accuracy

[roadrebel]

We've a huge problem of accuracy in here. We are modeling building structure with archs with all bolts and nuts. The problem is when we want to extend our structure up to 150ft, some pieces lose their reference because of the accuracy. Somebody have a bright idea ??


erik

 

[dlongmi]

Erik,


You are probably stretching something away from it's placement either explicitly or implicily through an assembly feature relative to a bounding box issue. In essence you may have a relative accuracy issue with parts created in the assembly. Check the parts in question for the bounding box size and remove any refs that increase it larger than needed.


Hope it helps.

 

[mmead0ws]

For performance reasons, Pro/ENGINEER uses Relative Accuracy by default (.0012). Absolute accuracy is calculated by multiplying relative accuracy by the lenght of the bounding box diagonal for the part. That means absolute accuracy changes as the model size changes.The bounding box diagonal lenght can be determined by selecting info > model size. Here is an indeptharticle about Pro/ENGINEER accuracy: http://www.eern.com/proe/tips/accuracy/index.htm


You can also set your accuracy to absolute. It will take a little longer to regenerate depending on how tight you set your accuracy, but it should eliminate the accuracy related failures.


Set the following config.pro options:
<UL>
<LI>enable_absolute_accuracy yes</LI>
<LI>enable_assembly_accuracy yes</LI>
<LI>accuracy_lower_bound should be at leastone decimal point tighter than your tightest tolerance (i.e. tol=.125, acc=.0001).</LI>
<LI>default_absolute_accuracyshould be tighter than your tightest tolerance (i.e. tol=.125, acc=.001).</LI>[/list]


If you set this for existing components, you might get geometry failures due to rounding discrepencies. Definitely set absolute accuracy for your template parts and assemblies for future use.


Good Luck