imported geometry

coied/offset geometry is in another file, and they are linked in context of an assembly.

Why not just work directly off the imported model?

I am finishing a project where exterior surfaces were determined by an outside industrial designer using Ashlar-Vellum. I found that most of the Vellum-generated surfaces could be reproduced as sweeps, usually an arc or ellipse swept along a spline. I would offset and untrim a face from the imported geometry and then use that surface to determine curves for sweeps.

I tried working from the imported geometry but usually there is no draft on the parts and I have to add that. Also, I like to re-create the geometry so that I have the flexability to modify easily if required.

I don't know what is worse, working from the original geometry or offsetting some surfaces and then having to rely on another part/assy for the in-context stuff.

Try ShapeWorks at

ShapeWorks can extract all the surfaces to new or existing file. The new surface model will not depent on the original.

Michael

I've had the time and ability to recreate everything from scratch. For me, the imported file serves as a template to match up lines and compare surfaces.

Remember that most faces you see on an imported model are trimmed patches of surfaces with larger definitions. When these surfaces are untrimmed, it's often not too difficult to divine the surface construction and replicate the surface in SolidWorks.

It is important that this be done with untrimmmed surfaces (which are then trimmed/knit as needed). Attempting to replicate a surface based on trimmed edge geometry usually results in surfaces that are overdefined, which results in odd wrinkles.

Here's been my experience. I've taken an original imported part and used is once and added all my features. I didn't like that because I want to be able to change all entities if required. I've successfully re-created parts using (as you stated) the orig import as a template. I've also created parts the same way but had to use offset of an imported surface because I could not duplicate. The reason I am asking how everyone does it now is because on this new project I have having even more of a difficult time duplicating surfaces and I am finding myself using the offset (in context) a lot more on this project. I am just trying to avoid problems in the future with these parts. I guess I need to work on creating original surfaces in SW and matching it up with the import?

It's a tough call. All design is about context. You can make your best educated guess, but sometimes design intent shfts in such a way as to blow your foundation apart.

In my field, it is common to be dependent on imported geometry to define a design. The risk is that the very foundation of the model may change.

There are tools to cope with this. Imported feature can be redeifined without creating a new file. Models can be structured to minimize the damage done by replacing "foundation features". It is important to learn how to repair features by adjusting/replacing their references.

I hear what you are saying. I've run into problems in the past where the import changed and my design was in context with it. SW tech services say not to build in context. Makes sense but does not at the same time. I usually build in context and then break the associativity and put my own dims in. My particular problem right now is I can't define some surfaces without using imported surfaces. If I try to break the context of the surface I get errors. Not sure how to handle that.

That's our theory. If we can't match the original ID in SW, then we change the design enough to make it work in SW. Next project we are hoping to set up tighter design rules (primarily minimum radii) with the ID firm before we get started with the surfaces. Since our favorite ID firm also has SW, we will probably ask them to give us shellable SW models.

Jerry Steiger Tripod Data Systems "take the garbage out, dear"