thoughts on top down design 5

[swforge]

Hi all,
Anybody heavy into top down design techniques? I understand the differences between it and bottom up but havent tried it on large assemblies(>1000 parts). Anyone have thoughts regarding performance?

 

[rockguy]

I use top down design all the time. It works well for me but.....my assemblies are typically 100 parts or less. Even in assemblies this size I notice a performance hit. Too bad really. I think its a great way to work but on large assemblies I think it would be too slow.

Rob Rodriguez CSWP

http://www.axiscadsolutions.com

http://www.robrodriguez.com

http://www.robrodriguezblog.com

Eastern Region SWUGN Representative

http://www.swugn.org

http://www.nvtswug.com

SW 2007 SP 2.0

 

[drawoh]

swforge,

I have done top down design on assemblies with over 1000 parts. Top down design is what SolidWorks is all about.

You do not have to make everything parametric at the top level. On a large project, you want to split stuff off so that co-workers can work on them. Inevitably, you are re-using stuff you designed earlier.

When you finalize your manufactured components, you must de-parameterize them. Otherwise, you are going to get random revisions to your solid models. The contents of your fabrication drawings will vary, depending on what you had loaded when you printed them.

JHG

 

[CorBlimeyLimey]

I often use it, but only on very small assys.

The person you should talk with is Mauricio Martinez-Saez. He frequents the official SW forums and is very heavily into large top-down design, combined with extensive use of Excel.

https://forum.solidworks.com/people/1-4Y8EAL

https://forum.solidworks.com/people/1-4Y8EAL?view=overview

https://forum.solidworks.com/thread/27640?start=0&tstart=0

 

[Eltron]

I think people tend to confuse the terms "top down design" with "in context modeling." I use top design as well, but I do not tend to do it within the context of an assembly unless my final product is just going to be a rendering. The in context editing and creation of parts within a SW assembly is just a little too weird at the moment. You have problems with assy performance, and relations are confusing sometimes. With the bolstering of multibody part functionality in recent releases true top down design is much easier within a single part. I believe this is also called "master modeling technique". You create your multibody part (master file) then extract each body to its own part (rt click), then create the assy if necessary. You can even go a step further and use a skeleton part to drive your master model.

I don't know. It just seems simpler for much of what I do. Some things (like pilot plants) probably shouldn't be tackle this way, but for the most part it seems to work well.

Dan

http://www.eltronresearch.com

Dan's Blog

 

[steinmini]

I tried top down modeling (on smaller sub-K assemblies) but only one thing worked as expected. For me it's easier to make a sketch on a piece of paper, define the constraints and start building from scratch. In case it's needed, sometimes it is easier to build a new part "top down", but for me it's not the main advantage of SWX.

 

[swforge]

Thanks to all for your input.
Sounds as though larger assemblies would prove problematic as I suspected. Drawoh seems to have hit the nail on the head in that the creation of subs helps, as it does with bottom up construction. Great concept if the necessary power could be applied. Thanks again

What would you all say to commonly used sub assemblies saved as part files to build upper level assemblies? Could there be performance gains with this method?

 

[rgrayclamps]

Hi, swforge:

It does not make sense to save an assembly as a part.

A sub-assembly is more efficient than a part with same geometries (a multiple bodies part).

Best regards,

Alex

 

[crjones]

I use the top down technique on our assemblies consisting of between 150-200 components. I create a lot reference planes. And I make extensive use of the isolate command to reduce confusion from parts that I am not working with.

 

[Gurjjeet]

Another factor which comes into my mind when I think about top-down design is the clarity of rough draft/design & how
many times you gonna re-use it?

if it is a press tool design for one off part probably not worth the extra time.

But if your company makes steerings for cars. You can make one assy which you can use everytime you get a new design of steering to manfacture.

For me top down is only suitable

If you have around 80% design final in your grey matter.

If you gonna re use it extensivly.

If you are doing a project which will be used repeatedly with minimal changes. Especially if you are sure that the driving concept/component will not change dramatically.

 

[msquared48]

My imagination always works better when riding in a convertible with the top down.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask