To-down design with standard components

[SW]

I tend to use skeleton models and a top-down approach in my
designs. However, I often have to use standard componets in the design so usually
create these as a separate part first and then reference them in my skeleton.
While the technique works, it means I

 

[SW]

I'm still having problems along these lines. The user defined feature approach seems good in principle, but I can't create a UDF using an import feature. Apart from re-modelling any imported iges files, I'm not sure what the best approach is.

Has anyone got any ideas?

Sam

 

[dgs]

You're trying to include geometry from an existing model in your skeleton? Have you tried an inheritance feature? Insert -> Shared data -> Inheritance from other model.

 

[design-engine]

I have a friend (just got off the phone) who works at a major manufacture in the Chicago suburbs and he is pissed. I guess they hired a design firm in Boston who gave them a master merge model as a part of their deliverable. My friend is so mad now after he asked me "what reason would anyone use master merge" and listed to my response... I said that's how solidowrks does it....

1 No... my answer was if they don't have AAX then that's the only way to do it. or copy a surface out of a part thru an assembly...

2 You could also use an external copy geometry without using a skeleton file at all. This technique is cool because there is no assembly link.

3 Inheritance is cool for stuff like Pro/CABLE because you can get the assembly as a single feature (surface) in a part. I prefer the item 2 from above because imagine the entire f35 jet in a single proe session to route? With item 2 ECG technique one can get single surfaces like bulkhead geometry in place and keep things small

4 then there is 'publish geometry' (an extension of ECG and works in conjunction with skeletons introduced in 1998) which works nicely when there are large teams at play and everyone is using intralink or PDM tools. I like to publish a surface quilt and make the feature a footer so it sits on the bottom of the model tree like a sheetmetal flatpattern.

5 The copy a surface from a part thru an assembly trick ... don;t let your cad manager find out because that trick drags a whole lot of mess to PDM intralink team center.That's how we did it back in 1995 and what caused the sysops to complain ... item 1 .... considered bad practice now-a-days.But I hear from past students that everyone does 1 and 5 at ... I will not name companies.

All require AAX except item uno y cinco




Edited by: design-engine

 

[SW]

Thanks chaps,

Inheritance does the job nicely. I've just used a coordinate system to place the feature and it is easy to handle.

Sam

 

[dgs]

I have a friend (just got off the phone) who works at a major manufacture in the Chicago suburbs and he is pissed. I guess they hired a design firm in Boston who gave them a master merge model as a part of their deliverable. My friend is so mad now after he asked me "what reason would anyone use master merge" and listed to my response...

Sounds like he needs a new design firm.

We always review things like TDD before hand to know what the client is comfortable with. We just finished a project for a major manufacturer in the Atlanta area and gave them an "outer surfaces" design model that was actually a skeleton driven assy. with all the copy & publish geometies set up. They were thrilled.


Maybe he should call us next time.

 

[SW]

I'm doing the same sort of thing, this time the I'm referencing an assembly rather than a part so inheritance features doesn't like it, nor do external copy geom features. Instead, I've used an external shrinkwrap. It seems to work alright, but means I've got to manually update the shrinkwrap feature if I move the placement coordinate system.

Is this a good or bad technique?

Sam

 

[design-engine]

Doug,

I helped him write up a RFP that defines the deliverable more specifically. do you have an example you can email me/him?Ill put you in touch ... maybe you can sell a big one to them? Ill put in a good word.They make Garage Door openers... Tad there teaches our mechanism classes. Very smart fellow and races bikes too... check you pm
Edited by: design-engine

 

[SW]

I've just used a merge rather than inheritance feature to propagate the geometry and it gives me problems updating when I make changes. Changing it to an inheritance feature sorts it out but I've noticed there will be the same problem if I move the coordinate system that positions my external shrinkwrap feature.

What is the best way to reference an assembly? I can't just reference each individual part since the position of the parts needs to be reflected.

Sam

 

[Zaki]

If you have (or you can get it) Pro/Intralink, its too easy to work in assembly. You can use both strategies, top down or bottom up. Your links never fail and you don't face those messy things. Other wise, you must be careful to handle assemblies and folders. A little mistake can cause you week, full of tension.

 

[design-engine]

sorry SW:
Merge is the problem. That is what the design firm did - master merge - but that's considered the old top down design (1995-1997) technique. (not as old as surface copy in assembly mode). This merge technique is all solidworks lets you do BTW.

The more accepted methodology is ECG or Copy Geometry 'insert part' technique that requires the added module AAX for top down design.

 

[SW]

No problem, I bit of digression can be a good thing. I often use copygeom features but this only allows me to reference one part at a time. Ideally I would use a pubgeom feature first but I can still only reference one part.

Any other ideas?

Sam

 

[design-engine]

The publish geometry was designed by PTC for teams. (someone chime in if they have other purpose for pub geom) A person on the first floor working within a team can publish a surface geometry for the example we'll call a b-side geometry. That way another designer on a different floor can grab that same skeletal file and see right away the published geometry he needs to create the shell on his part. Because the published geometry is often stuffed into a footer in the feature tree the surface file is easy to pick.

In the same respect and in the same skeleton model the 1st designer on the first floor can/might also publish a c-surface or a mid surface for a guy on the fourth floor who is doing the ribs. He will cut away the ribs with the mid surface and merge from the skeletal model.

Back in the early days of top down design... before 1994 we wanted to get a group of people all working on the same housing. Team up on it so to speak. < that is a different story...

Imagine a mouse for example. Someone skilled at surfacing will tackle the skeleton-surface geometry for the mouse then break apart each plastic component for other team members to manage b-side geometry. Such parts as bosses, mounting holes for MB, and scroll wheel locations.... That way we get to throw more people at one project.
Edited by: design-engine

 

[SW]

I regularly use pubgeom features in the way you describe but in this instance, I can't reference more than one part in this standard assembly unit that I'm fitting into my design. Is there a better way than using an external shrinkwrap to reference geometry in one part to assembly geometry?

Also, I was under the impression that external inheritance is the preferred technique over external merge to bring all the geometry from one part into another, but merge seems more robust as it does not seem to require the reference part to be in session when changing the merge placement. Also, the box to stop the inheritance bringing in the datum planes is greyed out, and they all re-scale to fit the entire part. I could well be missing something so some clarification would be appreciated.

Using copygeom features with or without pubgeom features requires the original part to be in session to update the placement, but it seems better than an inhertiance feature.

Sam


Edited by: SW