×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

top-down design in SW2008

top-down design in SW2008

top-down design in SW2008

(OP)
I am working on some fixture design and thought it would be a good candidate for a top-down approach, as the fixture is dependent on several external constraints, some of which are not fully defined at the moment. I have read through the help on layout sketches, but am not entirely clear on their use in practice.

Does anyone have a sample assembly or some "best practice" tips so I don't inadvertently make my life difficult a few months down the road?

Thanks,
Matt

RE: top-down design in SW2008

Matt,
We have pretty much stopped using top down design. The Engineers here have a hard time with understanding it. So I use top down design to design my projects then delete before giving to Engineer for look – see.

I would suggest:

1. Keep it simple.
2. Do not locate edges. (Just to be safe)
3. Have the relationships only one (1) level deep.
4. Check your work into PDM every night.

Bradley
SolidWorks Pro 2008 x64 SP3.0
PDMWorks Workgroup, Dell XPS Intel(R) Pentium(R) D CPU
3.00 GHz, 5 GB RAM, Virtual memory 12577 MB, nVidia 3400
e-mail is Lotus Notes

RE: top-down design in SW2008

Have you worked through the Blocks tutorial?

cheers

RE: top-down design in SW2008

(OP)
Bradley, thanks for the tips.

CBL, I haven't. *Hangs head* I didn't realize that's what blocks were for. I'll do that now and see what I can learn.

RE: top-down design in SW2008

Some points to give you.
1.  Relate to sketches whenever possible.
2.  Use incontext relationships sparingly, only when necessary.
3.  Avoid using the "inplace" mate.  First mate a part in using planes or non-changing geometry.  Then generate the incontext relationships.  The "inplace" mate is automatically created if you "insert new part" into an assembly.
4.  Try to have all of your incontext parts driven by a single part as high up in the assembly tree as possible.  Preferably the first part in.  Avoid having a part near the top of the tree driven by a part below it in the tree.  This is known as a circular reference and greatly increases rebuild times and often results in the green rebuild light never going away.

-Dustin
Professional Engineer
Certified SolidWorks Professional

RE: top-down design in SW2008

Hi, Dustin:

Your following comment is questionable.  

***************************************
4.  Try to have all of your incontext parts driven by a single part as high up in the assembly tree as possible.  Preferably the first part in.  Avoid having a part near the top of the tree driven by a part below it in the tree.  This is known as a circular reference and greatly increases rebuild times and often results in the green rebuild light never going away.
***************************************

Part models in an assembly document are records in the assembly database.  The sequence of the parts in the assembly does not have anything to do with assembly performance.

Alex

RE: top-down design in SW2008

Quote:

Part models in an assembly document are records in the assembly database.  The sequence of the parts in the assembly does not have anything to do with assembly performance.

Well yes and no.  Performance will be affected if the assembly needs to loop through the tree multiple times to solve all the mates.

Here is a quote from Matt Lombard's SolidWorks Bible (pg. 491):

Quote:

The Assembly Feature Manager is solved in this order, or an order that is very similar:
1.  Solve reference geometry and sketches that are listed before parts in order, at the top of the design tree.
2.  Rebuild individual parts as necessary.
3.  Solve the mates and locate the parts
4.  Solve the in-context features in parts.
5.  Solve reference geometry and sketches listed after the mates.
6.  Solve assembly features and component patterns.
7.  Loop to step 3 to solve mates that are connected to anything that was solved after the first round on the mates.
8.  Continue to loop until complete.

As you can see, even if you do not have a reference such as "Part A references Part B, which references Part A," it is still possible to get highly convoluted, if not entirely circular loop...

On Matt's site, he has some more rule of thumb regarding in-context assemblies:
http://mysite.verizon.net/mjlombard/incontexttips.html

-Dustin
Professional Engineer
Certified SolidWorks Professional

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources