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assembly rebuilds

Question asked by Joe Perushek on Apr 16, 2007
Latest reply on Apr 17, 2007 by Anna Wood

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Has anyone had problems with SW rebuilding a model (the samemodel)within an assembly 6 times or more in a row before it finallyfinishes? What about SW ALWAYS rebuilding the model from thebeginning (not in assy mode) irregardless of what was changed inthe feature tree?

I thought one of the earlier releases (2001-2002?) change therebuild code that the model would only rebuild the feature affectedby a change. Was this implemented? If so, is theresomething I need to turn on to get this feature?

I've literally got 3 full days of down time waiting for a modelI've been working on for the past week. A rebuild on thisthing (irregardless of the change) takes 15-20 minutes as itsrebuilding the file so many times.

Is there anyway to shut down assembly rebuilding? Unfortunately, I need to work in the assembly to create thegeometry around some parts. I've tried rebooting thecomputer, restarting SW, etc, etc etc.

I'm running XPpro SP2, SW SP3, a gig of ram (probably a little low,but that's what I've got) and a 3.0 HT intel.

Sorry, partially venting here. I'm really close to chuckingthe whole works into the lake and finishing up my design work witha stone tablet and chisel. It would be faster.

Any help is greatly appreciated. Thanks
Joe

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Steve Hutchison Apr 16, 2007 8:22 PM
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You don't mention what type of complexity/number of components/top level mates you are dealing with here.

I have found the following may contribute to long rebuild times on complex assemblies:
1. In-context relationships
2. Large number of top level mates.
3. Multiple configurations, especially when said configurations are represented in an open drawing file.

Solidworks allows you to achieve the same results many different ways. It is sometimes possible to paint yourself in a corner. I have quite a bit of experience in that area myself.
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Devon Sowell Apr 16, 2007 8:27 PM
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Hello Joe-

Look at the attached .jpg, System Options, Performance. Set the Assembly rebuild to Never.

Also I recommend using the Task Scheduler to "Update Files" or "Update Associated Files", which ever is appropriate. Run this unattended, after hours and you'll be amazed how fast the top level assembly will open after this function.

Good luck.
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- Never.JPG74.5 KB
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John Burrill Apr 16, 2007 8:51 PM
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Cyclical rebuilds usually indicate one or more of these conditions:
1)equations where the dependant variable occurs before the independant variable (the equation says your cube is twice as wide as it is high, so the extrude has to be completely solved before it's parent sketch can be updated. It's easy to get sloppy, especially when you're rearranging fetaures.
2) Circular external references: part A extrudes up to a face on part b and part b extrudes upto that face on part A.
3)massive ammounts of in-context features.
4)externally linked design tables
5)assembly cuts that include underconstrained parts in their feature scope.
6)in-context relationships that include underconstrained parts.
suggestions:
1, 2)
For the first two, the answer is, don't do that. If you're sizing a plate based on the number of cuts in it, don't link the base sketch dimension to the instance count on your linear pattern. Instead make an instance count variable in the equation editor and link both the equation and the instance to that to it. If your assembly relationships need to be that fluid between components, use an assembly sketch and reference planes to define common features
3) If you have lot's of in-context fetaures, lock them-after you've switched back to editing the assembly level and rebuilt.
4) I got so sick of Solidworks prompting me that the Excel file had changed, did I want to update the model, the drawing changed, did I want to update the design table. The design table changed, did I want to update the excel spread sheet? Hey, they're a wicked concept, but I get a lot more done manually synching those tables to my masters using edit definition.
5) fully constrain assembly feature sketches to moving components and make sure the sketches are mounted on the part, not on on a parallel face or plane.
6) There's little advantage in a hole that follows a bolt you drag around. Fully define the location of the bolt before you create top-down relationshps to it in another part.
Anywaty, that's my short list.
You might also tell us what version of Solidworks you're using and whether you're using lightweight parts.
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- Joe Perushek @ John Burrill on Apr 16, 2007 10:13 PM
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  Thanks for the responses Guys -
  
  I don't have a signature, but I mentioned in my original post I wasusing SW7, sp3.
  
  John,
  How do I go about locking in-context features, and can they beunlocked afterwards? I don't have any equations or anythinglike that, so hopefully locking the in-context stuff will help.
  
  I did have one surface that had a rebuilt time of almost 2 minutes(for whatever reason) which I build a different way and has helpedconsiderably. I'm down now to a total rebuild time of about1:15 now. A total rebuilt time of a couple of minutes isn't bad forsome of the weird stuff I'm working on, it the circular rebuildsthat are driving me nuts 1:15 X 6 rebuilds = lots of time... Uhg.
  
  thanks for the help
  Joe
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  - Devon Sowell @ Joe Perushek on Apr 16, 2007 10:48 PM
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    Hello Joe-
    
    John's post is excellent.
    
    Here is one more System Options setting that can help.
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    CHANGED-ONLY.JPG63.4 KB
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  - Anna Wood @ Joe Perushek on Apr 17, 2007 3:38 AM
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    Joe,
    
    John's list is excellent and good advice. By your saying the model is needing to cycle multiple times to complete a rebuild tells me that you most likely have some circular references in your model. That is the first place I would be looking if I was trouble shooting your model.
    
    You may want to go over to the SolidMap website at www.solidmap.com and download the free trial of their SolidMap software. The software gives a graphical representation of the interdependencies between features and parts. This may help you trouble shoot your model.
    
    Regards,
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