External references 1

[dgiy]

Just wanted the expert's opinions on external references.

Is there any of you who swear by them or swear at them.
Would some of you be lost without them or some wish they had been left out of SW??

I have never made much use of them but was wondering if maybe I could increase my productivity by using them.

What pitfalls should I avoid etc.

Any comments would be appreciated.

Thanks,
DGIY

BTW SW 2004-SP1

 

[TheTick]

Like any tool, it depends on the hands and mind of the user. They are definitely a great aid to design.

Still, I have a "split-personality" about the use of external references. In design phase, I use them and keep them. When a part is released for production, I make sure that each part file is a stand-alone. I make liberal use of layout sketches, so reattaching external references when needed for changes presents little difficulty.

"When everyone is thinking alike, no one is thinking very much." --Eckhard Schwarz (1930--2004)

http://www.EsoxRepublic.com

 

[MadMango]

I love external references when in the design phase of a project. But once the design solidifies, I remove them.

[blue]"But what... is it good for?"[/blue]
Engineer at the Advanced Computing Systems Division of IBM, 1968, commenting on the microchip.
Have you read faq731-376 to make the best use of Eng-Tips Forums?

 

[CMcF]

I agree fully with TheTick and MadMango. The main pitt fall is losing track of what refrences what, and in what direction. So I use a "control part" which contains all my datum planes, axes, sketches, but no solids. I insert this into all my sub assemblies for a machine. I then make all external refrences via the "control part".
For example, a single sketch in the control part will drive the hole postions in two different mating assemblies. You can open each assembly on its' own with out the hole positions being "out of context".

 

[SBaugh]

If your looking for direct Automation then External refernces is the way to go. I used them for automation in my last job. One job I did for the company cut design time by 75%, from thought to finished drawings. I used External references, and Design tables that had many configurations.

You can have master files and simply have them copied to a directory for all jobs. This away the masters are never affected by any change.

See web site. I have posted information regarding this:

http://www.scottjbaugh.com/Design_Portfolio/SW Models DT.htm

Scott Baugh, CSWP

http://www.3dvisiontech.com

http://www.scottjbaugh.com

faq731-376

 

[timbochung]

Hi All,

Prior to releasing drawings - is it preferable to break or lock references? If breaking - do you redimension the unconstrained sketches?

The control part technique by CMcF is pretty cool - I'm going to try it out on my next design - any other words of wisdom when mating external references to a common layout sketch?

Tim

 

[MadMango]

Our products move from R&D--> Limited Production--> Full Production. We break all relations and redimension only after projects make it to Full Production.

[green]"But what... is it good for?"[/green]
Engineer at the Advanced Computing Systems Division of IBM, 1968, commenting on the microchip.
Have you read faq731-376 to make the best use of Eng-Tips Forums?

 

[engAlright]

What an excellent topic for a friday afternoon...

We also try to make sure all parts are standalone before moving them to production. We've been burned once too often by parts that were related to parts that either didn't exist or had been changed so drastically that they couldn't be used as a modelling context. In-context is still used quite frequently for development.

I also like to keep all external references to within an assembly - multiple contexts are dangerous! It's best if that assembly is small - I have seen small parts (gussets, bosses) designed in context of whole machine models! Wouldn't want to the guy who has to change the shape of that gusset!

I am also a fan of designing using a "base part" or layout sketch to which all other parts are related. This prevents circular references and keeps everything a little neater.

 

[timbochung]

What are your thoughts about imported iges models as the point of reference?

Would anyone add layout sketches to this part or is it better to have another "base part" within the assembly that has all the layout sketches and planes?

 

[CorBlimeyLimey]

The problem with a "base part" is that it will show in a BOM, but it is useful to keep all the planes & sketches together.
An alternative is to create all the planes & layout sketches inside of a folder. That way the feature tree is kept smaller & tidier & will not affect any BOMs.

 

[TheTick]

If you make the base part an envelope, it doesn't show in the BOM.

I do this with hinge models. The moving leaf is designed in the closed position as an envelope. The moveable component is the same model as the base part, but a regular component.

"An object at rest can not be stopped."

http://www.EsoxRepublic.com

 

[ctopher]

My biggest problem with references is even if you break them, when you part/assy is checked into PDMW, it wants to check in the external ref also ... which usually don't want.

 

[TheTick]

I do more than break external references. I remove them and replace them with local constraints.