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Subject: What are the dimensions of a LEGO® brick?
Topic-Level: 1
Content-Language: en
Originator: Fred M. Sloniker, 1998-11-28
Revision: Robert M. Dye, 1999-11-20
Revision: Steve Bliss, 1999-11-30
Reference: http://www.lugnet.com/news/display.cgi?lugnet.general:853
Reference: http://www.lugnet.com/news/display.cgi?lugnet.general:933
Comment: Include metric and imperial measurments, as arguments for both
Location: /build/
<P><I>From Robert M. Dye:</I></P>
<P>
A 2x2 brick is 5 plates wide, so the aspect ratio is 1 (stud-to-stud)
to 2.5 (thickness of plates). Or, 1 (brick thickness) to 1.2
(stud-to-stud). Or, 1 (plate thickness) to 0.4 (stud-to-stud).
</P>
<P><I>From Steve Bliss:</I></P>
<P>
The basic ratio is 2:5, for stud-spacing to plate-height -- which is
why you see Technic models with beam-plate-plate-beam stacked up: this
allows beams to be placed vertically, and connected to the other
beams.
</P>
<P>
In LDU (LDraw units), the measurements are:
</P>
<P><PRE>
Brick height = 24
Plate height = 8
Stud pitch = 20
</PRE></P>
<P>
I believe the LU (LEGO Unit) measurements are:
</P>
<P><PRE>
Brick height = 6
Plate height = 2
Stud pitch = 5
</PRE></P>
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I have added the Metric and Imperial dimensions to the previous discussion of
ratios.
Subject: What are the dimensions and aspect ratios of LEGO® bricks?
Topic-Level: 1
Content-Language: en
Originator: Fred M. Sloniker, 1998-11-28
Revision: Robert M. Dye, 1999-11-20
Revision: Steve Bliss, 1999-11-30
Comment: The above two dates (1999-11-20 and 1999-11-30) are known to be wrong
Revision: Robert Munafo, 1999-07-22
Reference: http://www.lugnet.com/news/display.cgi?lugnet.general:853
Reference: http://www.lugnet.com/news/display.cgi?lugnet.general:933
Location: /build/
<P><I>From Robert M. Dye:</I></P>
<P>
A 2x2 brick is 5 plates wide, so the aspect ratio is 1 (stud-to-stud)
to 2.5 (thickness of plates). Or, 1 (brick thickness) to 1.2
(stud-to-stud). Or, 1 (plate thickness) to 0.4 (stud-to-stud).
</P>
<P><I>From Steve Bliss:</I></P>
<P>
The basic ratio is 2:5, for stud-spacing to plate-height -- which is
why you see Technic models with beam-plate-plate-beam stacked up: this
allows beams to be placed vertically, and connected to the other
beams.
</P>
<P>
In LDU (LDraw units), the measurements are:
</P>
<P><PRE>
Brick height = 24
Plate height = 8
Stud pitch = 20
</PRE></P>
<P>
I believe the LU (LEGO Unit) measurements are:
</P>
<P><PRE>
Brick height = 6
Plate height = 2
Stud pitch = 5
</PRE></P>
<P><I>From Robert Munafo:</I></P>
<P>
The actual dimension (rather than the ratios) can be determined by carefully
measuring a properly constructed "wall" of bricks. Vertical dimensions are
prone to error caused by sloppy stacking, but long horizontal walls constructed
from two or more layers of overlapping bricks are not prone to such error. A
wall of this type built from Technic beams made in the late 1990's shows that
the stud pitch distance is 7.986 millimeters, plus or minus 2 microns, when the
parts are at 25 degrees centigrade (77 degrees Farenheit).
</P>
<P>
It is also worthwhile to note that LEGO bricks are always made a little smaller
than this dimension would suggest. For example, the length of a 2x4 brick is a
little less than 4 times 7.986 millimeters. The length is diminished slightly
so that there will be a small gap when bricks are stacked next to each other.
This gap allows for dust, marred surfaces and other imperfections. If the gap
were not there the bricks would tend to push each other apart and the overall
construction would be less strong.
</P>
<P>
Using the ratios above and converting to imperial measurements yields the
following figures for all three dimensions:
</P>
<P><PRE>
Brick height 9.582 mm 0.37724 in
Plate height 3.194 mm 0.12575 in
Stud pitch 7.985 mm 0.31437 in
</PRE></P>
<P>
The following popular approximations are often used. Note that the Imperial
approximations are each about 1 percent smaller than the corresponding S.I.
(Metric) approximation:
</P>
<P><PRE>
S.I. Imperial
Brick height 9.6 mm = 48/5 mm 0.375 in = 3/8 in
Plate height 3.2 mm = 16/5 mm 0.125 in = 1/8 in
Stud pitch 8.0 mm 0.3125 in = 5/16 in
</PRE></P>
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I have added the notes on dimension relationships originally from Jef Poskan:
Subject: What are the dimensions and aspect ratios of LEGO® bricks?
Topic-Level: 1
Content-Language: en
Originator: Fred M. Sloniker, 1998-11-28
Revision: Robert M. Dye, 1999-11-20
Revision: Steve Bliss, 1999-11-30
Comment: The above two dates (1999-11-20 and 1999-11-30) are known to be wrong
Revision: Robert Munafo, 1999-07-22
Reference: http://www.lugnet.com/news/display.cgi?lugnet.general:853
Reference: http://www.lugnet.com/news/display.cgi?lugnet.general:933
Location: /build/
<P><I>From Robert M. Dye:</I></P>
<P>
A 2x2 brick is 5 plates wide, so the aspect ratio is 1 (stud-to-stud)
to 2.5 (thickness of plates). Or, 1 (brick thickness) to 1.2
(stud-to-stud). Or, 1 (plate thickness) to 0.4 (stud-to-stud).
</P>
<P><I>From Steve Bliss:</I></P>
<P>
The basic ratio is 2:5, for stud-spacing to plate-height -- which is
why you see Technic models with beam-plate-plate-beam stacked up: this
allows beams to be placed vertically, and connected to the other
beams.
</P>
<P>
In LDU (LDraw units), the measurements are:
</P>
<P><PRE>
Brick height = 24
Plate height = 8
Stud pitch = 20
</PRE></P>
<P>
I believe the LU (LEGO Unit) measurements are:
</P>
<P><PRE>
Brick height = 6
Plate height = 2
Stud pitch = 5
</PRE></P>
<P><I>From Jef Poskanzer (jef@netcom.com)</I></P>
<P>
Approximate dimensions in millimeters:
</P>
<PRE>
Spacing of stud centers: 8
Diameter of studs: 5
Height of block: 9.6
Height of studs: 1.7
Thickness of brick walls: 1.5
Outer diameter of cylinders
(found on underside of bricks): 6.31
Thickness of cylinder walls: 0.657
</PRE>
<P>
Formulas:
</P>
<P>
(height of brick) =
(spacing of stud centers) * 6 / 5
</P>
<P>
(thickness of brick walls) =
((spacing of stud centers) - (diameter of studs)) / 2
</P>
<P>
(height of studs) =
(height of brick) / 3 - (thickness of brick walls)
</P>
<P>
(outer diameter of cylinders) =
sqrt(2) * (spacing of stud centers) - (diameter of studs)
</P>
<P>
(thickness of cylinder walls) =
((outer diameter of cylinders) - (diameter of studs)) / 2
</P>
<P><I>From Robert Munafo:</I></P>
<P>
The actual dimension (rather than the ratios) can be determined by carefully
measuring a properly constructed "wall" of bricks. Vertical dimensions are
prone to error caused by sloppy stacking, but long horizontal walls constructed
from two or more layers of overlapping bricks are not prone to such error. A
wall of this type built from Technic beams made in the late 1990's shows that
the stud pitch distance is 7.986 millimeters, plus or minus 2 microns, when the
parts are at 25 degrees centigrade (77 degrees Farenheit).
</P>
<P>
It is also worthwhile to note that LEGO bricks are always made a little smaller
than this dimension would suggest. For example, the length of a 2x4 brick is a
little less than 4 times 7.986 millimeters. The length is diminished slightly
so that there will be a small gap when bricks are stacked next to each other.
This gap allows for dust, marred surfaces and other imperfections. If the gap
were not there the bricks would tend to push each other apart and the overall
construction would be less strong.
</P>
<P>
Using the ratios above and converting to imperial measurements yields the
following figures for all three dimensions:
</P>
<P><PRE>
Brick height 9.582 mm 0.37724 in
Plate height 3.194 mm 0.12575 in
Stud pitch 7.985 mm 0.31437 in
</PRE></P>
<P>
The following popular approximations are often used. Note that the Imperial
approximations are each about 1 percent smaller than the corresponding S.I.
(Metric) approximation:
</P>
<P><PRE>
S.I. Imperial
Brick height 9.6 mm = 48/5 mm 0.375 in = 3/8 in
Plate height 3.2 mm = 16/5 mm 0.125 in = 1/8 in
Stud pitch 8.0 mm 0.3125 in = 5/16 in
</PRE></P>
<P>
There seems to be no authoritative answer as to why the 5-to-6 ratio mentioned
above was chosen, rather than a more obvious 1-to-1. However, the answer
probably has to do with the size and shape of real-world bricks used to make
buildings. This makes sense since most early LEGO building sets were oriented
around the general idea of making buildings out of bricks.
</P>
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|
I have added a general conversion for mm to LD units.
Robert Munafo <munafo@gcctechNO.SPAMcom> wrote in message
news:FFwwJG.K90@lugnet.com...
> I have added the notes on dimension relationships originally from Jef • Poskan:
>
> Subject: What are the dimensions and aspect ratios of LEGO® bricks?
> Topic-Level: 1
> Content-Language: en
> Originator: Fred M. Sloniker, 1998-11-28
> Revision: Robert M. Dye, 1999-11-20
> Revision: Steve Bliss, 1999-11-30
> Comment: The above two dates (1999-11-20 and 1999-11-30) are known to be • wrong
> Revision: Robert Munafo, 1999-07-22
> Reference: http://www.lugnet.com/news/display.cgi?lugnet.general:853
> Reference: http://www.lugnet.com/news/display.cgi?lugnet.general:933
> Location: /build/
>
> <P><I>From Robert M. Dye:</I></P>
>
> <P>
> A 2x2 brick is 5 plates wide, so the aspect ratio is 1 (stud-to-stud)
> to 2.5 (thickness of plates). Or, 1 (brick thickness) to 1.2
> (stud-to-stud). Or, 1 (plate thickness) to 0.4 (stud-to-stud).
> </P>
>
>
> <P><I>From Steve Bliss:</I></P>
>
> <P>
> The basic ratio is 2:5, for stud-spacing to plate-height -- which is
> why you see Technic models with beam-plate-plate-beam stacked up: this
> allows beams to be placed vertically, and connected to the other
> beams.
> </P>
>
> <P>
> In LDU (LDraw units), the measurements are:
> </P>
>
> <P><PRE>
> Brick height = 24
> Plate height = 8
> Stud pitch = 20
> </PRE></P>
>
> <P>
> I believe the LU (LEGO Unit) measurements are:
> </P>
>
> <P><PRE>
> Brick height = 6
> Plate height = 2
> Stud pitch = 5
> </PRE></P>
>
>
> <P><I>From Jef Poskanzer (jef@netcom.com)</I></P>
>
> <P>
> Approximate dimensions in millimeters:
> </P>
>
> <PRE>
> Spacing of stud centers: 8
> Diameter of studs: 5
> Height of block: 9.6
> Height of studs: 1.7
> Thickness of brick walls: 1.5
> Outer diameter of cylinders
> (found on underside of bricks): 6.31
> Thickness of cylinder walls: 0.657
> </PRE>
>
> <P>
> Formulas:
> </P>
>
> <P>
> (height of brick) =
> (spacing of stud centers) * 6 / 5
> </P>
>
> <P>
> (thickness of brick walls) =
> ((spacing of stud centers) - (diameter of studs)) / 2
> </P>
>
> <P>
> (height of studs) =
> (height of brick) / 3 - (thickness of brick walls)
> </P>
>
> <P>
> (outer diameter of cylinders) =
> sqrt(2) * (spacing of stud centers) - (diameter of studs)
> </P>
>
> <P>
> (thickness of cylinder walls) =
> ((outer diameter of cylinders) - (diameter of studs)) / 2
> </P>
>
>
> <P><I>From Robert Munafo:</I></P>
>
> <P>
> The actual dimension (rather than the ratios) can be determined by • carefully
> measuring a properly constructed "wall" of bricks. Vertical dimensions are
> prone to error caused by sloppy stacking, but long horizontal walls • constructed
> from two or more layers of overlapping bricks are not prone to such error. • A
> wall of this type built from Technic beams made in the late 1990's shows • that
> the stud pitch distance is 7.986 millimeters, plus or minus 2 microns, • when the
> parts are at 25 degrees centigrade (77 degrees Farenheit).
> </P>
>
> <P>
> It is also worthwhile to note that LEGO bricks are always made a little • smaller
> than this dimension would suggest. For example, the length of a 2x4 brick • is a
> little less than 4 times 7.986 millimeters. The length is diminished • slightly
> so that there will be a small gap when bricks are stacked next to each • other.
> This gap allows for dust, marred surfaces and other imperfections. If the • gap
> were not there the bricks would tend to push each other apart and the • overall
> construction would be less strong.
> </P>
>
> <P>
> Using the ratios above and converting to imperial measurements yields the
> following figures for all three dimensions:
> </P>
>
> <P><PRE>
> Brick height 9.582 mm 0.37724 in
> Plate height 3.194 mm 0.12575 in
> Stud pitch 7.985 mm 0.31437 in
> </PRE></P>
>
> <P>
> The following popular approximations are often used. Note that the • Imperial
> approximations are each about 1 percent smaller than the corresponding • S.I.
> (Metric) approximation:
> </P>
>
> <P><PRE>
> S.I. Imperial
> Brick height 9.6 mm = 48/5 mm 0.375 in = 3/8 in
> Plate height 3.2 mm = 16/5 mm 0.125 in = 1/8 in
> Stud pitch 8.0 mm 0.3125 in = 5/16 in
> </PRE></P>
>
> <P>
> There seems to be no authoritative answer as to why the 5-to-6 ratio • mentioned
> above was chosen, rather than a more obvious 1-to-1. However, the answer
> probably has to do with the size and shape of real-world bricks used to • make
> buildings. This makes sense since most early LEGO building sets were • oriented
> around the general idea of making buildings out of bricks.
> </P>
A general conversion is 1mm = 2.66666666667LD units (The large number of 6's
reduces error). This conversion can be found from a brick wall thickness:
4LD = 1.5mm. Another source shows the lego brick wall thickness as 1.6mm
(making the conversion 1mm = 2.5LD units). For myself, to determine which
was more accurate, I used a caliper accurate to .001inches and measured the
thickness of ten walls from various parts. The measurements ranged between
0.062 and 0.058 inches or 1.5748mm to 1.4732mm. I decided the 1.5
approximation worked best (using the
1mm = 2.5LD units conversion looks nicer, but is less accurate for longer
measurements).
Note: This conversion should be used carefully and you must make sure the
part you are building conforms to existing brick dimensions. But for areas
that are not uniform or have odd curvatures and do not fit with any other
bricks, you can use the conversion above to estimate the correct dimensions.
Adam
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Adam Howard wrote:
> I have added a general conversion for mm to LD units.
> Robert Munafo <munafo@gcctechNO.SPAMcom> wrote in message
> news:FFwwJG.K90@lugnet.com...
> > I have added the notes on dimension relationships originally from Jef • Poskan:
> > Subject: What are the dimensions and aspect ratios of LEGO® bricks?
These are both great additions, thanks! :-,
Adam, do you have an inch <-> LDU conversion constant as well?
Cheers,
- jsproat
--
Jeremy H. Sproat <jsproat@io.com>
http://www.io.com/~jsproat
Darth Maul Lives
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Hi Sproat,
> These are both great additions, thanks! :-,
Thanks :)
> Adam, do you have an inch <-> LDU conversion constant as well?
No. I don't like to get the english system involved. But if someone needed one they could try converting 1mm= 2.66666666667LD to
english. When I do it I get 1 inch = 67.73333333334LD (Yuck). You could also look at using 4LD = 0.06 inches (1 inch =
66.66666666667LD). I haven't done any sampling/testing/comparing for that so I don't know how acurate it would be.
Thanks,
Adam
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In lugnet.faq, Jeremy Sproat writes:
> Adam, do you have an inch <-> LDU conversion constant as well?
Conversion constants are much more relevant to the stud pitch than the brick
height or width, because brick heights and widths are subject to the error
caused by the fact that LEGO always designs elements so there will be tiny gaps
when assembled, to make them fit better even when marred or dirty.
The stud pitch in LDU is given by Steve Bliss's section of the FAQ answer,
which says that the stud pitch is 20 LDU (LDraw units). That's an exact figure,
because of the LDU's role as a way to make it easier to position pieces at
integral stud-positions when you're building a model in LDraw.
The stud pitch in the physical world is (from my section of the FAQ answer)
7.986 millimeters plus or minus 2 microns. Expressed as a percentage the error
is 0.025 of a percent (or 1 in 4000).
The inch to millimeter conversion is (by international standard) exactly 25.4
millimeters to an inch. That is also an exact figure (by international
agreement).
When you do the math, you get the following conversion factors, each with its
corresponding error term:
1 LDU = 0.3993 +-0.0001 millimeters
1 millimeter = 2.5043 +- 0.0006 LDU
1 LDU = 0.015720 +- 0.000004 inches
1 inch = 63.611 +- 0.016 LDU
- Robert Munafo http://www.mrob.com/
LEGO: TC+++(8480) SW++ #+ S-- LS++ Hsp M+ A@ LM++ YB64m IC13
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Robert Munafo wrote:
> The inch to millimeter conversion is (by international standard) exactly 25.4
> millimeters to an inch. That is also an exact figure (by international
> agreement).
This surprises me. *Exactly* 25.4 mm / inch? I thought that the conversion
rate was kind of one of those irrational numbers (1) that had digits
trailing off into infinity or, failing that, Imelda Marcos' shoe closet.
:-,
> When you do the math, you get the following conversion factors, each with its
> corresponding error term:
> 1 LDU = 0.3993 +-0.0001 millimeters
> 1 millimeter = 2.5043 +- 0.0006 LDU
> 1 LDU = 0.015720 +- 0.000004 inches
> 1 inch = 63.611 +- 0.016 LDU
*This* is cool. Thanks for the table!
Cheers,
- jsproat
1. Arguably since we're converting between metric and an irrational
measurement system, but I digress. :-P
--
Jeremy H. Sproat <jsproat@io.com>
http://www.io.com/~jsproat
Darth Maul Lives
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In lugnet.faq, Jeremy Sproat writes:
> Robert Munafo wrote:
> > The inch to millimeter conversion is (by international standard) exactly • 25.4
> > millimeters to an inch. That is also an exact figure (by international
> > agreement).
>
> This surprises me. *Exactly* 25.4 mm / inch? I thought that the conversion
> rate was kind of one of those irrational numbers (1) that had digits
> trailing off into infinity or, failing that, Imelda Marcos' shoe closet.
Yes. Here is a table provided by Lycos:
http://infoplease.lycos.com/ipa/A0001729.html
scroll down and notice that the value for inch->millimeter is given as
"25.4000"
The story I heard is that, at some point around 100 years ago it was decided to
redefine the English weights and measures in terms of the SI (international
system or "metric") and when they looked at the units of length they discovered
that the inch was so close to being 25.4 millimeters that the error term in the
measurement of the inch (which had hitherto been defined by the length of a
rod) was greater than the difference they would impose by choosing a value of
exactly 2.54. So, the value of exactly 2.54 was chosen, much to the convenience
of scientists and schoolchildren everywhere.
Since then the meter has been redefined (twice, I believe) and the inch got
redefined right along with it.
- Robert Munafo http://www.mrob.com/
LEGO: TC+++(8480) SW++ #+ S-- LS++ Hsp M+ A@ LM++ YB64m IC13
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Sproaticus wrote:
>
> Robert Munafo wrote:
> > The inch to millimeter conversion is (by international standard) exactly 25.4
> > millimeters to an inch. That is also an exact figure (by international
> > agreement).
>
> This surprises me. *Exactly* 25.4 mm / inch? I thought that the conversion
> rate was kind of one of those irrational numbers (1) that had digits
> trailing off into infinity or, failing that, Imelda Marcos' shoe closet.
The inch was redefined some time ago to make it equal 2.54 centimeters
exactly.
It used to be slightly larger, but it was close enough that it didn't
really make
any difference when they changed it.
--
Tim Buchheim
| | | | | | | | | | | | | | | | | | | | | | |
On Wed, 25 Aug 1999 00:19:30 GMT, Timothy Carl Buchheim
<tcb@cs.hmcSPAM.edu> wrote:
> Sproaticus wrote:
> >
> > Robert Munafo wrote:
> > > The inch to millimeter conversion is (by international standard) exactly 25.4
> > > millimeters to an inch. That is also an exact figure (by international
> > > agreement).
