During our shooter tests over the last week, we have noticed that one of the biggest variables in our ball shooter performance has been the density of the foam balls. In addition to the three balls in the KOP, we purchased two from Andy Mark. The balls seem to vary both in overall density and, much less significantly, in density throughout the ball due to being injection molded.
In order to test our theory, we realized we needed a squishometer. Unfortunately, we were unable to find any on eBay… Undeterred, we built one out of a small level, a robot battery, and a ruler (the squishigraph). To operate the squishometer, the robot battery was held level on top of the ball (right side up to simulate a wheel) and the deformation was recorded. Pictures of our test setup, operated by our Squishographer, Dan, can be found here:
(let me know if you can see them)
We noticed a substantial range of 6.1875" to 6.625"!! Clearly, this was causing much of the variability in our shooter performance (we have verified this by using the same ball). This, however, creates a problem for the competitions as we cannot predict the densities we will encounter.
In order to benefit all teams, we are calling on everyone to build their own squishometers and develop a good global estimate of the range of ball stiffnesses.
To standardize the results, all teams should use a NEW robot battery. We noticed that the battery weights differed by specific part number…and possibly charge level
Please report your results first in your post…followed by a line of asterisks to make it easier to visually parse.
Thanks Teams!! Happy Squishographing.