Hi all,
I was wondering is there any way I can extend the surfaces highlight in blue? I have try to use "surface extend" feature but it said "Could not extend surface due to geometry condition". If I can't use "surface extend" feature, what other feature I can use to achieve the same result? 
Joseph, without seeing/playing-with the model, the only other long-shot I could recommend is the Untrim feature. Do you really need to extend all the edges of all the surfaces? If so, by how much?
Maybe try one edge at a time to determine which edge won't allow extension? Trouble-shoot from that point.
Hi all,
Thanks for the reply. I just upload the model.
Have been try extend them individually, but the end result is not what I want. Hope any of you can solve my problem. Thanks!
A big problem with this model, and what you wish to do with it, is the fact that so many of the outer blue surfaces are just barely intersecting the red "bottom" surfaces. Solidworks can't figure out to do with the surfaces that would become non-existant, and the surfaces that don't intersect cleanly after the extension, so it just plain won't do it.
One way to maybe get this to work would be to simplify that outer blue surface such that it becomes a single "face" instead of a patchwork of faces, and a good way to do this is in the profile sketches that set up the loft.
I see that the first feature is "imported" so I don't know if you have access to the model where the loft occurs. If you do, try using a "fit spline" on all the profile sketch entities that make up the blue outer surfaces. If you can get that to work, the outer blue surfaces should select as a single face. Then you might have a chance at extending the edges of that single surface.
It still might not work though, and the problem may be that there is simply no way to extend the edges given the geometry that you're starting with. The answer may be that you need to adjust the original geometry to allow the extention you're trying to achieve.
I attached a PDF showing where the trouble most likely is coming from.
The problem is that there is surface data missing. I don't believe you will get a clean extend out of this. It is not possible to know exactly how the surface was intended to flow in the missing areas. Some if it can be extrapolated but most of it cannot. So the real issue comes down to what exactly are you going to do with the surface one you have it extended? If this is for mold tooling or something similar, then so long as the surfaces displayed remain intact, you should be able to manipluate the rest in an approximation and still be fine. If only the presented surfaces are required to be accurate, then you can go through a lengthy process of fixing the surface, otherwise you will need more data from your source to get what you need.
First there are two spots in the offset surface that you missed when creating it that have made gaps in the surface. I'd first try using the Untrim feature to straighten as many of the edges as possible and then 3D sketch splines in to use with the Fill feature to approximate the surfaces.
What do you expect, how these highlighted faces should be extended?
Would you be able to upload the part as well? Pictures may say a thousand words, but models sometimes speak volumes.
Chris