# Subtraction and union problems

**URL:** <https://discourse.shapr3d.com/t/subtraction-and-union-problems/14529>\
**Category:** Modeling Questions\
**Created:** [August 22, 2021, 9:50am UTC](https://discourse.shapr3d.com/t/subtraction-and-union-problems/14529 "2021-08-22T09:50:39Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![Eightbitghost](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/eightbitghost/32/11683_2.png) [@Eightbitghost](https://discourse.shapr3d.com/u/Eightbitghost)\
**Post date:** [August 22, 2021, 9:50am UTC](https://discourse.shapr3d.com/t/subtraction-and-union-problems/14529/1 "2021-08-22T09:50:39Z")

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I’m having a small problem trying to create a screw thread in a design. I had been using a imported thread and then either using the union function or the subtract function depending on the application. For some reason on my current project I’m having problems using either of these functions. Addition comes up with a Boolean error and subtract is allowing me to select the items but not complete the action.

Any help would be greatly received.

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/2X/b/b8fc6bc10bb6c9de630763ccdf0ec3748ad8ff70.jpeg)

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**Author:** ![Rohan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/rohan/32/15410_2.png) [@Rohan](https://discourse.shapr3d.com/u/Rohan)\
**Post date:** [August 22, 2021, 11:38am UTC](https://discourse.shapr3d.com/t/subtraction-and-union-problems/14529/2 "2021-08-22T11:38:44Z")

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In which format did you imported the thread?

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**Author:** ![Eightbitghost](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/eightbitghost/32/11683_2.png) [@Eightbitghost](https://discourse.shapr3d.com/u/Eightbitghost)\
**Post date:** [August 22, 2021, 12:30pm UTC](https://discourse.shapr3d.com/t/subtraction-and-union-problems/14529/3 "2021-08-22T12:30:18Z")

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I think it is in a .STL format

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**Author:** ![Rohan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/rohan/32/15410_2.png) [@Rohan](https://discourse.shapr3d.com/u/Rohan)\
**Post date:** [August 22, 2021, 2:24pm UTC](https://discourse.shapr3d.com/t/subtraction-and-union-problems/14529/5 "2021-08-22T14:24:00Z")

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I am not able to figure out the problem. Can you please send your workspace??

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**Author:** ![Eightbitghost](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/eightbitghost/32/11683_2.png) [@Eightbitghost](https://discourse.shapr3d.com/u/Eightbitghost)\
**Post date:** [August 22, 2021, 3:44pm UTC](https://discourse.shapr3d.com/t/subtraction-and-union-problems/14529/6 "2021-08-22T15:44:01Z")

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Sorry, How do I do that?

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**Author:** ![Eightbitghost](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/eightbitghost/32/11683_2.png) [@Eightbitghost](https://discourse.shapr3d.com/u/Eightbitghost)\
**Post date:** [August 22, 2021, 5:00pm UTC](https://discourse.shapr3d.com/t/subtraction-and-union-problems/14529/7 "2021-08-22T17:00:28Z")

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[problem.zip](https://discourse.shapr3d.com/uploads/short-url/okJR6Rjawu0lbkKA4xPkXuc5Osg.zip) (1.4 MB)

Think I figured out how to do it, this is the file

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<div class="post-metadata">

**Author:** ![Eightbitghost](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/eightbitghost/32/11683_2.png) [@Eightbitghost](https://discourse.shapr3d.com/u/Eightbitghost)\
**Post date:** [August 22, 2021, 5:29pm UTC](https://discourse.shapr3d.com/t/subtraction-and-union-problems/14529/8 "2021-08-22T17:29:21Z")

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I think I’ve sorted it, it all works now that I’ve found a different file to use for the thread I tried it with a .igs file and everything works as it should 👍