I mentioned in my last blog post about the base of our robot had warped due to the load being applied to it. We decided to use 3mm MDF, which (after experimenting with it during Eurobot) I figured wouldn’t be the best thickness, but we still went with it. I had hoped that we would double up the layer, so that it would be 6mm thick instead, but we left it as 3mm. We mounted the battery to the center of the top of this base, and the battery does weigh a good 0.8kg, so the weight of this warped the base, making it dip in the middle. This caused both motor brackets to be angled inward, and, as result, the wheels were angled, which was causing them to fall off after a few rotations.
We decided we would need to replace this base, and started searching for some spare 6mm wood that we may have had lying around our houses. The best we could find was some 10mm MDF, but we figured that this wouldn’t need to be replaced as it should easily handle the load.
We cut out the shape of the base, and used the old base to mark up where the holes went. We then proceeded to drill out these holes, and a new base was ready within an hour. The components were placed onto the new base, and with one ball transfer unit, we tested a code we had written to test out the stopping distance of the motors. With the warped base, the distance was not accurate at all, but with the new base, even with only one ball transfer unit, the distance was about 300mm every time.
We’re hoping to try out the makeshift spacers one more time – we’re hoping that the adhesive will have a stronger hold if we let it dry for a longer period – and we will test this again. However, if it fails again, we have found a company who sell spacers but will, for an extra cost, thread them for us, to our requirements. Although this would mean spending more money, a solution is needed for the ball transfer units, as without spacers to extend the shaft, the robot will not be able to work properly with the compass.