Cargo diameter/inflation consistency and our placement device

I’ve read in the game manual that cargo is generally 13.5 inches in diameter but may be 1/2" off either way (larger or smaller). How are the game officials going to maintain cargo consistency in size? My rookie team over inflated the cargo quite easily. My veteran team had a stroke when the ball would not fit into their cargo deployment system. I’m having a stroke at this late date because our waterjetted system will have problems with cargo if the cargo is not inflated to a consistent basis.
I’m not complaining. If we have problems, we’ll work around them. I’m just a teacher, not an engineer; so this kind of thing tends to get put on the front burner for me.

I need a brew!:thinking:

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Question 180 answered that:

Bottom line for developing is to design and test your cargo mechanism with at least a +/- .5" tolerance in ball diameter.
Change your ball inflation to test with sizes at least 12.5" to 13.5"
We have two balls for testing, one is at 13.5" and the other is at 12"

As an aside, after a full day of all our different robot mechanisms pummeling, squashing, and driving over the field balls, I doubt that the balls will remain round.


we made a major design change in our robot in the past several days…now it will tolerate CARGO from around 8" diameter to about 14 or 14.5" diameter. But it won’t pick it up off the floor :slight_smile:

Thanks guys! I think we’re ok up to about 14.5 but anything over that is problematic at best. I’m thinking some grinding or cutting may be in order :slight_smile:

This shouldn’t be all that hard to implement at events. Hole cut outs at 13.5" and 12.4" painted green and red respectively. If it passes through the green and stops at the red it’s good. Every hour or two run a bunch through there.

Disclaimer: I have never volunteered for field reset and don’t know how much of a burden this would actually be.


What i would probably do is make 2 types of sizing rings at 12.5-13.5 and give each member of field reset one of the two, and just have people run balls when they have time and as they are moving them. It won’t be perfect but it should catch most out of tolerance balls fairly quickly.

In general, after years of experience with inflated game pieces at FIRST events, I would assume that you will routinely have to deal with game pieces that are outside the stated tolerance in the manual. I cannot recall a game where FIRST used inflated game pieces that were actually held to their specification across all events. 2014 and 2011 stand out as examples where game pieces were very often overinflated.

Even if there is a gauge it can be misused. In 2011 there was a dimension in the manual the tubes were to be inflated to fit. The intended use was to place the deflated tube in the gauge, and then inflate until the tube touches the walls of the gauge. At many events, volunteers inflated the tubes and then forced them into the gauge afterward to demonstrate compliance. These tubes were over-inflated. The point of this anecdote isn’t to throw volunteers under the bus, but to demonstrate how even reasonable sounding ideas such as gauges may not sufficiently control tolerance on these items.

I like the idea of a go-nogo gauge for field staff. I’ve designed a few for dimensional inspection of castings at work, so in my opinion the large diameter should be colored green (Go, cargo will fit through) and the small diameter red (Nogo, cargo will not fit through). Generally this is more intuitive for the pass/fail criteria of the gauge (fitting through the hole).

I just had an email flurry with our FIRST in Texas Northern Director. The gauges will be used at our North Texas events. Ahh…I can breathe now. :smile: