Holes in ball-joints

[anothergol]

Recent (large) ball-joint balls have 6 holes in them, while old ones don't have any, anyone knows why?

Friction seems very random with those joints (& it matters - you want more fiction for legs & less for arms, for ex), and I thought it may have to do with the holes, but not really.

I can imagine those balls being used for snapping, but I'm not aware of any ball-joint part with matching bumps for rachetting, anyone knows?

[AmperZand]

I put Flinx's Ultimate Phoenix last night and was wondering the same thing. I don't know the answer, but it may have something to do with the manufacturing process or some future functionality when used with an as yet unreleased socket. But I'm just guessing.

[Zerobricks]

To save on plastic...

[GallardoLU]

To save on plastic...

^ correct answer, every gram of plastic maters in processing costs, (I work on the mold maker side of things) and our primary task is to give the customer a mold that looks and functions as they want but uses the very lowest abount of plastic possible. your standard Dairy Milk Gallon can be as light as 38grams! yet holds 8.5lbs of fluids. (deformation is allowed on those bottles )

[anothergol]

really?

Seriously, what % is the price of plastic, in the final cost of a brick? I would have expected it very, very, very low, waaaaay less than marketing, design, molds, etc.

So, 3 tiny holes in a ball, saving maybe 1% of an already very low price, I wouldn't believe in that. It's not like making something hollow to save 80% of plastic, here. In fact, it probably costed more in new molds.

[RTZX9R]

really?

Seriously, what % is the price of plastic, in the final cost of a brick? I would have expected it very, very, very low, waaaaay less than marketing, design, molds, etc.

So, 3 tiny holes in a ball, saving maybe 1% of an already very low price, I wouldn't believe in that. It's not like making something hollow to save 80% of plastic, here. In fact, it probably costed more in new molds.

Most types of manufacturing are happy to save even just 1%.. as it will be spread across millions of bricks which adds up!! These types of changes in any type of production are commonplace and are typically made when there is a net decrease in cost and no impact to the product function / performance.

[GallardoLU]

Also don't forget that every mold has a lifespan, when that is used up you need to buy new molds anyway, most of the time its just the same mold again, but when you can save 1% more plastic in the mold change you take it. my example in the milk bottle continued, most production machines making the gallon bottle are 6 or 8 head machines making a set of bottles every 7 seconds. so assuming its 8, at 7 seconds and you can save 1% more plastic each bottle (.38 grams in this case) in 1 set you save 3.04 grams, in the first minute you save 26.05grams (nearly 1 whole bottle) and the first hour...1563.4 grams (~3.5lbs an hour saved) that's just 1 machine in 1 hour. Lego is likely running more than 1 machine for these parts and making around 20-50 of them per machine cycle.

[HawkLord]

Save on plastic and maybe allow for a slight amount of flexibility with the ball.

[anothergol]

I think there are many bricks that would benefit from plastic-saving then, like every hollow part that's filled in places, preventing bars or axles to fully pass through them

[Vorkosigan]

Those filled in places are on purpose, either for structure or to stop the part from sliding all the way for a certain construction type.

[anothergol]

Those filled in places are on purpose, either for structure or to stop the part from sliding all the way for a certain construction type.

If I take a part like 32174, the longest axle hole is blocked, and I can well understand that it's to make it easier for kids, yet it's bloody annoying in practice, considering there is no 1.5 axle.

Still, that same piece has 3 different designs, would have been nice to have a non-blocked one. In the LDD, it's even working as hollow, actually!

..but what's the reason for a 30367 to be blocked? Can't think of any use. There is no blocked 3062 and no one would see a use for that.

Worse, I often see 30367 sold as "blocked or hollow" at BL. I'm not sure what that means exactly, maybe hollow means the X cross instead of the plain filling, because I've never seen a true hollow 30367.

Talking about this "hollow, but x-crossed blocked", this one had a purpose btw and it was anti-choking, not to save plastic.

Edited March 31, 2015 by anothergol

[weavil]

They would need to save cost considering they reintroduced Bionicle.

[Lyichir]

I doubt it has anything to do with cost (that might be a minor and pleasant side-effect, but nothing more). As a long-term Bionicle fan, I wager the most likely reason is to allow the ball itself to have a little bit of space to "compress" when a ball cup is attached.

Some context: ball joints of this sort have always been high-stress connections, with some level of fragility. In 2007, a batch of lime green ball cups was cooled improperly (or at least, that's the official answer, which doesn't sound that unreasonable), resulting in many of that year's Bionicle sets including ridiculously fragile ball cups. Lego redesigned the ball cups on all parts in 2008 (possibly to allow better grip over time), but that only magnified the issue, and the issue became associated with the overwrought specter of "cheap Chinese plastic" (despite most of the parts in question originating from other countries).

In 2011, the entire "Bionicle" building system was revamped with a new system that debuted in that year's Hero Factory sets. The new system was designed for versatility, but also durability. The new ball cups had thicker side supports, and the ball joints themselves had three holes in either side. And we received guarantees from numerous Lego employees that this would finally fix the issue, and the new joints should not ever break through normal use. Four years later, apart from a few isolated cases involving environmental factors, this seems to have been the case.

It's possible that the holes in the parts were intended to offset the additional plastic needed for the thicker ball cup supports, but given the nature of the rest of the changes made that year, it's not improbable that they were also intended to help relieve stress on the parts. Ball cup connections, unlike typical stud and tube connections and to a greater extent than even Technic pins, require the ball cup to flex out of shape slightly to "wrap around" the ball joint. Anything at all that could help to lessen that stress would extend the lifespan of the parts in question. But the ball cup can only be modified so much—so a change to the ball joint itself could be considered necessary. Holes in the ball joint presumably allow the joint itself a bit more flexibility—turning stress that would otherwise risk snapping a ball cup inwards on the ball itself, so that the risk of snapping is reduced.

[anothergol]

Interesting, makes sense, even though the balls seem to be made in hard ABS that may not compress thanks to 3 small holes.

I've collected a couple of those old "thinner" ball cups btw, because they, well, look better for arms.

I've also noticed that some of the balls had a more gritty, not shiny texture to them, and thought that it was made to help getting more friction with less clamp? I don't know..

I understand that they wouldn't do this because of the costs, but if balls had a rubber coating, they would compress well and keep friction over time (but maybe also dry out over years?).

Ah wait, I know where I've seen coated ball-joints - in some crappy kre-o set. Funny, I just checked them, and the cups have printed their shape on the balls. This said, they work quite well!