Chapter 30: Using Imported Geometry and Direct Editing Techniques
Best Practice
When ever you export data to another CAD system, it is considered best practice (and professional courtesy)
to “round trip” (save out, then read back in) the data to make sure that you can accurately read the data that
you wrote out. You should not send someone else data that you cannot read back into the CAD system that
created it. This may be of little comfort to you when you are the one receiving the bad data, but if you receive
bad data, you have every right to go back to the creator and ask if he can round trip his data. It might be that
he can adjust tolerance or accuracy settings to give you better data, or possibly that his model had some prob-
lems that he didn’t know about when he exported it out to you. n
If you get bad data and you do not have access to the source, and automatic and manual errors
prevent you from using the data, then the next best thing is to rebuild the part using the error
filled data as a reference. This is never a pretty thing, but if you really need the data to be clean,
and there is no other way, this is what you need to do.You can take measurements in one file and build a new part in another file, build one file in the
context of an assembly directly over the problem file, or even rebuild it as a multi-body part.Tricking data into working
Occasionally you can employ tricks to heal problem imports. Simply saving out of SolidWorks as
Parasolid and reading back in repeatedly can sometimes heal troublesome imported geometry. I
frequently use Rhino to import problem files, then export from Rhino as a Parasolid. Rhino is an
inexpensive surfacing application. You can read more about it at http://www.rhino3d.com. You can
download and install a trial version that allows you to save 25 times. Rhino works great as a trans-
lator because it reads and writes many file types that SolidWorks does not read. Sometimes when I
get a very bad IGES file, I read it into Rhino, and save it out as Parasolid, then read the Parasolid
into SolidWorks. Sometimes this will repair the data to the point that SolidWorks can deal with it
more effectively.This is not to say that Rhino is a better file translator than SolidWorks, because this workaround
does not always improve things. It is sometimes effective, and because it is free, the only thing it
will cost you to try it is time.You can use the same trick with other CAD packages. For example, if you know that you have an
IGES file from VX, and you are having difficulty reading it into SolidWorks, it might pay to down-
load a trial version of VX (www.vx.com) and see if it can import the data and re-export. It is best
to use the source program to read and re-export when possible.Ensuring that you get good data
If you can’t get a SolidWorks file from someone who needs to send you data, the type of transla-
tion file that you get has a huge influence on the likelihood that your translation will be successful.
Ask for data in this order:- Parasolid (including native formats that use Parasolid, such as NX, Unigraphics,
and Solid Edge). Parasolid can come in text format (.x_t) or binary format (.x_b).
You may also see file extensions such as .xmttxt from older versions of Unigraphics. Of