> >
> > This surprises me. *Exactly* 25.4 mm / inch? I thought that the conversion
> > rate was kind of one of those irrational numbers (1) that had digits
> > trailing off into infinity or, failing that, Imelda Marcos' shoe closet.
>
>
> The inch was redefined some time ago to make it equal 2.54 centimeters
> exactly.
> It used to be slightly larger, but it was close enough that it didn't
> really make
> any difference when they changed it.
I *thought* I felt taller all of a sudden ...
Steve
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Supplement to conversion I added in:
Adam Howard <abhoward10@hotmail.com> wrote in message news:FG4FGJ.9Fn@lugnet.com...
> I have added a general conversion for mm to LD units.
>
> Robert Munafo <munafo@gcctechNO.SPAMcom> wrote in message
> news:FFwwJG.K90@lugnet.com...
> > I have added the notes on dimension relationships originally from Jef • Poskan:
> >
> > Subject: What are the dimensions and aspect ratios of LEGO® bricks?
> > Topic-Level: 1
> > Content-Language: en
> > Originator: Fred M. Sloniker, 1998-11-28
> > Revision: Robert M. Dye, 1999-11-20
> > Revision: Steve Bliss, 1999-11-30
> > Comment: The above two dates (1999-11-20 and 1999-11-30) are known to be • wrong
> > Revision: Robert Munafo, 1999-07-22
> > Reference: http://www.lugnet.com/news/display.cgi?lugnet.general:853
> > Reference: http://www.lugnet.com/news/display.cgi?lugnet.general:933
> > Location: /build/
> >
> > <P><I>From Robert M. Dye:</I></P>
> >
> > <P>
> > A 2x2 brick is 5 plates wide, so the aspect ratio is 1 (stud-to-stud)
> > to 2.5 (thickness of plates). Or, 1 (brick thickness) to 1.2
> > (stud-to-stud). Or, 1 (plate thickness) to 0.4 (stud-to-stud).
> > </P>
> >
> >
> > <P><I>From Steve Bliss:</I></P>
> >
> > <P>
> > The basic ratio is 2:5, for stud-spacing to plate-height -- which is
> > why you see Technic models with beam-plate-plate-beam stacked up: this
> > allows beams to be placed vertically, and connected to the other
> > beams.
> > </P>
> >
> > <P>
> > In LDU (LDraw units), the measurements are:
> > </P>
> >
> > <P><PRE>
> > Brick height = 24
> > Plate height = 8
> > Stud pitch = 20
> > </PRE></P>
> >
> > <P>
> > I believe the LU (LEGO Unit) measurements are:
> > </P>
> >
> > <P><PRE>
> > Brick height = 6
> > Plate height = 2
> > Stud pitch = 5
> > </PRE></P>
> >
> >
> > <P><I>From Jef Poskanzer (jef@netcom.com)</I></P>
> >
> > <P>
> > Approximate dimensions in millimeters:
> > </P>
> >
> > <PRE>
> > Spacing of stud centers: 8
> > Diameter of studs: 5
> > Height of block: 9.6
> > Height of studs: 1.7
> > Thickness of brick walls: 1.5
> > Outer diameter of cylinders
> > (found on underside of bricks): 6.31
> > Thickness of cylinder walls: 0.657
> > </PRE>
> >
> > <P>
> > Formulas:
> > </P>
> >
> > <P>
> > (height of brick) =
> > (spacing of stud centers) * 6 / 5
> > </P>
> >
> > <P>
> > (thickness of brick walls) =
> > ((spacing of stud centers) - (diameter of studs)) / 2
> > </P>
> >
> > <P>
> > (height of studs) =
> > (height of brick) / 3 - (thickness of brick walls)
> > </P>
> >
> > <P>
> > (outer diameter of cylinders) =
> > sqrt(2) * (spacing of stud centers) - (diameter of studs)
> > </P>
> >
> > <P>
> > (thickness of cylinder walls) =
> > ((outer diameter of cylinders) - (diameter of studs)) / 2
> > </P>
> >
> >
> > <P><I>From Robert Munafo:</I></P>
> >
> > <P>
> > The actual dimension (rather than the ratios) can be determined by • carefully
> > measuring a properly constructed "wall" of bricks. Vertical dimensions are
> > prone to error caused by sloppy stacking, but long horizontal walls • constructed
> > from two or more layers of overlapping bricks are not prone to such error. • A
> > wall of this type built from Technic beams made in the late 1990's shows • that
> > the stud pitch distance is 7.986 millimeters, plus or minus 2 microns, • when the
> > parts are at 25 degrees centigrade (77 degrees Farenheit).
