# De-unionizing a unionized model

**URL:** <https://discourse.shapr3d.com/t/de-unionizing-a-unionized-model/28447>\
**Category:** Modeling Questions\
**Created:** [October 17, 2023, 7:15am UTC](https://discourse.shapr3d.com/t/de-unionizing-a-unionized-model/28447 "2023-10-17T07:15:00Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![lance1014](https://avatars.discourse-cdn.com/v4/letter/l/3d9bf3/32.png) [@lance1014](https://discourse.shapr3d.com/u/lance1014)\
**Post date:** [October 17, 2023, 7:15am UTC](https://discourse.shapr3d.com/t/de-unionizing-a-unionized-model/28447/1 "2023-10-17T07:15:00Z")

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Is it possible to reverse the union placed on a model so I can edit or delete pieces of the model? Or is the union function permanent? Just curious.

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**Author:** ![Bob3DPO](https://avatars.discourse-cdn.com/v4/letter/b/7993a0/32.png) [@Bob3DPO](https://discourse.shapr3d.com/u/Bob3DPO)\
**Post date:** [October 17, 2023, 10:05am UTC](https://discourse.shapr3d.com/t/de-unionizing-a-unionized-model/28447/2 "2023-10-17T10:05:01Z")

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It will be. It is in the History Based Parametric Modeling (HBPM) version that is currently in beta and open to everyone to try. [https://www.shapr3d.com/2023-summer-product-tour](https://www.shapr3d.com/2023-summer-product-tour)

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**Author:** ![TheBum](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@TheBum](https://discourse.shapr3d.com/u/TheBum)\
**Post date:** [October 17, 2023, 9:26pm UTC](https://discourse.shapr3d.com/t/de-unionizing-a-unionized-model/28447/3 "2023-10-17T21:26:47Z")

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In the current release version, you’re limited to the undo function and the union becomes permanent once you exit the project. As Bob mentioned, the beta allows you to undo any operation at any time, with the potential consequences of affecting other subsequent operations. The one exception to this rule is sketches: you cannot undo a sketch change in history in the present beta.

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**Author:** ![lance1014](https://avatars.discourse-cdn.com/v4/letter/l/3d9bf3/32.png) [@lance1014](https://discourse.shapr3d.com/u/lance1014)\
**Post date:** [October 18, 2023, 5:07am UTC](https://discourse.shapr3d.com/t/de-unionizing-a-unionized-model/28447/4 "2023-10-18T05:07:55Z")

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I see. Undoing the sketch might cause havoc to the structure of the model.

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**Author:** ![TheBum](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@TheBum](https://discourse.shapr3d.com/u/TheBum)\
**Post date:** [October 18, 2023, 5:02pm UTC](https://discourse.shapr3d.com/t/de-unionizing-a-unionized-model/28447/5 "2023-10-18T17:02:07Z")

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Plus, if history recorded every line and curve on a sketch, it would make the history list unwieldy.