Subject:
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Re: More studs in holes...
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Newsgroups:
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lugnet.build
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Date:
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Thu, 16 Dec 1999 03:10:59 GMT
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Viewed:
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784 times
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I almost fear suggesting our fearless leader might be mistaken, but what the
heck:
Todd Lehman <lehman@javanet.com> wrote in message
news:FMsIKp.BBJ@lugnet.com...
> ...so he doesn't actually make the claim that it wasn't intended. He just
> warns that the plastic may deform if left like this for long periods of • time.
>
> I just checked the grip on several batches of Technic beams laying around
> at home and none of them gripped studs any tighther than the tubes on the
> bottom of bricks grip studs or the square holes on the back of 1x1 bricks
> with recessed side studs[2] or 1x2x2 standing control units with 3 • studs[3]
> do.
>
> So if, in practice, studs actually become deformed from long sittings in
> such configurations, then it must be due to manufacturing errors rather • than
> design errors in the parts. LEGO wouldn't've goofed something like this • up
> in the design stage, and wouldn't've made the diameter of a peg exactly • the
> same diameter as a stud if it wasn't intended to work this way.
Well, they didn't. They designed an interference fit. And all interference
fits in plastic will demonstrate "creep" over time. It is generally
something like some small percentage of the initial strain (interference
distance), and is a function of 1,000 variables, including plastic type and
temperature, etc.
But NOTHING is so important as the geometry. The hoop-stress involved in
putting studs in holes is much different than the typical brick-to-brick
fit, which involves slight deformation of very carefully designed pieces of
the brick inside. Colloquially, it just feels different to put studs in
beam holes, and the fit, although it is there, is inferior to the more
standard stud connections.
By the way, many of the things you see in LEGO are there to precisely
control the interference fit of the studs. The funny cuts in gears come to
mind.
Frankly, I wouldn't worry about it, and I think Fred over-stated its
importance. I doubt you would really notice it unless you were running a
test that took a year or more.
[I used to design plastic for DEC. Remember them? It is rare to see better
plastic engineering than LEGO.]
--Jack Gregory
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