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Subject: 
Primitive tolerances
Newsgroups: 
lugnet.cad.dev
Date: 
Wed, 19 Nov 2003 19:23:35 GMT
Viewed: 
1467 times
  
Can someone tell me what kind of accuracy tolerances we should be working within
when it comes to scalable primitives?

http://www.ldraw.org/cgi-bin/ptdetail.cgi?f=p/48/4-4ring3.dat

I have placed a hold vote on this ring. Most all the numbers are within .0002.
Is that acceptable or should the numbers be corrected.  Can someone else give
this part a close look over?

dat file / prim-gen
.3916 ->  .3915
.5221 ->  .522
.7765 ->  .7764
1.0353 -> 1.0352
2.7716 -> 2.7717
2.8978 -> 2.8977
2.9743 -> 2.9742
3.6955 -> 3.6956
3.8637 -> 3.8636
3.9658 -> 3.9656
I stopped tracking numbers at this point. There may be more that vary.

I have been comparing this part to what "my" primitive generator says. I need to
know if my primitive generator is giving us the correct numbers or not.

Also see this thread for some reference information.
http://news.lugnet.com/cad/?n=10209

Paul



Message has 2 Replies:
  Re: Primitive tolerances
 
(...) My understanding was that primitives should have 4 decimal places of accuracy. However, whether or not this is the case, I think that any decimal places that are included should be accurate including appropriate rounding. Just my 2 cents. (...) (21 years ago, 20-Nov-03, to lugnet.cad.dev)
  Re: Primitive tolerances
 
(...) Generally parts only need to be authored to 3 decimal places. We decided on 4 DPs for the scalable primitives so that they could be scaled x10 without degrading the quality of the part. One could argue that p/48 primitves should be coded with (...) (21 years ago, 20-Nov-03, to lugnet.cad.dev)

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