2016 Boulder weight issue

[catmanjake]

All,
Has anyone received multiple FIRST boulders or ones from Gopher and compared the weight? We received 6 of the Gopher balls today and they are different weights and only 1 was close to the official FIRST boulder we received in our Kit of Parts. Some of the weights are so different that we think that they will shoot differently. Let me know your thoughts.

[Ether]

Originally Posted by catmanjake

Some of the weights are so different that we think that they will shoot differently.

Please post the weights you measured.

[catmanjake]

Official FIRST boulder - 292 grams
Gopher boulders were 326, 358, 359, 359, 362 and 388 grams.

[Jared Russell]

How do they compare in terms of surface texture, firmness, and size?

[wilful]

perhaps the colors are related to the mass?
This is an issue with frisbees where the titanium in the dye make the white frisbees stiffer.

[catmanjake]

We are not finding any other real difference other than the weight. We ordered the 6 pack rainbow colored balls the same day of kickoff and they just arrived today. Hoping others can check theirs to compare as well. We would also like to know if teams have a couple of the official boulders to see what the weights are of theirs.

[Hallry]

Originally Posted by catmanjake

Gopher boulders were 326, 358, 359, 359, 362 and 388 grams.

Originally Posted by catmanjake

We are not finding any other real difference other than the weight. We ordered the 6 pack rainbow colored balls the same day of kickoff and they just arrived today. Hoping others can check theirs to compare as well. We would also like to know if teams have a couple of the official boulders to see what the weights are of theirs.

Can you label the weights you posted with that Boulder's specific color? I'm interested to see if other teams who also bought the rainbow 6 pack find that their respectively colored Boulders weigh the same.

[bobcroucher]

Here are the weights for ours, our scale only measures to the nearest 5g:

Original in KOP: 295g

New FIRST boulders (grey) recieved yesterday:
285g
285g
300g

Of much greater concern to our team is the remarkable increase in stiffness of all of the new balls. Our shooter compresses the ball, so the new stiffer balls slow the motors more and travel significantly less distance. We set up a jig to measure the force required to compress each ball to 8 inches. Results...

Original KOP Ball:
6,300g

New Balls:
11,860g
11,235g
12,890g

We don't know how much of this is due to the older ball being broken in, but we don't believe that it ever flew that poorly even when new. So is it an issue with differences in the foam from batch to batch or was the first ball just an outlier?

We will post a picture of how we measured the compression. If you can obtain data for your own boulders to compare, please post them as well.

Image: to be posted soon

[D_Price]

We have not bought any due to the pricing but I am curious as the fluctuation in weight.

[FYRERobot5480]

We are wondering about the diameter of the balls, having only 1 ball, we can't compare weights, but the manual says the ball is 10" diameter, but ours is measuring as 9 5/8th.

Anyone else noticed this? We are wondering if it has to do with our altitude, (almost 5000 ft) and how competing at lower altitude could affect our shooter if the size changes this much.

[Grim Tuesday]

This compression issue arose in 2012. Wise teams will design shooters that hit the target regardless of compression status.

[electroken]

Originally Posted by FYRERobot5480

We are wondering about the diameter of the balls, having only 1 ball, we can't compare weights, but the manual says the ball is 10" diameter, but ours is measuring as 9 5/8th.

Anyone else noticed this? We are wondering if it has to do with our altitude, (almost 5000 ft) and how competing at lower altitude could affect our shooter if the size changes this much.

The balls aren't sealed, or at least ours is not. It has one small (0.1" -ish) orifice in the outer covering, so I would not expect any difference in diameter due to changes in barometric pressure.

The ball that came in our KOP measures 9.7" in diameter at 300 feet above sea level and weighs 290g.

[The Doctor]

Originally Posted by FYRERobot5480

Anyone else noticed this? We are wondering if it has to do with our altitude, (almost 5000 ft) and how competing at lower altitude could affect our shooter if the size changes this much.

The surface is porous, so the boulders shouldn't necessarily change with altitude.

[evanperryg]

Originally Posted by FYRERobot5480

We are wondering about the diameter of the balls, having only 1 ball, we can't compare weights, but the manual says the ball is 10" diameter, but ours is measuring as 9 5/8th.

Anyone else noticed this? We are wondering if it has to do with our altitude, (almost 5000 ft) and how competing at lower altitude could affect our shooter if the size changes this much.

We noticed this as well, and we're at 577ft so I'm sure that's not it . We haven't dimensioned the two additional balls we purchased, but the KOP ball definitely comes in at a little less than 10." We haven't massed any of them, but if the humidity has to do with it, the balls should equalize over time. Those of you who have posted ball weights, if you are able to provide your shop's temperatures and humidity, I'd like to start organizing some of this data more nicely.

[Jcarbon]

When I massed our boulders today, they were quite consistent. We only have grey, FIRST branded balls from Andymark.

Original KOP boulder: 283.3g
Additional boulders from Andymark:
285.8g
286.6g
284.2g
285.5g