3D sketch points 'flip' 180¦ randomly
3D sketch points 'flip' 180¦ randomly
(OP)
Hi,
I have a series of 3D sketch points (3DSketch4 in attached model), each of which is constrained by two 'on plane' constraints, and one 'on surface' constraint. The surface is an extruded ellipse (nearly cylindrical), which means the 3d points could mathematically be in one of two points.
Problem is, when scrolling through configurations where other geometry changes, the 3d points 'flip' 180° to the other side of the cylinder, causing the 'web' features in the model to fail.
If anyone cares to open the attached file, configurations 03 and 08 are correct, all the others show problems!
Any help appreciated
Simon
I have a series of 3D sketch points (3DSketch4 in attached model), each of which is constrained by two 'on plane' constraints, and one 'on surface' constraint. The surface is an extruded ellipse (nearly cylindrical), which means the 3d points could mathematically be in one of two points.
Problem is, when scrolling through configurations where other geometry changes, the 3d points 'flip' 180° to the other side of the cylinder, causing the 'web' features in the model to fail.
If anyone cares to open the attached file, configurations 03 and 08 are correct, all the others show problems!
Any help appreciated
Simon






RE: 3D sketch points 'flip' 180¦ randomly
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Hardie "Crashj" Johnson
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RE: 3D sketch points 'flip' 180¦ randomly
Below is a link to some more information about what and why it is what it is, and while it's not really anything which will help the 'victims' of this (i.e the CAD user), at least you'll know that it's a real issue and not something caused by cosmic rays or the fact that you your company refused to hire a 'feng shui' consultant when they last remodeled your office, although on second thought, particularly after reading the various articles on 'chirality' (like the one below), one comes to believe that perhaps applying a bit of 'feng shui' rules to software design just might help
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Good luck...
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RE: 3D sketch points 'flip' 180¦ randomly
Snowcrash, yes, "..confine the points to one side of the split" is exactly what I need to do. But there's no 'stay on this side of the right plane' constraint!
Yep, it's a 2012 version, and as you all know - I can't save backwards.
RE: 3D sketch points 'flip' 180¦ randomly
- - -Updraft
RE: 3D sketch points 'flip' 180¦ randomly
Thanks for the link
I had to scroll up for a moment because I thought I might have wandered from the SolidWorks forum. Did you read the post about Negative dimensions on SolidWorks? It referred to a method I used on UGv18 when 0 value dimensions weren't allowed
SolidWorks currently has problems with their swap direction on dimensions in that if you swap direction it shows a temporary minus value but then shows a positive value in a negative direction. If changed to zero and then given a value it swaps directions.
Does NX now support Negative Dims?
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RE: 3D sketch points 'flip' 180¦ randomly
For example, if I have a pair of parallel lines, the dimension constraining the distance between the two lines can be positive or negative, however the dimension constraining the overall length of either of the lines can only be positive.
Is that what you were asking about?
John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
http://www.siemens.com/plm
UG/NX Museum: http://www.plmworld.org/p/cm/ld/fid=209
To an Engineer, the glass is twice as big as it needs to be.
RE: 3D sketch points 'flip' 180¦ randomly
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RE: 3D sketch points 'flip' 180¦ randomly
If it helps anyone; in the end I conceded defeat, extruded all the ribs vertically upwards, then surface cut them with a revolved conical sheet as the trim plane. Not quite what I needed, but good enough for now.