modeling wire.

The second hole of the servo horn needed to be drilled out larger so that the wire would fit through it. I chose the second hole rather than the first because I wanted to be sure there would be enough material left surrounding the wire.

I used a small pair of needle nose pliers to make a "Z" bend in one end of the wire. This will allow it to sit securely into the horn without falling out.

Next I took the pliers and made a few more bends to get the wire to mate to the door hinge properly.

The next step is to drill a hole in the hinge for the other end of the linkage wire.

I also found that I needed to file out a little of the plastic under the hinge for clearance for the linkage arm.

Here is the servo with the linkage rod installed. You'll need to play around with the position of the servo horn on the servo and the open and closed positions in the coding to get the door to open and close just right for your particular application.

Once again I've got the setup connected to my Power House mod as there is no hardware or PSU in this case to use.

And of course here's a little video of it in action. The door moves faster when it's close to being closed because of the hinge setup. There wasn't much travel in the hinge to work with, and there is some play in the wire itself. A simple fix would be to use a bigger servo and stiffer wire or another type of linkage, but then you run into clearance issues with the side panel and front panel. Also you'll notice that the door doesn't close 100%. This is also due to the linkage setup, but could possibly be remedied with different parts.

Stay tuned for the final part of this series where I'll show you how to design, etch and assemble a circuit board for this project!