Game piece inflation

[notmattlythgoe]

Originally Posted by Brandon_L

Officially, the balls are inflated to the point where they look about right and thats it.

Although I agree there should be a sizing box 100%, this is the first I'm hearing of it being actually used.

+1 GTRW Crew

There was a sizing box used for Logomotion . Unfortunately it didn't help because people were still inflating the tubes until they were overflowing from the box and were bigger than most teams expected.

[Jim Wilks]

The sizing ring had a hole exactly 25" in diameter. When a few teams at GTRW complained about the ball sizes, they were checked and a few were found to be oversized. Those ones were deflated.

Some teams cam by and used the sizing ring on their practice balls as well.

The ring went in the robot inspectors case.

[Patrick Flynn]

Does anyone else think that a sizing box is not the way to go here? We have no idea the tolerances that these balls are designed at. If the balls are +/- .5in a sizing box would lead to over and under inflated balls, and then everyone would be complaining about that.

I think there is a bunch of confusion here.
Having all balls the same size in diameter would lead to different levels of inflation.
Having all balls inflated to the same PSI would lead to different sizes, in diameter.

Simply put the tolerances on there balls are not +/-.0000000001 There is no way to have all these balls be the same size and same pressure.

[notmattlythgoe]

Originally Posted by Patrick Flynn

Does anyone else think that a sizing box is not the way to go here? We have no idea the tolerances that these balls are designed at. If the balls are +/- .5in a sizing box would lead to over and under inflated balls, and then everyone would be complaining about that.

I think there is a bunch of confusion here.
Having all balls the same size in diameter would lead to different levels of inflation.
Having all balls inflated to the same PSI would lead to different sizes, in diameter.

Simply put the tolerances on there balls are not +/-.0000000001 There is no way to have all these balls be the same size and same pressure.

The rules state nothing about ball pressure, but they do state an approximate size. And assuming that all of the covers are approximately the same size the balls should be inflated to around the same size according to the inflation guide. So there is no argument backing pressures since the rules state nothing about it.

[jman4747]

We really should not have a problem putting a ball in a box and pumping it up till it touches the sides.

I don't see why you can't just pump them up in the morning and check them at lunch each day and be done. Or even just once a day (I'm assuming they may lose some air getting hit and squished all day).

The rules say approximately 2ft diameter. Excuse me for designing for 23"-25".

[Annatreptic]

They were extremely inflated at teh Glacier Peak PNW regional as well. So inflated in fact, that it started to continuously stall our motor and wouldn't allow us to gather the balls at all. We want to put some slop in our pneumatic mounts to our arm to try to fix this problem, any other teams done things to help this problem?

[MarcD79]

This thread can go on and on, but the one thing to remember is that according to the Filed manual, the balls should be inflated to the point where the zipper is not touching itself, nor stretched into a football shape. They are to be inflated where the zipper is slight pulled apart where the inflating plug can be inserted. The zipper should be able to be pulled closed with some slight resistance. I did not receive any complaints at the Groton District event. I checked all balls often & they were consistent. We did have 2 balls checked at the beginning of the Eliminations & found to be slightly over-inflated by a volunteer who was just trying to keep up & was pumping them up rapidly. After that they seemed to be consistent. They will be scrutinized at the Southington District Event to be properly inflated.

[tickspe15]

Originally Posted by Annatreptic

They were extremely inflated at teh Glacier Peak PNW regional as well. So inflated in fact, that it started to continuously stall our motor and wouldn't allow us to gather the balls at all. We want to put some slop in our pneumatic mounts to our arm to try to fix this problem, any other teams done things to help this problem?

we noticed that the balls were more inflated than we expected at auburn mountain view during week 1 and upon further testing found problems similar to the ones you describe. We then altered our intake by moving the roller up about an inch to decrease ball compression and avoided problems at glacier peak. Though the balls may be over inflated they have been consistent at PNW event

[Ether]

Has anybody out there actually measured the difference in pressure between a properly inflated ball and a slightly over-inflated (and under-inflated) one?

Is it a large enough difference that it could be reliably measured with a relatively inexpensive gauge at the events?