> > </P>
> >
> > <P>
> > It is also worthwhile to note that LEGO bricks are always made a little • smaller
> > than this dimension would suggest. For example, the length of a 2x4 brick • is a
> > little less than 4 times 7.986 millimeters. The length is diminished • slightly
> > so that there will be a small gap when bricks are stacked next to each • other.
> > This gap allows for dust, marred surfaces and other imperfections. If the • gap
> > were not there the bricks would tend to push each other apart and the • overall
> > construction would be less strong.
> > </P>
> >
> > <P>
> > Using the ratios above and converting to imperial measurements yields the
> > following figures for all three dimensions:
> > </P>
> >
> > <P><PRE>
> > Brick height 9.582 mm 0.37724 in
> > Plate height 3.194 mm 0.12575 in
> > Stud pitch 7.985 mm 0.31437 in
> > </PRE></P>
> >
> > <P>
> > The following popular approximations are often used. Note that the • Imperial
> > approximations are each about 1 percent smaller than the corresponding • S.I.
> > (Metric) approximation:
> > </P>
> >
> > <P><PRE>
> > S.I. Imperial
> > Brick height 9.6 mm = 48/5 mm 0.375 in = 3/8 in
> > Plate height 3.2 mm = 16/5 mm 0.125 in = 1/8 in
> > Stud pitch 8.0 mm 0.3125 in = 5/16 in
> > </PRE></P>
> >
> > <P>
> > There seems to be no authoritative answer as to why the 5-to-6 ratio • mentioned
> > above was chosen, rather than a more obvious 1-to-1. However, the answer
> > probably has to do with the size and shape of real-world bricks used to • make
> > buildings. This makes sense since most early LEGO building sets were • oriented
> > around the general idea of making buildings out of bricks.
> > </P>
>
> A general conversion is 1mm = 2.66666666667LD units (The large number of 6's
> reduces error). This conversion can be found from a brick wall thickness:
> 4LD = 1.5mm. Another source shows the lego brick wall thickness as 1.6mm
> (making the conversion 1mm = 2.5LD units). For myself, to determine which
> was more accurate, I used a caliper accurate to .001inches and measured the
> thickness of ten walls from various parts. The measurements ranged between
> 0.062 and 0.058 inches or 1.5748mm to 1.4732mm. I decided the 1.5
> approximation worked best (using the
> 1mm = 2.5LD units conversion looks nicer, but is less accurate for longer
> measurements).
> Note: This conversion should be used carefully and you must make sure the
> part you are building conforms to existing brick dimensions. But for areas
> that are not uniform or have odd curvatures and do not fit with any other
> bricks, you can use the conversion above to estimate the correct dimensions.
> Adam
After taking some more samples I have decided I need to take a lot more. So far I've measured about 20 parts varying in size from a
2x2x1 to a 1x6x1 as well as odd parts like a horse's hooves. What I have found is contrary to my original conversion and seems to
support the 1mm=2.5LD units more, but not quite. Here is what I've found lately:
1in = 64LD
1mm = 2.51968503937LD
I used two calipers to take the measurements. One only measures in inches and is accurate to 1/1000". The other measures both mm
and inches and is accurate to 1/20mm and 1/1000". Essentially I took a number of measurements to find a number of conversion
factors. Then choose a number of random LD brick dimension and converted them to mm and inches using each of the conversions. Then
I measured the brick dimensions with both of my calipers and looked to see which conversion matched best at each of the random
dimensions chosen. This showed me that the 1mm = 2.667LD was off slightly for very large LD (>120), and that the 1mm = 2.5LD was
also off. However, using 1mm = 2.51968503937 or 1in = 64LD seemed to provide consistent results. But, I still don't believe this
is accurate enough. I think we ought to start a statistical repository of brick dimensions. Then once we have- ohh say 1000 or so
we can start running them through the statistical mill to determine a good conversion factor.
This message does contain new info for the FAQ, but any further discussion should probably be moved to lugnet.cad or lugnet.cad.dev.
I don't have that nifty Follow-Up to field so please make sure you edit the newsgroup field when replying.
Thanks,
Adam
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