# How to reference existing dimensions and define parameters

**URL:** <https://discourse.shapr3d.com/t/how-to-reference-existing-dimensions-and-define-parameters/35647>\
**Category:** Modeling Questions\
**Created:** [December 18, 2024, 8:03pm UTC](https://discourse.shapr3d.com/t/how-to-reference-existing-dimensions-and-define-parameters/35647 "2024-12-18T20:03:56Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![CerialPhreak](https://avatars.discourse-cdn.com/v4/letter/c/ce7236/32.png) [@CerialPhreak](https://discourse.shapr3d.com/u/CerialPhreak)\
**Post date:** [December 18, 2024, 8:03pm UTC](https://discourse.shapr3d.com/t/how-to-reference-existing-dimensions-and-define-parameters/35647/1 "2024-12-18T20:03:56Z")

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I’m a recent convert from Fusion and I’m trying to figure out how to reference dimensions and/ or define parameters.

Two example scenarios:

1. Create a circle with diameter 4mm (let’s call this D1). Create a second circle with a diameter of D1 / 2 (half of D1).
2. Define a parameter of 4, named “diameter 1”. Create a circle who’s diameter is driven off “diameter 1”.

Any general tips with working with parameters would be greatly appreciated!

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**Author:** ![SCALEMODEL](https://avatars.discourse-cdn.com/v4/letter/s/77aa72/32.png) [@SCALEMODEL](https://discourse.shapr3d.com/u/SCALEMODEL)\
**Post date:** [December 18, 2024, 9:40pm UTC](https://discourse.shapr3d.com/t/how-to-reference-existing-dimensions-and-define-parameters/35647/2 "2024-12-18T21:40:59Z")

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The Equal Constraint?

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**Author:** ![CerialPhreak](https://avatars.discourse-cdn.com/v4/letter/c/ce7236/32.png) [@CerialPhreak](https://discourse.shapr3d.com/u/CerialPhreak)\
**Post date:** [December 18, 2024, 10:01pm UTC](https://discourse.shapr3d.com/t/how-to-reference-existing-dimensions-and-define-parameters/35647/3 "2024-12-18T22:01:46Z")

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The equal constraint won’t let you create referential dimensions like in the scenarios I outlined in my original post.

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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:** [December 19, 2024, 12:56am UTC](https://discourse.shapr3d.com/t/how-to-reference-existing-dimensions-and-define-parameters/35647/4 "2024-12-19T00:56:56Z")

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Shapr3D has not implemented this yet.

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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:** [December 19, 2024, 1:10am UTC](https://discourse.shapr3d.com/t/how-to-reference-existing-dimensions-and-define-parameters/35647/5 "2024-12-19T01:10:17Z")

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The last time this was asked, they promised it by the end of this year. They’re probably not going to make it by then.

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**Author:** ![CerialPhreak](https://avatars.discourse-cdn.com/v4/letter/c/ce7236/32.png) [@CerialPhreak](https://discourse.shapr3d.com/u/CerialPhreak)\
**Post date:** [December 19, 2024, 2:42am UTC](https://discourse.shapr3d.com/t/how-to-reference-existing-dimensions-and-define-parameters/35647/6 "2024-12-19T02:42:33Z")

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Still got two weeks… Always a chance!