[MrForbes]

Originally Posted by Annatreptic

They were extremely inflated at teh Glacier Peak PNW regional as well. So inflated in fact, that it started to continuously stall our motor and wouldn't allow us to gather the balls at all. We want to put some slop in our pneumatic mounts to our arm to try to fix this problem, any other teams done things to help this problem?

Last week, 4183 lengthened their pickup arms an inch to allow the more-inflated balls to fit without stalling the motor.

Measuring the pressure would require a special fitting or gauge, although it wouldn't be too hard to make something to do it. 1/4" pneumatic tubing fits into the inflation hole in the ball.

The extent of wrinkling at the seams of the ball gives an indication of how full it is...until the wrinkles go away entirely, then who knows?

The balls aren't exactly round, either...they're sort of cube shaped.

I think this is a game where you need to take a lot of effort to make sure your robot will work with the game pieces, whatever they end up being like at the competitions. If you didn't, you're going to have problems. The low goal is a good option if you can't shoot into the high goal reliably.

[Brandon Holley]

Originally Posted by Patrick Flynn

Does anyone else think that a sizing box is not the way to go here? We have no idea the tolerances that these balls are designed at. If the balls are +/- .5in a sizing box would lead to over and under inflated balls, and then everyone would be complaining about that.

I think there is a bunch of confusion here.
Having all balls the same size in diameter would lead to different levels of inflation.
Having all balls inflated to the same PSI would lead to different sizes, in diameter.

Simply put the tolerances on there balls are not +/-.0000000001 There is no way to have all these balls be the same size and same pressure.

Has this actually been tried out tho? Its all speculation until you see the actual results.

I don't think anyone is asking for 10 decimal places of tolerance on the diameter.... However a single decimal place or 2 would certainly be welcome.

Honestly I would take one or the other if it helps consistency in an event and event to event. Right now, we don't have either besides a general 'look' and 'feel'.

-Brando

[tr6scott]

Remember this video was to address this concern. http://youtu.be/Azc8AKzgEwE

The sportogo makes them as 25" balls, AndyMark sells them as 2' balls.

They must loose an inch in Indiana air.

[Bochek]

Originally Posted by tr6scott

Remember this video was to address this concern. http://youtu.be/Azc8AKzgEwE

The sportogo makes them as 25" balls, AndyMark sells them as 2' balls.

They must loose an inch in Indiana air.

None of the balls at Palmetto looked even close to the example in the video, some where stretching the stiches at the seams.

By saturday about 1/2 the balls on the field had been corrected. but most where still oversized.

[Brandon_L]

Originally Posted by tr6scott

Remember this video was to address this concern. http://youtu.be/Azc8AKzgEwE

The sportogo makes them as 25" balls, AndyMark sells them as 2' balls.

They must loose an inch in Indiana air.

So in the manual, they state 24" ball (2ft). In the video, they say 25" ball. In the manufacturer specs, it says 25" ball, and andymark sells it as 2ft ball.

The video tells us literally to inflate it till it looks 'just right'

So which is it, GDC? Why is this such a hard question to answer?

[Patrick Flynn]

Originally Posted by Brandon Holley

Has this actually been tried out tho? Its all speculation until you see the actual results.

I don't think anyone is asking for 10 decimal places of tolerance on the diameter.... However a single decimal place or 2 would certainly be welcome.

Honestly I would take one or the other if it helps consistency in an event and event to event. Right now, we don't have either besides a general 'look' and 'feel'.

-Brando

The actual result can be seem using chemistry.

Lets say we have a 25'' Sportlogo ball, and a 24'' AndyMark ball, I know their the same ball
R1=12.5in
R2=12in
V1=(4/3)pi(r^3)
V1=8181.23in^3
V2=7238.23in^3

Ideal Gas Law, PV=nrT
Assume (nrT) is constant between two balls.
We have have (P1)(V1)=(P2)(V2)
From above (P1)(8181.23)=(P2)(7238)
Notice the two pressures cannot be the same.
Lets say we inflate one ball to P1=7.5PSI, NCAA Basketball recommendation pressure
Now we see that P2= 8.477PSI

What does our result show? Well the Smaller diameter ball is at a greater pressure. Meaning that it is firmer.
If you try to instead control the pressure you'll see that you get stuck with a different ball diameter.