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How do I add thickness?
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January 16, 2019, 04:22:23 AM
The attached image is an exploded view that shows the pieces that I want to assemble.  The result has to be a Solid model in STEP format for use by a CNC machine.

The green portions were originally one high-res STL scan of sunglass frames I have been working on, off and on, for months.

I want to thicken the frame by 1 mm and create a triangular groove for the lens insertion.  The following techniques have been tried and failed badly:

1) Created two Arcs, above and below the frame and Lofted them to create an ACIS Surface which was Exploded to a TC Surface that was used to Slice the frame.  The rear portion was moved back 1 mm.  I then arduously traced (because Extract Entity doesn't work on Surface objects) the outer frame boundary and the lens boundaries, then copied them back 1 mm so that they could be Lofted together.  The three pieces were then 3D Added and I converted the result to an ACIS Solid.  The problem showed up when I 3D Subtracted the groove for mounting the lenses.  The supposedly solid object was hollow.

2) The STL file was Simplified to 20%, then converted to an ACIS Solid.  An ACIS Surface was created from the two Arcs and used to Slice the frame. 
 a) Face2Face Lofting failed. 
 b) Extrude To Face failed.
 c) Extract Entity / Extract face from body (F) on the rear facet of the front frame part worked (sort of... its outer surface seems to be orthogonal to the facet, so it didn't align smoothly with the rear frame), but it failed to 3D Add to either the front or rear frame parts.
 d) The frame and lens outline traces were copied, moved behind the rear frame and converted to zero thickness (Scale Y by 0.001 repeatedly, because just setting Size Y to 0 failed).  I Extruded the frame outline forward, and sliced in a couple different ways:
 d1) Moved original Surface Slice forward 0.001 mm and copied it 1.002 mm to the rear and used both to 3D Slice the Extruded outline, then deleted all but the middle piece (coral color in the image).  This failed to 3D Add.
 d2) Used the original Surface Slices (with a 1.000 mm separation) as in d1.  It also failed to 3D Add.
 d3) Tried to scale the filler in Y by 1.01.  This failed, too.

I had previously copied the frame back 1 mm and 3D Added the two pieces together.  This worked, but the file size nearly quadrupled.  I'd prefer to have a cleaner result.

I've run out of ideas.  Can anyone suggest a technique to accomplish this? 

Thanks in advance,


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