Subject:
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Re: Lego Brick Dimensions Changes?
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Newsgroups:
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lugnet.cad
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Date:
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Tue, 26 Nov 2002 20:09:43 GMT
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Viewed:
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799 times
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In lugnet.cad, Tony Hafner writes:
> LDraw also uses simplified geometry to make it easier to deal with. The two
> most obvious examples are stud height and bottom tube outside diameter.... simple geometry tells us that there's no way the
> outside of a bottom stud works out to an even number. What should these
> numbers really be?
This is one prime number relationship in the system. If cell spacing is 20
and stud radius is 6, then a diagonal distance between two studs is 20 *
Sqrt(2) - 12, or about 16.28. This is the tube outside diameter. The inside
diameter ought to be 12, which would give a tube wall thickness of
(16.28-12)/2 or 2.14.* Most wall thicknesses are 2.** Looking at a real Lego
brick shows that the tube is a kind of wavy wall which contacts the real
stud in 4 points.
The LDRAW unit, in terms of real Lego, is just over 1/64 inch, or preferably
metric at 0.40 mm, so that the cell spacing is 5/16 inch, or 8mm. The
difference between the English and Metric estimates is smaller than what you
can find with hand tools, given that real Lego has interesting variances as
well (it's smaller than the ideal measurements to make gaps between pieces.)
We became convinced of the metric basis by measurements on baseplates and
such. Anecdotal history says that Lego first substituted metric for English
units when they copied the 1940 Kiddicraft brick (a tubeless brick with
round studs.)
* Some clones like Intelliblocks use this naive measurement, others use the
wavy wall.
** A modification to the wall thickness may occur when a square rib of about
1/100" thickness inside the brick
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Message is in Reply To:
 | | Re: Lego Brick Dimensions Changes?
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| The LDraw standards for dimensions make up a self-consistent system, though that system has some fundamental differences when compared to real-world bricks. (...) The general rule is that a plate is 1/8th of an inch, so one ldraw unit is 1/64th of (...) (22 years ago, 26-Nov-02, to lugnet.cad)
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