Ball hard spot

Anyone notice that there a hard spot on the ball? When we tested our luncher it work very well until the luncher hit the hard spot when went way over the targer :ahh: Any thoughes about the spot on the ball?

belly button? Its where the plastic is injected into the mold when the ball is made.

yeah about that hard spot…i guess just another variable in the game as far as what your robot is designed to do with the ball and how that hard spot may come into consideration to your method.

Will it be that much of an issue you think?

well we played around with how much it might affect the “play” of the ball. it seems that the hard spot tends to allow for the ball to want to have that hard spot always closest to the ground, or in other words could cause some nasty spin. The other thing we looked at was if we were to use a roller system how the compression on that hard spot versus anywhere else on the ball and how much of a impact that would make in being able to grab the ball using that roller system which would basicly compress the ball by a total of about 1" to get a good grip on the ball. However it is all up to you and your team to consider these kinds of factors along with possible compression of balls throughout the matches.

I know that the compression of dual wheels will have some affect on the grip. I dont think that the tiny knob (belly button) will give it enough spin to calculate marginal error.

A belly button is a good thing to call it. Our teammates kept poking it. If it affects the launching of the ball, that’s just another one of those extraneous variables that make things interesting. :slight_smile:

The heavy spot does throw off the center of gravity(COG). So if you are thinking of the “rifling” the barrel of the shooter to give the ball spin so it would stablize, be aware that with COG not exactly the center of the ball, the spin might actually cause it to swirve all over the place instead of going straight.

If its any help, our ball is getting pretty well worn and I don’t think the belly button as its being called is noticeably different any more. It might go away with wear.

With hours of testing today, it has been determined that the hard spot is the cause of nearly all inaccuracy in shooting. With all other conditions well controlled, I estimate the hard spot will cause approximately 1 in 12 balls to miss.

What kind of launcher do you have? Are using fly wheels(like a baseball machind)

What are the odds that it will hit that in the acutal competition?

Well, I don’t think the odds are any different from in testing. During testing, if we control all the conditions, roughly 1 out of every 12 times the ball will end up in a significantly different location (like missing the hole all together) and we have colcluded this is due to the hard spot contacting the pitching wheel. We arrived at this conclusion by controlling all the other conditions to the best of our ability.

Which way the navel ends up in your shooter depends on how the balls are loaded, and how you pick them up.

Since the navel is probabally a dense spot of plastic in the foam ball, its should be heavier. therefore a ball on the floor would tend to roll till the navel is down, like an out of balance wheel will center itself with the heavy side down.

So depending on how you load your shooter for auton mode, and how the balls move through your machine, the navel my end up in random positions, or it may tend to gravitate towards one orientation in your shooter mechanism.