Large STEP file: Artifacts

Rhino Rhino for Windows
,
1

I received a large STEP file (from a SolidWorks station) to take a look at. I was surprised at the size (498MB). It took about 5 min to open and in the end it had almost no surfaces, just wireframes.

Additionally, there were numerous tubes, planes, angle bar that emendated from the main object.
(jpegs below)

Am on Rhino6 SR35. I have had zero problems with my Rhino package up until this opening attempt.

Any suggestions as to what I should try to get this cleared up?

All comments welcome!

Best regards,
B

STEP pbm1
STEP pbm1571×1014 85.4 KB

2

Hello- Step files are text and will be larger and slower to read in than binary files.
What happens if you change the display mode to Shaded?

-Pascal

3

Greetings Pascal,

Hope this note finds you well!

When I shade some of the parts look proper, but I still have a ton of artifacts … now shaded. Never seen this before.

Appreciate your thoughts!!!
B

image
image496×946 47.2 KB

4

Hi Bruce -

That’s not uncommon when dealing with files that are transferred between systems using the STEP file format. Without having seen your file, I bet that the artifacts that you are seeing are surfaces that have become untrimmed because of tolerance issues with the trimming curves.
Instead of opening, you could try loosening your document tolerances and importing the STEP file. Or have the sender create a file with tighter tolerances.
-wim

5

Wim,

Thank you for the suggestion.

Under Doc Properties (Both Model and Layout) I reduced Absolute Tolerance to 0.01 inch and Angle Tolerance to 2 degrees and tried Importing … with the same results.

Were these the tolerances in my local SW you were suggesting?

Did get this note as an additional clue:
image

The creation of a step ‘with tighter tolerances’ in the originating SW is new ground for me. Do I understand you correctly that in another package (like SolidWorks) … there a similar “Absolute Tolerance” and “Angle Tolerance” like in Rhino ?

Thank you for your good assistance!
Best regards,
B

6

Hi Bruce -

“Reducing” is ambiguous in this context. What was it set to before you changed it?

They might be very well hidden but all SW has to deal with tolerances somehow. It’s been 20 years since I used SolidWorks so I can’t help you with that one.

When you are both on the sending and receiving end of this process, you have a better chance of solving this somehow, but it often boils down to having to untrim surfaces in Rhino and retrimming them.
You could upload the STEP file and have us take a closer look to see what’s going on. If you do, make sure to mention this thread in the comments field on that page.
-wim

7

“Reducing” is ambiguous in this context. What was it set to before you changed it?

Good point.

I went from 0.001 inch to 0.010 inch. So it was a pretty good leap.

Thank you!!!