High Density Plastic Pellets for Making Beanbags
I'm intrigued by the GBallz E8 Pro description:
Pro filling is a mixture of 2 plastics to get the weight/volume just perfect
I expect one of those fillings is something like polypropylene, maybe the highish density stuff. The highest density PP filling I could find was 11 ounces/cup (#MuricaUnits), about 1.3 g/cm^3. I have two questions for the all-knowing Edge consciousness:
1 - Do you know of any plastic pellets that have a greater bulk density than 1.3 g/cm^3?
2 - Do you know why E8 Pros don't have their fillings separate by density?
Wouldn't a regularly spinning bean bag act like a centifruge causing the different density pellets to separate over time?
In practice I don't think this would be much of a problem, unless you really made an effort to spin the balls - and even then I suspect it would not be noticeable. My mate used to make some juggling balls (gballz-style) and we experimented with using millet and 1mm steel shot to customise the density and weight. In general it was really successful; you could get a nice small saggy ball that was still nicely weighted for numbers juggling, and I think the potential advantages are pretty good if done well.
The general randomness of throwing distributes the different densities around inside the ball and you don't notice the dual filling at all. It is much less of an issue than switching to Russian balls where it can be really noticeable that the centre-of-gravity is not the centre of the ball.
Not sure what the different densities of plastic might be, but I suspect this might be a better option than using the more dense steel shot. We never tested the balls to destruction but my feeling would be that the density of the steel shot would wear through the fabric more quickly and might start falling out. This could be more of a problem than with just different plastic pellets of more similar density.
Interesting, I'm surprised and impressed that even materials with such dramatically densities didn't settles meaningfully in authentic testing! Thanks.
I think in our case it was helped by the fact that the steel shot is particularly dense (almost certainly more so than any plastic pellets). You therefore only needed something like 1/10th-1/5th the volume (maybe a teaspoon or two) of shot to millet to make a big difference to the weight of the ball. With such a relatively small quantity of denser filling it didn't seem to clump much and is quickly redistributed after every throw.
Size of pellets is probably also important. I can imagine that, as the size of pellet increases, any internal distribution effects might be made more noticeable. It would be interesting to do more experimentation, and indeed to try the E8 balls.
I realise that this makes the business model more tricky but I am slightly disappointed that GBallz don't let you customise the weight/size ratio, given that they offer the different fillings. To me this was the main reason for using dual filling, you could get a proper sag without the ball being either massive or too lightweight. By just specifying the weight and size as a single option it seems to negate much of the potential of the product. What if I want a 2.5inch ball that weighs 115g but is still saggy for example?
"I realise that this makes the business model more tricky but I am slightly disappointed that GBallz don't let you customise the weight/size ratio, given that they offer the different fillings."
Preach. That's exactly the reason I'm looking into this.
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