Re:Lego Saturn V
by vidarh on Wednesday May 03, 2017 @01:19PM
(#14257910)
One of my favourite examples is the black vs grey pins. Here's the black one [1], and [2] is the grey one. It's one of those parts that often look like it's a rather haphazard choice which one to use. And sometimes it might be.
But the black one has friction ridges that are a tiny fraction of a millimetre. Little enough that for constructions where friction doesn't matter (you just want to connect two parts and something else will prevent rotation), they are mostly interchangeable, but the grey ones work better to connect wheels that you actually want to be able to spin, and the black one works better if you want to build a rigid structure.
You don't tend to find two parts that similar with that kind of minor difference for most non-lego plastic building blocks because most of them don't manufacture their parts precisely enough for it to work.
But the black one has friction ridges that are a tiny fraction of a millimetre. Little enough that for constructions where friction doesn't matter (you just want to connect two parts and something else will prevent rotation), they are mostly interchangeable, but the grey ones work better to connect wheels that you actually want to be able to spin, and the black one works better if you want to build a rigid structure.
You don't tend to find two parts that similar with that kind of minor difference for most non-lego plastic building blocks because most of them don't manufacture their parts precisely enough for it to work.
[1] https://www.bricklink.com/v2/catalog/catalogitem.page?P=2780...
[2] https://www.bricklink.com/v2/catalog/catalogitem.page?P=3673...