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4707  |  4709
Subject: 
Re: Modelling !
Newsgroups: 
lugnet.cad.dev
Date: 
Fri, 9 Jun 2000 19:15:13 GMT
Viewed: 
585 times
  
In lugnet.cad.dev, Rui Martins wrote:

Has some of you may remember, I have modelled the super car (8880) wheels and
tires, but when I modeled it I used Metric measurements (millimeters).

I would Like to know if there is an approved standard for a convertion ratio,
between millimeters and Ldraw units ?
So that I can scale the modelled parts and have them corrected!

I believe the conversion is 0.4mm = 1 LDU.  At least, that's what I always
use.

I would also like to know when are we going to define orientation standards /
guidelines for when a part is created ?

Standards are already there.  They just aren't strictly enforced.  As I see
it, there are two basic "orientation rules":

1. Do the same thing as other, similar parts which were previously modeled.
2. If there is inconsistency in the existing parts library, go with the
majority or the senior parts.

If a part truly breaks new ground, and there aren't any sufficiently
similar parts, then go with the following guidelines:

1. If the part is symmetric along both horizontal dimensions, the wider
dimension should go along the X-axis.
2. If the part is asymmetric along one horizontal dimension, that dimension
should go along the Z-axis, with the front/tip of the part pointed toward
Z-.
3. Center the part on X-Z.
4. Generally, put the top of part (not including studs) at Y=0.
5. Rotating parts *may* be centered on the point of rotation.

Since I have seen technic Axels(non-threaded/threaded), wheels, Wind Screens,
Windows, doors, etc...  with non matching orientations.
(example: Two wheels which have different rotation axis)
suppose you had diferent orientations for different bricks, that would be a
mess, so Why did this happen for the parts I mentioned before ?

Because we're all volunteers.

P.S. I know it is a huge task if we ever need to make all these parts have the
same orientation. We would probably have to make a program to correct our dat
files, when the parts were reoriented. Sigh..

Interesting thought.  If the program was programmed with all the version
information of the parts (using the 0 Official L-CAD Update XXXXXXX line),
it could be done.

Steve



Message has 2 Replies:
  Re: Modelling !
 
(...) Thanks ! So, 1.00 mm = 2.5 LDU (...) I call this common sence, which I think everyone should use ! (...) Are these your opinions only, or is assumed buy other people too ? I agree with most of it ! (...) Check! (...) Check! (...) Shouldn't we (...) (24 years ago, 9-Jun-00, to lugnet.cad.dev)
  Re: Modelling !
 
(...) This is only an approximation. The LEGO bricks are not metric -- The dimensions are based on inches. The width of one brick is 5/16 inch and the height (without studs) is 6/16 inch. So 0.39370mm = 1LDU is more precise. I normally try to (...) (24 years ago, 10-Jun-00, to lugnet.cad.dev)

Message is in Reply To:
  Modelling !
 
Has some of you may remember, I have modelled the super car (8880) wheels and tires, but when I modeled it I used Metric measurements (millimeters). I would Like to know if there is an approved standard for a convertion ratio, between millimeters (...) (24 years ago, 9-Jun-00, to lugnet.cad.dev)

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