# Unable to Subtract

**URL:** <https://discourse.shapr3d.com/t/unable-to-subtract/3968>\
**Category:** Modeling Questions\
**Created:** [February 3, 2019, 6:19am UTC](https://discourse.shapr3d.com/t/unable-to-subtract/3968 "2019-02-03T06:19:48Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![American1776](https://avatars.discourse-cdn.com/v4/letter/a/85e7bf/32.png) [@American1776](https://discourse.shapr3d.com/u/American1776)\
**Post date:** [February 3, 2019, 6:19am UTC](https://discourse.shapr3d.com/t/unable-to-subtract/3968/1 "2019-02-03T06:19:48Z")

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I am loving Shapr3D so far, but this one issue is driving me crazy. I have a rather complex and large object that I need to subtract from. I have tried pushing the face down with a sketch, but it says “body generation failed after extrusion”. When I try to create a shape and then use the subtract tool, I get an error saying “the boolean failed”.

Here’s a link to a video of the issue: [http://sendvid.com/zdxxhzd6](http://sendvid.com/zdxxhzd6)

Any idea on how I can get around this?

Thanks.

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**Author:** ![hamedtopic](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/hamedtopic/32/3371_2.png) [@hamedtopic](https://discourse.shapr3d.com/u/hamedtopic)\
**Post date:** [February 3, 2019, 8:14am UTC](https://discourse.shapr3d.com/t/unable-to-subtract/3968/2 "2019-02-03T08:14:32Z")

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Unfortunately we’ve the same similar bothersome issues and nobody, team members, answered yet!

> [@Import of Polymesh solids from Rhino in Parasolid or STEP files](https://discourse.shapr3d.com/t/import-of-polymesh-solids-from-rhino-in-parasolid-or-step-files/3963/3):
>
> I reported the same problem to the guys: here is the link:

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**Author:** ![DanielR](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/danielr/32/582_2.png) [@DanielR](https://discourse.shapr3d.com/u/DanielR)\
**Post date:** [February 3, 2019, 1:00pm UTC](https://discourse.shapr3d.com/t/unable-to-subtract/3968/3 "2019-02-03T13:00:07Z")

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Hi Hamed - thanks for keeping on our toes 🙂 but it will be a different problem probably.

@American1776 The most likely problem here is that you would create a non-manifold body by the subtract operation. You can read more about it here [https://www.sculpteo.com/blog/2017/10/18/how-to-fix-non-manifold-geometry/](https://www.sculpteo.com/blog/2017/10/18/how-to-fix-non-manifold-geometry/). I circled the problematic area for you:

![59](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/2X/7/7aab46236344d102da741e32207012a517cc91eb.jpeg)

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<div class="post-metadata">

**Author:** ![hamedtopic](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/hamedtopic/32/3371_2.png) [@hamedtopic](https://discourse.shapr3d.com/u/hamedtopic)\
**Post date:** [February 3, 2019, 1:09pm UTC](https://discourse.shapr3d.com/t/unable-to-subtract/3968/4 "2019-02-03T13:09:25Z")

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Hi Daniel, wish you and the rest of the family best of luck. Btw, could you find the problematic issue for my case ?!

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**Author:** ![DanielR](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/danielr/32/582_2.png) [@DanielR](https://discourse.shapr3d.com/u/DanielR)\
**Post date:** [February 3, 2019, 1:20pm UTC](https://discourse.shapr3d.com/t/unable-to-subtract/3968/5 "2019-02-03T13:20:39Z")

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Not yet, but I’ve reported it - I’ll look into what is its status tomorrow

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<div class="post-metadata">

**Author:** ![American1776](https://avatars.discourse-cdn.com/v4/letter/a/85e7bf/32.png) [@American1776](https://discourse.shapr3d.com/u/American1776)\
**Post date:** [February 4, 2019, 8:09am UTC](https://discourse.shapr3d.com/t/unable-to-subtract/3968/6 "2019-02-04T08:09:09Z")

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Thank you very much Daniel. That was in fact the issue.

I presume it was considered a non manifold because those two lines intersected together at the edge. That’s surprising to me because those lines are semi-randomly overlayed on top of the surface. It was just a coincidence that the intersection happened to be so close to the edge that they were considered touching.

Thank you for the help.

![image](https://cdck-file-uploads-us1.s3.dualstack.us-west-2.amazonaws.com/flex002/uploads/shapr3d/original/2X/4/4e4913029035b734a4102bbbe105ad30df83603e.png)