Home made Trackball

Do you have a free weekend and  an old mouse to throw away? Here’s how you can save the mouse and lose the 2 days – yes, I know, it’s not a big deal, but this is not an economics page.

Before starting the job you must make sure that the optical mouse sensor is functional and the connection to the PC is good, the cable is not interrupted, the socket is not crooked. In case of any damage you can buy a 2EUR mouse. The smaller, the better.

What software will we use?

No, we won’t write mouse software or drivers. Just because we will turn the sensor upside down, we will have to reverse the motion on one of the axes; and for that we need a software.

Google for mouse inverter or sakasa mouse, install what you trust and test the application with the unmodified mouse. Ideally, the application should: be able to reverse one of the axes (of your choice), not to upset the antivirus and not to bring new Trojans to your computer.

The last, optional, step is to install the application on a friend’s computer and let it discover what it is all about. Later you can explain to them that there is a new trend in IT: to simultaneously develop / test your hardware and software: http://www.design-reuse.com/articles/31951/the-power-of-developing-hardware-and-software-in-parallel.html and thank him for his contribution with a juice of whatever he prefers, so as he will not to be upset.

What hardware do we need?

• mouse,
• spacers,
• staples,
• beads – yes, and they are very important for the project,
• toothpaste,
• wood screws,
• prototyping PCB – 2 pieces,
• push buttons – if you want to replace the mouse buttons; I recommend to use larger / wider buttons,
• rubber feet
• the greatest effect piece: a pool ball of the favorite color / number
• superglue or equivalent

What equipment do we need?

First of all soldering equipment, preferably station. To this, must add a cutter, screwdrivers, solder wire, solder flux and desoldering braid plus a few centimeters of insulated wire.

How do we proceed?

Let’s start by disassembling the mouse.

 

We keep the electronic board and the USB cable.

Desolder the buttons, the USB cable and other important components then glue the lens with superglue. This will ensure the stability of the lens position in the event of an earthquake, transport or more vigorous use.

It is preferable not to detach the LED, the optical sensor and the parts that ensure the smooth operation of the first two.

 

Then we cut an octagon slightly smaller than the pool ball, into the protoboard.

Then we take the staples …

… and the beads …

… and we solder them as in the pictures below.

Now you have to do a test mount using four spacers, the protoboards and the pool ball as below.

With this mount we can determine the position of the buttons, but first of all, we can find the optimal placement of the sensor board. I recommend you to experience some positions and heights because it is very important to find the best position of the optical sensor relatively to the pool ball.

Ah, yes! Do not use the orange ball! It seems that cheap mouse sensors go wrong on orange and glossy surfaces.

Here are some pictures from the experimentation phase:

Once you have determined the position of the sensor, fix the mouse board using spacers and screws. You may need to widen or drill new holes in the protoboard to place the sensor in the optimal position.

Then solder the new buttons on the protoboard and connect them with wires to the electrical pads of the original buttons. If you decide to keep the scroll wheel you must pay attention to the order of the connections.

Add four rubber feet and the job is done:

 

Translated from Romanian.  Enjoy! 😀