Newbie help, please: Importing .igs assembly and parsing back into sub components

I drew up a small electromechanical actuator in SketchUp. (motor, motor housing, thrust tube, acme screw, acme nut, bearings, etc etc)

I worked with a friend to create it in SolidWorks so i’d have “real CAD”. I want to see if Rhino can meet my CAD needs, so I downloaded the trial. My friend sent me the drawing in .igs format. I’m able to open it in Rhino and it looks great. When I click on it, it seems to be just a jumble of disassociated surfaces.

If this were SketchUp, I’d be hiding surfaces until I could clearly click on or select all the surfaces that make up an individual part that makes up the actuator. I’d then “connect all surfaces” and “Group”. Voila - That is one component/part for the actuator. Name it, put it on a layer or something, hide it, unhide the other stuff, and start putting together the next part.

Eventually I’d have complete sub components that I could put together to make the actuator. I’d also produce mfg drawings from here.

Is there a video tutorial that would provide some guidance on these processes? Thanks in advance for the help.

First of all, just plain avoid the .IGES format. Nothing is joined as you saw. I’m not sure why people still use this.

Secondly, get another export using the .STEP format and everything that was joined will stay joined. Even better, the STEP format is 100% NURBS and will act and edit just like native Rhino geometry. You will love it!

OK. I will see if I can get it in .stp format. Thanks for the tip.

You’re not going to get STEP from SketchUp. It’s just a mesh modeler intended for visualization. In that sense it is not a CAD application that makes models you can manufacture.

On tech support, you mentioned someone had remodeled everything in SolidWorks.
Rhino can Open/Import SolidWorks Part and Assembly files. These will import as joined polysurfaces. Watch out that SolidWorks and Rhino use different coordinate systems.
Rhino uses Z-up and SW uses Y-up.

Understood that I can’t go get a step file form SU. I am going to ask my friend to send me a .stp file instead of the igs file. That will be “attempt 1”. Are you saying I am better off asking for/opening the part and assembly files?

From SolidWorks you can export STEP or their native Part files. Try both and see what works better for you.

.sldprt format, right?

Yes, SolidWorks SLDPRT and SLDASM files

Success! I was wrong - they were using ProE.

They sent the .stp, I opened it (got a warning about faces which I’d like to better understand).

I changed to shaded view. I clicked on the ass’y and it was all one part. I used the explode command. It looks like it exploded it “one level” and I have the individual parts/components that make up the actuator.

I’ll work with this a bit and see what happens. Thanks again.

I have a couple other questions about will post those elsewhere to keep this a clean thread for future searches.

@chuck might chime in here to explain all the details (since the help file doesn’t really explain all that much, @margaret) but I would venture to say that Rhino needs to check if edges are shared between faces of a polysurface to the tolerance that either is in the STEP file itself (when opening) or in your Rhino template (when importing). This might lead to long loading times and as such you could opt to not join faces of a single polysurface (giving you the same as an IGES would), or set a limit to how many faces should be joined. I’ve imported STEP files into Rhino for a long time and never had to change the defaults. So my advice is to stick to these defaults.

An assembly in STEP format is added to the Rhino document as a block with nested blocks (children). I’ve never understood why that is this way as a block is a way to reduce file size and computation loads when you have identical objects in different locations (translations and rotations). When importing a STEP into Rhino, everything is turned into a block (unless you import a single object). To explode all levels at the same time, use the ExplodeBlock command.

Use the ExplodeBlock only (or Select --> Block --> Explode) The standard Explode command will work, but you’ll probably end up exploding the geometry (like I usually do) and then you got big fat mess on your hands.