# Troubles with „subtract“-command

**URL:** <https://discourse.shapr3d.com/t/troubles-with-subtract-command/10575>\
**Category:** Modeling Questions\
**Created:** [December 29, 2020, 11:07am UTC](https://discourse.shapr3d.com/t/troubles-with-subtract-command/10575 "2020-12-29T11:07:32Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![ShaprFlo](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@ShaprFlo](https://discourse.shapr3d.com/u/ShaprFlo)\
**Post date:** [December 29, 2020, 11:07am UTC](https://discourse.shapr3d.com/t/troubles-with-subtract-command/10575/1 "2020-12-29T11:07:32Z")

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Hi there, I am using Shapr 3.54.0 on iPadOS 14.2 and just recently experiencing troubles with the „subtract“-command: After selecting two or more objects, (+) and one or more (-), the „ready“ command-button does not appear to progress the command (…sorry, I am using the german version, so I am a little guessing about the command-names in English)  
Other commands like „cut“ or „combine“ work flawless: After selecting at least two objects, the „ready“ command-button appears and allows progressing the command…  
…any clue?  
Best regards, Flo

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**Author:** ![KPeter](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/kpeter/32/7644_2.png) [@KPeter](https://discourse.shapr3d.com/u/KPeter)\
**Post date:** [December 29, 2020, 11:44am UTC](https://discourse.shapr3d.com/t/troubles-with-subtract-command/10575/2 "2020-12-29T11:44:54Z")

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Hi @ShaprFlo, I would like to ask you to update to the latest version (3.56.1), then can you please upload some screenshots of the issue or the .shapr workspace?

Subtract usually fails when it has been applied once and the tool and target bodies were not deleted. In those situations, there is no body to subtract. Can you please check in the Items List if there is a body which is already subtracted?

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**Author:** ![ShaprFlo](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@ShaprFlo](https://discourse.shapr3d.com/u/ShaprFlo)\
**Post date:** [December 29, 2020, 5:35pm UTC](https://discourse.shapr3d.com/t/troubles-with-subtract-command/10575/3 "2020-12-29T17:35:04Z")

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Hello Peter, many thanks for your fast reply. Unfortunately the update did not make the breakthrough. After playing arround now for some time it appears to me as if it is a kind of „rendering“-issue. Both, (+) and (-) bodies are very narrow on one surface

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/2X/7/7329f187d0a435cc5769c5dcbe55fd0d99a428b2.jpeg)

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**Author:** ![ShaprFlo](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@ShaprFlo](https://discourse.shapr3d.com/u/ShaprFlo)\
**Post date:** [December 29, 2020, 5:36pm UTC](https://discourse.shapr3d.com/t/troubles-with-subtract-command/10575/4 "2020-12-29T17:36:12Z")

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The „ready“ command does not appear

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/2X/b/b416143196ac280af3720c3c4a151e0c3ac2b121.jpeg)

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<div class="post-metadata">

**Author:** ![ShaprFlo](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@ShaprFlo](https://discourse.shapr3d.com/u/ShaprFlo)\
**Post date:** [December 29, 2020, 5:37pm UTC](https://discourse.shapr3d.com/t/troubles-with-subtract-command/10575/5 "2020-12-29T17:37:11Z")

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When changing the dimension of the (-)-body just a little (…from 30 to 30,01), the concerned surfaces do not „overlap“

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/2X/7/7de975deb7a0303efe55bb495f3635b8b800df8b.jpeg)

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<div class="post-metadata">

**Author:** ![ShaprFlo](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@ShaprFlo](https://discourse.shapr3d.com/u/ShaprFlo)\
**Post date:** [December 29, 2020, 5:38pm UTC](https://discourse.shapr3d.com/t/troubles-with-subtract-command/10575/6 "2020-12-29T17:38:01Z")

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…and the „ready“ command is available

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/2X/6/6becba7ad5c44989be83825a3b68614684a44440.jpeg)

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<div class="post-metadata">

**Author:** ![KPeter](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/kpeter/32/7644_2.png) [@KPeter](https://discourse.shapr3d.com/u/KPeter)\
**Post date:** [December 29, 2020, 8:36pm UTC](https://discourse.shapr3d.com/t/troubles-with-subtract-command/10575/7 "2020-12-29T20:36:55Z")

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Yeah, it looks like the two surfaces on the perimeter are covering each other. Or they are treated like covering each other, which means that the distance between them is smaller than the tolerance Shapr3D works with. If subtraction would be allowed in this case, the result could be a surface, which is currently not supported.  
This would not be a problem for Union and Intersect, but as you have found out the Subtract tool works well if there is a clear intersection between the tool and the target body.