This is the beginning about a project to convert a optical mouse into a Trackball for a cheap multimedia kiosk peripheral. We can´t use the mouse as the original way, because it can be damaged or stolen. So we propose this PROTOTYPE to make some experiments and see if it works. Ok so what we need is:
1 Empty Roll-on deodorant
1 Cutting pliers
1 Glue or sillicon pistol
1 Optical Mouse
Step 1: Getting the Ball
Ok so we need the ball of the roll-on deodorant so we take our cutter and simple cut the upper part of the dedorant case where ball is. Not to be necessary perfect in the cut
Important: you need to leave some material where the ball can support itself without touching the superfice where it will be rested.
Step 2: Nivelate the Surface
Once we have our trackball, we need to cut off the excedent material in order to make the rollon ball closer to the surface. This is because the optical mouse sensor only detects movement in a range less than 1 cm. So we take our Cutting pliers and we start making little cuts in order to reduce the material. Be carefull to not let the ball touch the surface if you rest on a flat horizontal surface, because it this happens the friction will not let the ball moves freely.
Step 3: Attach to the Mouse
When you have your trackball ready it's time to glue it to the mouse. Take your optical mouse downwards where the optical sensor is. Most of the optical mouse have a red LED near to the sensor, a few other use invisible infrared LED. This do not affect the functionallity. Center your trackball with the sensor aperture and glue it. Remember to dont let the ball touch the mouse surface, it have a distance between about of 3 mm.
Step 4: Done!
You are DONE! , you just need to plug in your mouse and you can start experimenting with your trackball. There will be an issue about your new trackball mouse, it have an inverted axis, X or Y depends in how your grab the mouse. Now we are trying to find a software solution or even an electronic hack to correct this issue. If you know how to do it please share with us and the comunity. About the clicking, our next work it's to solder new switch buttons and attach it in a ergonomic way. If you make yours please let us know!
Here is a video with the trackball working: