Modifications to Robot Arm for Opto Coupler Feedback, OWI 535, Edge etc

Step 3: Modifying the Encoder Gear.

Picture of Modifying the Encoder Gear.
Now we have to modify one of the gear wheels, the brown one in fact, to turn it into the encoder wheel.

The very nice people who made this gear wheel, left 6 small circular markings on the underside of the gear wheel, these are in a perfect position for the holes that we want. Basically the more holes we have, the better the final resolution. I certainly wouldnt advise going for more then 6 holes, as it would leave the wheel too weak. The first picture shows the 6 markings, highlighted with a pen.

Great care needs to be taken with the next step, as the wheel can be easily damaged, Please DONT be tempted to drill each hole out in one go, The finished hole size is 4mm. I first took a piece of wood, and drilled a hole big enough to take the smaller half of the gear wheel, to allow the larger face to sit on a flat surface. The first hole i drilled was 1.5mm, this was my pilot hole, the next size up was 2.5mm, and for the last drilling, i did this by hand holding the drill bit with a cloth wrapped around it. The hole being so close to the edge, i didnt want the risk of the drill  bit grabbing, and wrecking the gear wheel.

With the gear wheel drilled, we can now move onto the next step.