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 CAD / Development / 9338
9337  |  9339
Subject: 
Re: Primitive tolerances
Newsgroups: 
lugnet.cad.dev
Date: 
Thu, 20 Nov 2003 15:47:49 GMT
Viewed: 
1813 times
  
In lugnet.cad.dev, Paul Easter wrote:
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

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 more DPs since they
might be scaled more than x10.

So I would recommend that they do use 4 DPs, and use the algorithm that
multiplies the already rounded value from p/48/1-4disc,.

Chris



Message is in Reply To:
  Primitive tolerances
 
Can someone tell me what kind of accuracy tolerances we should be working within when it comes to scalable primitives? (URL) have placed a hold vote on this ring. Most all the numbers are within .0002. Is that acceptable or should the numbers be (...) (21 years ago, 19-Nov-03, to lugnet.cad.dev)

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