Poor Big Ball Quality

When we tried to inflate the large balls to 15.5 inches, most of them popped. Yesterday, we saw lots of busted balls at the competition (Austin Toss Up).

This is not a question. I’ve moved the post to the general forum where other members of the community can discuss.

When inflating the large balls, inflate them to a point where they are reasonably firm. You should need to put a little bit of force to make them indent, but they shouldn’t be so inflated so that you can’t impress your finger on them. It’s the same concept with pumping up the tires on your bike, you should be able to press them in a little bit (although less so than with the large balls), but not too easily.

The large balls should be inflating to the right circumference. Perhaps they’re inflating the balls too fast. I’ve found that your average air compressor will work fine, as will a traditional hand pump, so long as you are compressing at a rate that’s not too fast (to prevent popping), but not too slow (for speed’s sake).

I’ve pumped up at least 2 dozen large balls, our club has pumped up 4 field sets and 3 extra large balls from the registration kits and have only had two (maybe three, can’t remember) defects, in which the large balls had small leaks. I’m fairly certain one of the large balls that had a leak was a result of a robot accidently scraping the large ball, creating a crack.

I also feel scared using those large balls, especially since we’ve only had 2, and one popped. Makes me wonder if overdrive balls had these same problems.

We’ve had a lot of problems with the large balls popping on a seam, and leaking, I think we have 5 or 6 balls that have been ruined. At a tournament I was at this past weekend they had the balls under inflated per spec. and we were told there was a ruling by REC that the large balls could be used at a tournament undersized, they still needed to be large enough to not fit under the bars, and firmly inflated but they were definitively smaller than 15.5"


Trying to accurately measure the diameter of a big ball being inflated is not that easy if you do not have some sort of measuring jig, especially when they are not perfectly spherical. From some peoples comments, it sounds like inflating to the correct size could be terminal for some big balls.

Pneumatic tyres (for example car or bike tyres) are inflated to a safe operating pressure, rather than to a size. Can anyone please suggest a safe pressure to inflate the big balls to?

Thanks, Paul

Every tournament should have the robot sizing tool. If the big ball has the recommended 16.5" diameter then it should come within an inch or two of each limit of the sizing box.

At this year’s Houston VEX, the setup crew used a simple but effective way of measuring the large balls after inflation. They used two chairs and placed them back-to-back with a 15.5" gap in between them. When the balls touched both sides, they knew they had the correct size.

chairs a.jpg

Good idea to measure the size.

I too noted the non-spherical big ball shape and wonder if inflation to “size” should be checked along the most significant axis only. Agree a safe pressure would be handy but often measuring low pressures isn’t easy!

Hey 9090, we have had a lot of the same problems. I took have been re-inflating several of them, say 3 or 4 that work alright for a few hours, but are always flat after a day or so. I found a small hole on one of them, and stuck a small piece of packing tape over it, and no problems so far!

Yes, all of our big ball bursted on seams. Looks like blue big ball had better quality than red balls.

We tried too, but didn’t last long.

I don’t know if we have blown them up all the way, but ours have not popped or broken. They do let lots of air out (after a 3hr period), and need re-pumped, but never have they broken. We just use our mouth and do as far as we can until it is virtually impossible. I think that is about right… I should actually figure out if it is a 15.5" diameter one of these days.

Our large balls have gotten in a weird egg shape before. I basically just squeezed it very hard, and put it back into a circle shape. It works for now :d

Do you all blow the large balls up with your mouth, or with a pump. If you use a pump, where did you get yours?

Our team uses a bike pump and have popped one ball.

Another ball had the weight on the inside explode and now there’s sand all over the inside.

These field objects were not very well built.

I personally think VEX should allow duct tape for minor fixes.

Anyone found a nice way to fix holes using something less obvious?

Of the big balls in my field kit at least 2 had holes to start with and in the next few months of hard testing I doubt the rest will fair well.

We have had a very similar experience. All four red balls have popped or leak, but only one of the blue balls has a small leak and the remaining three are fine.

WE tried duct tape and didn’t work well. It only last very short period.

How do you use a bike pump? Did you have to purchase an adapter?

Nah it came with one. Not sure exactly how it works somebody else did it, but they were going super slow and it started to split before there was even any real pressure on the inside.