# Odd surface imported

**URL:** <https://discourse.mcneel.com/t/odd-surface-imported/59464>\
**Category:** Rhino for Windows\
**Created:** [April 1, 2018, 6:54pm UTC](https://discourse.mcneel.com/t/odd-surface-imported/59464 "2018-04-01T18:54:31Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![MSavage](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/msavage/32/154959_2.png) [@MSavage](https://discourse.mcneel.com/u/MSavage)\
**Post date:** [April 1, 2018, 6:54pm UTC](https://discourse.mcneel.com/t/odd-surface-imported/59464/1 "2018-04-01T18:54:31Z")

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I import many STEP files from different places. Sometimes I get strange surfaces imported that I cannot understand.  
The attached for example was part of a bolt head, believe it or not.  
Turning on points shows 4 corners way out in space. Shrinking the surface helps a lot but the display of the surface is still perplexing.  
It’s not an earth shattering thing but if someone could shed some light on the possibilities it might save me some headaches.[odd surface.3dm](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/8/1/81490212830dabc5f161abdb2c51afba89511c6f.3dm) (30.7 KB)

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**Author:** ![pascal](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/pascal/32/479395_2.png) [@pascal](https://discourse.mcneel.com/u/pascal)\
**Post date:** [April 1, 2018, 8:38pm UTC](https://discourse.mcneel.com/t/odd-surface-imported/59464/2 "2018-04-01T20:38:59Z")

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Hello - RbuildEdges will sort that out - the object has (`What` command) seriously out of tolerance edges and vertices:

```auto
  Edge Tolerances: 0.000 to 0.107
    median = 0.000 average = 0.043
  Vertex Tolerances: 0.000 to 0.107
    median = 0.000 average = 0.021

```

especially compared to its size (~.25")

Do you have the step file? Can we have a look at that?

-Pascal

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**Author:** ![MSavage](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/msavage/32/154959_2.png) [@MSavage](https://discourse.mcneel.com/u/MSavage)\
**Post date:** [April 1, 2018, 11:25pm UTC](https://discourse.mcneel.com/t/odd-surface-imported/59464/3 "2018-04-01T23:25:08Z")

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Thanks, Pascal. Tolerances is the culprit !  
Sorry but the STEP files I use is proprietary to the extreme and I can’t share.  
But when I see this again, and I will, I’ll know how to proceed to clean up the mess.

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**Author:** ![MSavage](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/msavage/32/154959_2.png) [@MSavage](https://discourse.mcneel.com/u/MSavage)\
**Post date:** [April 2, 2018, 10:18pm UTC](https://discourse.mcneel.com/t/odd-surface-imported/59464/4 "2018-04-02T22:18:14Z")

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Speaking of STEP files, I thought I was crazy so I experimented inserting a STEP file gotten from GrabCad of a BMW M4 shell.  
It took Rhino 5 1:20 to insert the file and Rhino 6 2:32 for the exact same file (“begin parsing” to “insertion point”)  
So far I like using Rhino 5 better for a lot of reasons. This is just one. Mesh creation is another.  
MS

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**Author:** ![pascal](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/pascal/32/479395_2.png) [@pascal](https://discourse.mcneel.com/u/pascal)\
**Post date:** [April 2, 2018, 10:20pm UTC](https://discourse.mcneel.com/t/odd-surface-imported/59464/5 "2018-04-02T22:20:56Z")

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Hello - can you send us that file or a link to it? In general STEP should be better in V6 - are the results in 5 comparable? For instance, what are the edge and vertex tolerances like in each? (`What` command)

thanks,

-Pascal

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<div class="post-metadata">

**Author:** ![MSavage](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/msavage/32/154959_2.png) [@MSavage](https://discourse.mcneel.com/u/MSavage)\
**Post date:** [April 2, 2018, 11:05pm UTC](https://discourse.mcneel.com/t/odd-surface-imported/59464/6 "2018-04-02T23:05:00Z")

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sure  
[https://grabcad.com/library/bmw-m4-f82-1](https://grabcad.com/library/bmw-m4-f82-1)

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<div class="post-metadata">

**Author:** ![MSavage](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/msavage/32/154959_2.png) [@MSavage](https://discourse.mcneel.com/u/MSavage)\
**Post date:** [April 2, 2018, 11:06pm UTC](https://discourse.mcneel.com/t/odd-surface-imported/59464/7 "2018-04-02T23:06:15Z")

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BTW I think I always use the default configurations for importing in each case.  
Never had the occasion to change anything.